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GENP011278 Dioxins and Furans: Questions and Answers Todd Paddock Academy of Natural Sciences Nineteenth and the Parkway Philadelphia, PA 19103 Dioxins sod Fanns i ENP 011279 784090 tf 1989 Academy of Natural Sciences of Philadelphia ISBN: 0-910006-08-3 Library of Congress Catalog Caid Number 89-84471 Primed in tbe United S ues of America ii Dioxins and Furtos ! / 1 1 784091 _w GENPOmsn TABLE OF CONTENTS L ia of F ig u ra .................................................................... L ia of Tables..................................................................... . Acknowledgements.............................................................................................................. vi Executive Summary ..............................................................................................................vii Dioxins and Furans: Introduction and a Brief History ......................................................... t What is the history of dioxins and funits? .............................................................. 2 Discovering their toxic effects on humans and animals .............................. 2 Chick edema disease.................................................................................. 2 Concern about 2,4j-T and related herbicides.............................................. 3 Times Beach and other areas in Missouri ................................................... 4 Agent Orange............................................................................................. 7 The Seveso accident ................................................................................... 9 Conclusion................................................................................................. 10 Detecting Trace Amounts of Dioxins and Furans ............................ ...................... 11 Dioxins and Furans: What They Are, Where They Are Found, and How They Behave . . . Whai is dioxin7 .................................... Are all dioxins and furans dangerous?................................................................... Whai (actors affect the toxicity of dioxins and furans?.......................................... Where are dioxins and furans found?..................................................................... Are dioxins and furans found in and plants? ............................................ How long do dioxins and furans last tn the environment?..................................... To what degree do dioxins and furans spread when they are introduced into the environm ent?............................................................................................ Are dioxins and furans found in humans?................................................ .. How do dioxins and furans reach humans?........................................................... 13 13 IS 17 19 20 23 24 26 26 Sources of Dioxins and Furans ......................................... .............................................. 29 How are dioxins and furans created?..................................................................... 29 Whst products can be contaminated with dioxins andfurans?.................................. 30 P C B s........................................................................................................ 31 Heiachlorophcno ............................................................. 32 2,4,3-triclorophcnoxyacetic acid (2,4,5-71 ................................................. 32 2,4-dicbloropheooxyacedc acid (2A-D) ..................................................... 33 Chkaophenols .......................................................................................... 34 Polychlorinated benzenes.......................................................................... 36 Diphenyl ether herbicides.......................................................................... 37 Hexxchlorocydohexxpe ............................................................................ 37. Paper mills and products .......................................................................... 37 What products can produce dioxins and furans whenthey am boned?.................... 38 PCBs ....................................................................................................... 39 Polybroainated biphenyls (PBBs) and polybrorntnaerd diphenyl ethers (PBDFEs)..................................................................................... 39 Polychlorinated diphenyl ethers (PCDEa)................................................... 40 Chlorophenols .................................................................... 40 Tetnchloroethylene and polychlorinated benzenes..................................... 40 Polyvinyl chloride (P V Q .......................................................................... 41 Leaded gasoline......................................... 41 The burning of dioxins and furans............................................................ 42 Does the burning of paper, wood, peal, or coal producedioxins and fwans? . . . . . . 42 Dioxins and Furans iii 784092 G E N P 0 1 1281 t' ;TUTPrr Do municipal incineratora produce dioxins and furans?.......................................... 43 Do otter large combustion sources produce dioxins and finans?............................ 44 What about dioxins and furans from sewage plants, waste streams, and 1l landfills?................................................................................................... 45 Are there other processes that create dioxins and furans? ..................................... 45 I Conclusions on sources of dioxins and fu ran s....................................................... 46 The Health Effects of Dioxins aid Furans, in Animals aid Humans................................... 48 What are the health effects on anim als?................................................................. 48 i- Some general features.............................................................................. 48 Doses that produce no observable adverse health effects .......................... SO The shon-term health effects on anim als................................................... 51 Cancers.................................................................................. 52 i Reproductive effects ............................. 53 Mutagenic effects..................................................................................... 54 Immune effects.......................................................................................... 54 Effects on blood constituents..................................................................... 54 Are dioxins and furans hazardous to organisms in the environment?..................... 55 What are the pharmacokinetics of dioxins and furans? .......................................... 56 What are the effects of dioxins and furans on human health?................................. 59 The short-term health effects on hum ans................................................... GO The long-term health effects on humans ................................................... 60 C an cers...................................... 61 Abortions, birth defects ............................................................................ 62 Immune effects .......................................................................................... 63 Conclusions on health effects................................................................................. 63 How do dioxins and furans cause the health effects that they d o ? .......................... 64 Regulating Dioxins and Furans .......... 65 How do government agencies arrive at acceptable human exposure to dioxins and furans? ..........................................; .................................................. 65 t What has been done about dioxins and farm s?..................................................... 69 Conclusions and Recommendations ............. 72 Literature Cited ................................................................................................................. 74 A lis t of Documents Read but not G ird ................ ...................... ' ................................... 88 Appendix............................................................................................................................. 91 Recommended Reading ...................................................................................................... 92 Glossvy and List of Abbreviations...................................................................................... 93 i Index to A ntrim .......................................................... .................................................... . 94 Index to Subjects ............................................................................................................... 97. iv Dioxins and Furans t GENP 011282 784093 L ia of F leura Figure 1. Dibenzo-p-dioxin , ....................................................... Figure Z Dibeaxofuran ............................................................................. Figure 3. 2J.7.8-TCD D ..................................................................................................... Figure 4. Virtually a le lifetime daily dares of 2J.7.8-TCDD b an various agencies and countries ................................................................................................ 13 13 14 66 Lbl of T abla Table l. Relative toxicity of dioxins and furans .................................. Table 2. Products that can be contaminated with dioxins and/or furans.............................. Table 3. Chlorinated products that can produce dioxins and/or furans when burned............ Table 4. Acutely lethal single doses of 2 J .7.8-TCDP (LD50)............................. Table 5. Lethal exposures to 2J.7.8-TCDD in water (LCSO).............................................. Table 6. Lowest dose with an observed adverse effect (LOAEL)....................................... Table 7. Lowest concentration with observed advene effect (LOAEL) .............................. Table 8. Highest concentration with no observed advene effect (NOAEL)......................... 15 30 39 49 49 50 51 51 Dioxins and Furans 784094 GENP 011283 4 0 Actaowtedacmenti I wish to extend ray sincere gratitude to those people who reviewed lections of this report: Dr. Keo Burgess of Dow Chemical Cdmpny, Dr. David Firestone of the USFDA, Dr. Annette Guiseppi>Etie of Drcxcl University, Dr. Rolf Hartnng of the U nnosity of Michigan, Dr. Paul Michael of Monsanto Company, Dr. Tom Robinson of Vulcan Chemicals, Dr. Steven Safe of Texas A & M University, Dr. Fred Tschiriey, Professor Emeritus of Michtgn State University, and Mr. John Wilkinson of Vulcan rhwnicah. Their eontmeaM greatly unproved the report. I also wish to thank Dr. Robert Ranghmwi of Harvard University, Dr. P.E. des Rosters of the USEPA, and Dr, Alan Poland of the University of Wisconsin for their many explanations, ideas, aid advice. These people and many others took time from their busy schedules to answer my numerous questions. I especially wish to thank Dr, Ruth Patrick and the Environmental Associates at the Academy of Natural Sciences in Philadelphia, far providing me with the resources and freedom to write this report, I greatly appreciate the opportunity they gave me, and the constructive criticism that 1 received from than. vi Dioxins and Furors GENP011284 i i It 784095 & ft Executive Summary In the dioxin is infamous because it was the substance in Agait Orange blamed for a host of diseases in Vietnam veterans, and the substance that contaminated Tunes Beach, Missouri, prompting the federal government to purchase the entire town. Since then, the discovery of rfinira in inrincraipr emissions has caused further concern. There are actually many kinds of dioxins. The chlorinated dioxins have caused the most concern. A related family of compounds called chlorinated fuxans are very similar to dioxins in their distribution, toxicity, and behavior, although not as much is known about them. The -iiinmiamrf dioxins and furans are the subject of this report. One particular dioxin has received more attention than any other, because it was found in relatively large amounts in some widely used chemical products, and appears to be the most toxic. This dioxin is 2J.7.8-TCDD. The word dioxin is commonly used to mean 2J,7,& TCDD. A great deal more research has been done on 2J.7.8-TCDD than on the other dioxins and furans, and this report is based largely on studies of 2J,7$*TCDD. How toxic are hIm im ami furans? Based on laboratory and field studies; 20 or so of the 210 chlorinated dioxins and furans are considered to be extremely toxic to animals. They accumulate in the tissues of organisms, and are often the only types found in organisms ham the wild. Most dioxins and funm appear to be almost nontoxic, and do not accumulate. What factors affect the toxicity of dioxins and furans? The toxic effect of a dioxin or furan on an animal depends on more than the type of dioxin or furan. U also depends on the species of animal, the status of the animal, the route of expanse, and the substance in which the dioxin or furan is present Some animal species are thoMMda of times more sensitive than others to the toxic effects of the sune dioxin or furan. How do HimrfM ukJ (brans reach haraaas? The major routes of p u w are generally conridaed to be eating contaminated food nd breathing entitaminated panicle. Panicles in air, especially near ixbao treas or Urge sources of combustion products, can be with dioxins and furans. Trace levels of Dioxins and Furans vii 784096 B * P 0U28S <4 *r dioxins and furans haw been found in a variety of foods in Japan. Canada, and Europe, and the same is probably one of foods in the U.S. Dioxins have also been fotmd in fish from cenain areas in the ILS. Are dioxins and forans found in humana? Dioxins and fmans have been found in samples of blood and fatty tisme firm posons in numerous countriesj including the U.S., Panada, Japan, Vietnam, and several countries in Europe. Based on these findings, it is generally agreed that the population at large in many parts of the world has been exposed to low levels of dioxins and furans. What are the health effects of dioxins and forans? The long-term health effects of these compounds have been intensely investigated, and they are now among the most-studied substances with respect to their effect an animal and human health. Dioxins and furans cause morality and/or cancer in many animal, but thae is no conclusive evidence that they cause cancer or any other life-threatening health problem in humans. No documented human death has occurred because of an exposure to dioxins or furans: People have been exposed to relatively large amounts of dioxins and furans (1 microgram or mote) during industrial accidents, and other incidents of accidental contamination. The health effects were serious, but subsided with time. With the exception of severe acne, most researchers have found no serious, long-term health problems with exposure to dioxins, even at the highest reported levels, and after ten to thirty y e n have elapsed. Haw a n dioxins and ftuana created? Dioxins and furans have no useful purpose and have never been manufactured deliberately, except in small amounts for research purposes. They are known to be created in two major ways (1) they are created by unwanted side ret i ons, which take place during the ytwmirj i pmfMWf used to manufacture useful p*** met is biocides, paper, Hixjufawwm, and preservatives; (2) they are crested when a sabsance containing chlorine is burned. <* when a substance is boned in the presence of chlorine. viii Dioxins and Furans GENP 011286 784097 Dioxins and/or furans have been found as contaminants in the following manufxtured products: Product PCB hexachlorophcno 2.4.5-T 2,4-D chlorophenols with 3 or more chlorines polychlorinated1benzenes diphenyl ether herbicides hexachlorocydohexane paper products * I could find no analyses of these products for funits. Containinants Fumns Dioxins* Dioxins* Dioxins* Dioxins and Furans Other produca derived from chlorophenols have been identified as possibly contaminated and are under investigation by the U.S. Environmental Protection Agency l (USEPA) and others. What products can produce dioxins mad Atrans w tm they arc bunted? The following chlorinated produca or substance* can produce dioxins and/or furans when burned: Product C oetstnlnana PCBs ' polybrominaud biphenyls (PBBs) polybrominated diphenyl ethera (PBDEs) polychlorinated diphenyl ethos (PCDEs) chlorophenols j tetrachloroethylene polychlorinated boizcnes polyvinyl chloride (PVC) frffart^d paper, wood, peat, and oral dioxins and furans Furans Dioxins and Furans "* ** "* "` *" `` "" Note When a material is burned in the laboratory to determine whether it is capable of producing dioxins and furans. it is typically burned under those conditions most likely to produce dioxins and furans, or that produce the largest quantity of dioxins and furans. Therefore, the sene substance may produce much smaller amounts of dioxins and furans under the uncontrolled conditions of a fire, or in the highly controlled conditions of an incinerator,. Dioxins and Furans ix 784098 (S ' o Incinerators and other largo combustion sources, sewtgc plants, waste streams, and landfills are also sources of dioxins and funns. There are many sources of dioxins and furens. The combustion sources are widespread i and numerous. Highly manriacturing and waste sites are fewer in number and usually local prabtems. The relative importance of the two major sources of dioxins and furens (chlorephenols vs. combustion) is not yet known. It is generally agreed that modem industrial activity, not the burning of wood, is the primary source of dioxins and furans to the environment. Where are dioxins and furans found? Dioxins and furans are present at trace levels in many places; and at relatively high levels at a small number of contaminated sites. The presence of dioxins and furans is usually associated with the production, storage, use, or disposal of cfalorophenol-bxsed compounds. Id addition, they have been deteded at low levels in urban areas, where they are believed to be the product of numerous combustion processes. As our ability to detea dioxins and furans improves, it is likely that they will -be found in more places. Dioxins and furans have been found in organisms from contaminated areas, and from fish in marry areas of the U.S. Plants typically contain these compounds as levels much below the surrounding environment, and only when drey are grown in highly contaminated soil. Fruits dO not CO atfV w gh ftXJC CTOpi m ay vw iifw ^ m raai'n th a n . How long do rikrriM sad A rm s last fn the esrironmeat? 23.7(&>TCDD car be broken down in a msner of days in the environment, if it is mixed with the proper organic solvent and etporod to uimviofei light On the surface of the soil, without a solvent 23,7JS-TCDD baa an environmental hilMiAt of one y e or less, due to slow photodegredation and evaporation. Undergrou nd and in redimetts, this very stable compound degrades much more slowly, with a half-life of shore 10 yean. Very little is known shore tbs half-lives of other dioxina and firm s. In general, diaxina and furens with fewer dan Aw chlorines ire broka down more quickly that 2^,7,8-TCDD. The dioxin or A nn with eight chlorines is mare resistant to breakdown. x Dioxins and R ians L j ENP 011288 I 784099 %d (9 i To w ha degree do dlondM a id fa m e spread when they a rt introduced Into tbe T lrw ttiT Dioxinsand fuims bind voy strongly to the aqatric carton present in panicles of soil, in writments, apd to the particles found in thg air. These policies can be lifted and earned by w ad or moving' water. Dioxins and funna cm be tnnsponed great distances in air, and smaller I distmees in water. In soil and sediments, dioxins sod farms appear to mignte very little or not at alL Areas of severe contamination have typically ronained local problems, and most are not I expected to spread the contamination to nearby areas. What has beeaidooe about dlmtlna and fttrani? Became they are very potent toxins and carcinogens in labancory animals, tegulauxy agenda from various countries have sued guidelines for human exposure to dioxins and farms. These guidelines vary by more than a thousandfold, due to different interpretations of the same animal laboratory studio. Aa dioxins and farms have been as contaminants in products, the mmnfacturen have lowered the levels of contamination. The USEPA h a cancelled or restricted the manufacture, use, and ditpnoi of msixy of the products containing hazardous levels of dioxins and fanns, and the disposal of wastes Croat the manufacture of many products. Many contaminated sites have been cleaned up, and many more ate on the Superfund list. Conclusions and Recommendations Baaed an the many studies already published, dioxins and farms do not appear to be a hazard to o a health when we are e tpoaod to the low levda typically preaent in the environment. Several groups of people need special attention became they may be exposed e greater thm nonnal amounts of dioxins and farms. These indude bran-fed babies (because dioxins and farina are usually present in tre a t milk), end w aken in industries that use contentmated product! We shookl continue to mariior the health of groups of people who were exposed a Inge amounts of these compotnufa, a who were expored to smaller mtnmci far a long time. This will enable;Ius to identify any longhorn health effects not already ircogiircd. Now that Dioxins and Funna xi i 784100 GENP 011289 % ei J we have the ability to determine the extent of jn individual's past exposure to dioxins and furans through a blood test, the identification of exposed person is modi easier and m an accurate, making such studies more powerful We also need to determine how dioxins and furans cause the effects that they do, and i why their toxicity varies so greatly between species. Such an undemanding would not only have preventive or therepetaic value, but is also critical for accurate assessments of the risks these compounds pose to humans and other organisms. Because of their demonstrated toxicity to laboratory animals, plus their distribution and persistence, some dioxins and furans ate a potential hazard to organisms in the environment. There is a great need for more study in this area. We need to know what are unacceptably harmful levels far the various organisms in the environment, and the nature and amount of dioxins and furans from the various sources. Whai appears to be the largest amount of toxic dioxins and furans is buried in landfills or stored at p e t or pesent sites of manufacture or use. We need to develop safe, yet practical ways to contain, or better yet destroy, this contaminated waste. We may need to reduce the amounts of tnd furans occurring as unwanted contaminants of some products, Great reductions have been made in certain products in the past, and further reduction may be necessary. Unfortunately, such reduction can result in very highly oouaminxed waste streams, and poper disposal is difficult and expensive. Therefore, the emphasis needs to be on preventing their crearion dining the manufacturing process: We also need to reduce the unwanted creation of dioxins and furans (hiring combustion. For maniple, iocm axm can be operated under an d mens that reduce the errarion of dioxina and flim n. More than one billion dollars has been spent in the U.S. alone far the reserech of dioxins and f u m , and this research has greraly expanded oar knowledge. With this knowledge, and with improved tndmnlngig for both reducing fours sources of there compomda and cleaning up presently contaminated areas, and furans should be regreded s i a manageable poblem. xii Dioxins and Furana GENP 011290 784101 *> i i Dtoxin* tod Farms: Introduction and a Brirf Hhtny When moa people use the term dioxin. they mesa a single cnmpn^pid, often I refened to u "the a n a toxic substsnee ever made by man". In the U.S., dioxin is infamoq* because it was the substance in Agait Orange blamed for a host of <h w in Vietnam veaeran* and the| substance that contaminated Timex Beach. Missouri, prompting the Federal Government to purchase the entire town. Howevo; the dioxins (short far chlorinated dibenzo-p* dioxins) a n a large family of compounds whose toxicity varies or, for many types, is unknown. A clooely related and very similar group is the furans (chlorinated dibenzofarms). Dioxins and furans have been discovered in unexpected places. They are in fish from lakes and rivers; in common paper products, in auto exhaust, and in the ash from municipal and industrial inemereiot* Dioxins and Anna will continue to be found in new place*. In part, this is because they can be measured in extremely small amounts, and have been looked far in many place* Also; many rtimiM and A nus are very stable, can remain in the environment for yema, and can accumulate m organism*. One particular dioxin has received more attendnn than any other, because it was found in relatively lageianiounu in some widely used chemical products, and appears to be the most toxic'. This dioxin is 2J.73*tenachkxodibeszo-p-dioxin, also known as 2J,7$-TCDD, or simply TCDD, The word dioxin is commonly ured to m e 2J.73-TCDD. Much of the general public's knowledge of dioxins a d A nns was pined as a result of i a few widelyptrticTiod indden a or conuumaic* A brief history of dioxins and Ann* with stannaries of a few of the matt publicized inoriott* can sene to remind us of how there compomda became so well hew n. i 1 Here a d in the rea of the report, toxic" m ens that the substance is isxoriafert with advene health effect* but not necessarily effects tint are seriau* or permanent. i Dioxins a d Roans 1 L i I 784102 I G N P 011291 ^0 < What b the history at fa* and furmns? IK Dioxins and fames were synthesized by organic chemists in the 1930s and ere patented in 1939 as constituents in a product used for electric insulation (cited in Huff and Wassons, 1973). Different dimiiM and funns were tested and in some cases patented as agents against bacteria, insects, and fungi, as intermediates in chemical processes, and as flame retardants, from the 1930s to at least 1970 (cited in Huff and Wassom, 1973). Discovering their toxic effects on humans and animals I The toxic effects of dioxins and fuians in humans were more or less unrecognized until 1937, when Dr. Karl Schultz, a dermatologist at the University of Hamburg in West Germany, i tried to determine why workers at a nearby chemical plant were developing a severe form of acne, called chloradie (Gough, 1986: pp 29-33). After some careful tests. Schultz concluded that a contaminant in one of the plant's products (2,43-triehIarophenoI) was responsible for the chloracne, and identified the contaminant as 23,7,8-TCDD. We now know that 2,4,5* tricblorophenol is always contaminated with 2J,7$-7CDD, and therefore trace levels of 23,7.8TCDD are also present in the products made from 2,43-trichloropbenol. Schultz and colleagues published several papers in 1957, showing that several dioxins i and fuians induced acne when applied to rabbit ears (the standard and most sensitive test at that time), and that small doses of 23.7,8-TCDD caused liver damage and death in rabbits. The plane chemists found a way to reduce the amount of the contaminants famed doing the production of their 2,43-trichlarophenal, and the chloracne problem in their workers aided. Chick edema disease Abo in 1957, scientists in the U 3. Food and Drag Admirasaitton (USFDA) were trying to detainine the au se of m outbreak of millions of deaths of chickens in the U 3. (Firestone. 1973). They determined in 1958 that the cause of the disease (chick edema) was toxic canotnmaas in commercial fatty adds that woe part of the <*>** feed. Symptoms included excessive fluid in the heat sac and h^nmimi cavity, and liver damage. Although the cootamtnam was not yet identified, the USFDA issued a regulation m 1960 that required fatty I 2 Dioxins and Fuians i| it l QEtfP 0 1 784103 acids to be proven free of the contaminants through a 3-week chick-feeding bioassay. Advenes in detection techniques made it possible to further identify the cantaainanta. and in 1966 it was dcmminrd that lA 3t735-hexachlonxlibenzo-iHlkaui was one of the that a synthetic hrrachiorodibenzo-p-dioiio produced the disease in (Firestone, 1973). It had been shown as early as 1936 (cited in Huff and Wasson, 1973) that dioxins could be produced by heating chlorophenols. and the USFDA scientists proposed that chlorophenols woe the source of the dioxins in the toxic fats being fed to chickens. Chlorophenols, including trichlorophenoi and pentacfalorophenol, were widely used as agents against slimes, bacteria, termites, and as herbicides. The USFDA scientists were able to produce a variety of dioxins by heating various commercial chlorophenols, and found then same dioxins in the toxic fit. They tested these dioxins on chickens, found that they produced chick rriemx, and found that the mast toxic dioxin was 2J.7.8-7CDD. Finally, it was determined in 1972 that the source of chick edema disease was fat derived from hides (from cattle, hogs, sheep, and other animals) that had been tim ed with commercial pemachlorophenol (Metcalfe, 1972, cited in Firestone, 1973). Concern abort 2.4.5-T and related herbicides In 1970, at hearings before the U.S. Congress, evidence was presented to show (hat the widely*used herbicide 2,4,5-criehIaropbetioxyacetic acid (2,4,5-T) was capable of causing birth defects m rats and mice (cited in Huff and Was*, 1973). During that same year, a study showing similar results was published (Courtney ct aL, 1970). It wax proposed that the rctativefy high levels (approximately 30 puts per millioo [ppm]) of 2J.73-TCDD contamination in 2A.5-T m e probably responsible far the binh defects (cleft palate, cystic kydney) in mice and ran, and a study an 2J.73-TCDD found that it affected reproduction in rats (Spanchu et aL, 1970). Based an these Findings and the earlier findings of the toxicity of 2J.73-TCDD to bureaus rod *"", the U.S. D e triment of Agriculture (USDA) decided in 1970 to cancel registrations for the use of 2,4,5-T in certain areas; for example its use on human food crops, near bodies of water, rod around homes (Gough. 198& p 138), They did not cancel registration Dioxins and Fuxans 3 L 784104 Tor other uses of 2,4,5-T if the levels of 2J.7.8-TCDD were below 1 ppm (cited in Huff and Wesson, 1973). However, the USDA and (J.S. Department of Health, Education, and Welfare issued i joint statement that 2.4,5-T and 2J.7.8-TCDD may cause birth defects in mice and rats (cited in Huff and Wasson, 1973). Also in 1970, the US. Department of Defense stopped using the herbicide Agent Orange in Vietnam. Agent Orange was a half-and-half mixture of 2.4.5- T and 2,4-dichloropheaoxyacedc add (2,4-D), and was contaminated with Z3.73-TCDD. In 1971, a Science Advisory Council from the U.S. National Academy of Sciences recommended to the US. Environmental Protection Agency (USEPA) that the registration of 2.4.5- T be restored for use on forests, rangeland, and rice Gelds, with certain restrictions on its use (Gough, 1986: p 138). For example, they required that present stocks of 2,4,5-T have less than 0.5 ppm 2J.7.8-TCDD and that newly manufactured 2,4,5-T have' less than 0.1 ppm (cited in Huff and Wassom, 1973). In 1973, the Science Advisory Council recommended that no more than 0.1 ppm 2,4,5-T be allowed in water or on edible food products, if they were for human consumption (cited in Huff and Wassom, 1973). In 1979, (he USEPA issued an emergency suspension of most remaining uses of 2,4,5- T, based on accumulating evidence that 2J.7J8-TCDD caused cancer and birth defects in laboratory animals, and because of a 1979 study that showed elevated levels of spontaneous abortions among women near Alsea, Oregon, where 2,4,5-T was sprayed (Gough, 1986: p 138- 145). A pratel of scientist! subsequently reviewed this 1979 study and concluded thst because of a flawed design, the study was incaprtte of showing either the presence or absence of effects of expostm to 2/4.J-T (Coulaon and OIsjos, 1980, died in USEPA, 1985: p 9*25). From 1979 until 1984,2,4,5-T was used an rice and sugarcane fields, pending settlement of a suit between the USEPA tmd manufacturers of 2,4,5-T. AH companies withdrew flora the suit by 1984, and the USEPA then cancelled all uses of 2,4,5-T wd the closely related hertridde SUvex. Times Beach and other areasJn Mioomi (Much of the following dtemrion is hoed ao a dnpter in Gough, 1986) Hraschlorophene, a germicidal product used as a skin in hospitals, in germicidal soqo, and in some veterinary products, is produced flora 2,4,5-trichlorapbenol, the 4 Dioxins and Ftaans *9 % same chemical used to manufacture 2,4,5-T and related herbicides. When manufacturers of 2,4,S*<richlaropfaeaol*bRied products became aware of the toxic properties of 2J.73-TCDD, they found ways to (really lower the conccnnxoooa in their Gnal products. However, this purification process caa a n te wastes with very high concentrations of 23,73-TCDD. If this waste is not disposed cf properly, it can be a bazarl to humans and other organisms. Improper disposal of such wastes was the cause of the contamination of Times Beach, Missouri. A chemical plant in Verona, Missouri, produced hexachloropbene from 1970 to 1972; The purification of their product (by distillation) resulted in a thick, oily, 2,3,7,8-TCDD* contaminated waste called still bottoms. The plant's still bottoms were hauled away by a separate company, sod sold in turn to a waste oil buyer. The waste oil buyer then used the still bottoms in a secondary business, in which he sprayed oil to keep dust down in horse arenas, private ro d s, and parking lots. Hanes, birds, and other animals became sick and died following the spaying of one of the bane arenas in 1971, and a child who played in the hone arena was hospitalreed with bladder inflammation and bleeding. The U.S. Centers for Disease Control (CDC) began an investigation of the poisoning episode at that sable in August, 1971, three months after the spraying. They and local doctors die episode as chemically related, but could not identify the disease or the contaminant. In the meantime, the owners of the first hone arena and another arena had suspected the cause of the illness was the sprayed oil, and had removed the top layer of soil from their arenaa and placed it in a nearby landfill. The CDC investigation continued, and in 1973 they had identified 2J.7.8-TCDD in swnplea of dirt from the arenas. They notified ibo Missouri Deptm e n i of Health in 1974, and the CDC and state began a joint investigation of the episode. The origins of the waste ail were quickly determined by the investigators, but identifying the many aeaa that had been sprayed with the oil was more difficult Fortunately, the owners of the first m u had remedy followed and kept'records of the spraying done by the waste oil buyer, and then records were used to locate other contaminated areas. Arenas and trailer peiks had been cnrraminucd by spraying, rod soil from the arenas was removed and Dioxins and Funns 5 784106 g ENP011295 placed in landfills, oa fanns, id used ss fill for building projects. Aim, the waste oil buyer had spreyed 23 miles of unpaired streets in the town of Times Beach, Missouri, from 1972 to 1976. The contaminarion of Times Beach was not confirmed by the federal government until December 1982, when their soil tests showed 5-300 pans per billion (ppb) 23,73-TCDD in the soil from the streets of Times Beach. Based on ihe results, the CDC recommended that the town of Times Beach was unsafe for its inhabitants, and in February 1983 the federal government announced it would buy the homes, properties, and businesses of Times Beach. The many other contaminated sites in Missouri (51 in all, according to USEPA, 1987a: pp 2 J2.35) are being dealt with in various ways. The USEPA and CDC have removed mi), decontaminated the soil, restricted access, and advised minimal contact with soil, depending on the level of contamination and possibility of exposure (USEPA, 1987a: pp 2.18*19). Based on studies of residents of the most highly contaminated areas in Missouri, it appears that the people exposed to 23,7,8-TCDD have suffered few if any long-term effects, although several commonly used areas were contaminated with extremely high levels of 2J.7.8TCDD (as much as 31 ppm in the soil of one horse arena). The people who were exposed to high levels of 2J.73-TCDD in the arena soil suffered from a variety of effects, including nausea, headaches, diinhea, nosebleeds, chloracne, and severe bladder inflammation. Their health subsequently reamied to normal (reviewed in Reggiam, 1980}. A smdy of the readenti of a trailer park that had 39-1100 ppb of 2J,7JB*TCDD in the sail (b ad abnormal levels of some blood aaraituctaa. th* suggeoed long-term effects oa the liver and immune system (Stesr-Grees et aL, 1987). However, no liver changes could be directly delected, and no excess of illness was reported. The authors noted. T h e effects we obrened may be merely, pmt of the normal, adaptive p w * to a toxicologic challenge, and well within the normal reserve capacity of the affected argre systems (Le., they are m arten of eipow re and not sig n of diseaae).* 6 Dioxins sod Furens I 784107 ' & Agent Orange Herbicides wen used by the U.S. in the Vletmm War from 1962 to 1970. Agent Orange, a half-and-half mixture of the herbicides 2,4,5-T and 2/f-D, was sprayed ova- South Vietnam from 1963 to 1970, accounting for more than half of all beriaddes mw-h ihae. SaHW mixtures w en called Agaits Purple, Pink, and Green. Baaed on analyses of Agent Orange manufactured before 1970, the mixture sprayed an South Vietnam was contaminated with from 0.02*34 ppm 2J.7.8-TCDD (Esposito et al, 1980: p 98). The U.S. Air Force (USAF) egimaies that Agent Orange had a mean concentration of 2 ppm 2^,7,8-TCDD, Agent Purple had a mean concentration of 33 ppm, and Agents Pink and Green were estimated to have 66 ppm (Albonese, 1988: p 3). The large-scale use of herbicides in Vietnam ended in 1970 became of concern about the effects on the environment and inhabitants of South Vietnam. However, that concern has been almost entirely eclipsed by concern about tbe possible effects on the health of soldiers from the U.S. and other countries who were exposed to large amounts of tbe herbicides. Because of this concern, several large studies by the CDC and USAF have been conducted or are tmderway. The USAF study investigated the general health and rates of cancer and death among Vietnam veterans who were exposed to herbicides, as well as birth defects among children of the vom its. The CDC study investigated the health of Vietnam veterans in genenl, moo of whom woe not exposed to Agent orange, and thoefore is not relevant to this rfimmiion. The USAF Health Study is investigating tbe health of USAF penonnd who participated in the aerial spraying of herbicides over Vietnam. The spraying program was called Operation Ranch Hard; Ranch Hands include the men who flew the planes, and all men who worked with the herbicide and spay equipment used far the aerial spraying. The health of Ranch Hands is being compxed to a carefully matched group of USAF penonnd who flew in and out of Southeast Asia (bo not Vietnam) during the same period. The mast recem report from this study focused on eleven health effects that studies of "m i end humani have associated with expastae to 2J.7.8-TCDD (AHunese, 1988). They reported that for 6 of the 11 effects. Dioxins and Funna 7 L 784108 GENP 011297  . differences wen detected between the two groups, and for 5 of the effects the difference was in the direction that would be expected from current knowledge of the effects of 2^,73-TCDD. The six effects were increases in the rate of cancer, increases in the a m ber of birth reported in children of the veterans, an increase of psychological changes, an increase of liver changes, ao increase of cardiovascular changes, and an inaease in changes in the endocrine system. However, no differences were detected in the sperm count or proportion of normal sperm, the rate of heart disease and heart attack, the immune system, overall mortality, and other health effects that studies of animals and humans have associated with exposure to 2J.73-TCDD. Follow up studies, including an investigation of the birth certificates and health records of all children of the veterans, are now under way. Albanese (1988) concluded that while "At this time one cannot ascribe the observed group differences to an effect of dioxin", the study also "does not exonerate dioxin as a causative agent of these differences." He noted that the study did not find that the health effects increased in severity with a greater exposure to Agent Orange, and that some of the characteristic effects of exposure to 2J.7.8-TCDD were not observed. He also noted dm five of the six group diffoences were in the direction of 2,3,73-TCDD effects; and that the calculation of exposure was only an estimate. Finally, he noted that the sample sizes used in the study made it possible to detect common diseases and death, but almost impassible to detect rare diseases. An importMU pan of the controversy over the passible health effects of Agent Orange is the question of detennmieg expanse: what veterens were exposed and what was the level of expen se? Recent stadia indicate that 2J.7.8-TCDD persists far decades in the fatty tissues of humans (Schemer and Ryan, 1988), and levels of 2J.73-TCDD in tbs blood can be conelated with levels in the fairy tin a a (ftttenoo a aL. 1988). Measurements of 2J.7.8-TCDD in the blood can therefore be used to determine a penoo'i level of exposure id 2JJ3-TCD D , even if the exposure occurred many years before. The CDC recently reported the levels of 2J.73-TCDD in the blood of approximately 700 veterens who were part of the Vietnam Expoieoce Study or the Ranch Hind Study. Ranch 8 Dioxins and Forms GEbfp 11298 784109 If ft Kind veterans had significantly higher levels of 23,73-TCDD in their blood (mesa of 49 p per crillka (pptD dun did other Vietnam* Air Force veteran (mesa of 5 ppt). Seventy-nine percent of Ranch Hands had blood levels above 10 ppc, and many had levels of 100-300 ppc (CDC, 1983). However, other Vietnam veterans did not have higher levels of 2J.73-TCDD in their blood (mean of 4.8 ppt) than did non-Vietnam veterans (tneaa of 4.9 ppt) (CDC, 1987). It appears that Ranch Hands, but not other Vietnam veterans, were exposed to significant amounts of Agent Orange. To detomine past exposure, the CDC used an estimated half-Ufe1 of about seven yean (CDC, 1988), and tberefrae assumed that two to four half-lives have passed since Vietnam veteran were exposed to 2J.7.S-TCDD in Agent Orange. Recent work by Kissel and Robrage (1988) suggests that the half-life of 2J.7.8-TCDD is inversely related to the concentration of 2,7*7CDD in the body, and that the half-life is significantly shorter when concentrations me relatively high (e. immediately after exposure). If so, the CDC may be underestimating Vietnam veterans' pan exposure to 13.7,8-TCDD in Agent Orange: The Seveso accident In 1976, a cloud of 2,4,5-trichlorophenol and caustic lime, contaminated with 2J.7JJ* TCDD, was released over the town of Seveso, Italy and nearby towns, when a chemical plant's reactor vessel went out of oonooL Approximately 700 acres inhibited by 38JOOO people were comamimned with 2J.73-TCDD (Mamoiacovo et aL, 1983). The level of 23,73-TCDD ranged firm greater than 150 ppt in the soil of tbo mora comantnared area to less than 50 ppt to the soil of the least conramnraed area (WJpf and Schmid, 1983). Vegetation (indoding gradea vegetables raal archrad finita) was contammaied with from more tiran 1000 ppb 23,7,8TCDD to less than 1 ppb, which was the limit of detection ra tint time (Wfpf and Schmid, 1983). The accident resulted in the deaths of about 3000 domestic animals (almost all rabbits and chickens); some of these animals died almost immediately aft the accident, and their * The half-life is the amount of time during which the 23,73-TCDD present in the body is reduced by one-half, Dknmi and Fttnns 9 L 784110 GENP 011299 6 & w tjiyjtM woe attributed not to 2J.7.8-TCDD, but to the other chemicals in the cloud or to deliberate slaughter. (All animals given a lethal dose of 2J.7.8-TCDD take at least two to three weeks to die alter their exposure.) One hundred and eighty-three people, mostly children, were confirmed as having contracted chloracne, indicating that they were exposed to significant amounts of 2J,7,8*TCDD. It was presumed that children were exposed to greater amounts because they played in the vegetation, and may also be more sensitive. All cases of chloracne cleared up within 5 years, although the 15 most severe cases resulted in permanent scars. Aside from chloracne, no other health effects were confirmed by an investigation of the accident (Wipf and Schmid, 1983). However, there was concent that the effects of the exposure might include birth defects. The Italian health authorities advised the inhabitants of the area to avoid becoming pregnant, and many women requested abortions after the accident. A panel set up by the Italian government investigated, from the beginning of 1977 to the end of 1984, all suspected birth defects in children born to. women who were inhabitants of the area at the time of contamination (Mastroiacovo et aL, 1988). This study did not find an increased rate of birth defects in children bom to the exposed women. The authors noted that rare defects could not have been detected bemuse of the small number of births, and that it was possible that sporumcous abortions decreased the number of children bom with defect! They cited one study that found an increase in spontaneous abanions after the accident (Sand et aL, 1983), and ooe study that did not (Bianco et aL, 1986). Conclusion The conamrmtioo of Times Beach and Seveso, and the health effects attributed to use of the hertneide 2,4,5-T, especially from Agent Orange, have made dioxin a household word with in infamous connotation. Much sttmaon has been pud to the potential danger of dioxins tod A nns and their wide presence in very snail qumtides. Yet investigators of the health of the people expoeed to relatively large qnsniriea have found little evidence to justify the enormous m a u n to these incident! Nevenbefca, dioxins and furans are present in our environment, in organism! and in u ! and o n be extremely toxic, at least to other organism! A great deal of money and other resources have been spent on the research of dioxins and 10 Dioxins and Fttrans GENP 011300 784111 furans, and will continue to be spa*. The question then it, what do we kanr about furans? "H and Detecting Trace A aoaata of Dtoxica aad Form s One of the difficulties of discussing dioxins and furans it the almost unimaginably mail quantities we can detect with modem techniques: as little at one triHicnth. or in some cases even a few quadriHiomhs of a grant. Hie following examples illustrate how little these quantities ate; If we assume a drop of w its' to be equal to 0.05 milUktea (20 drops to a milliliter), then one ppb is equivalent to one drop of water in 13.200 gallons, or a pool 20-feet square and approximately 4.5-fcet deep. One ppt is equivalent to one drop of water in 13,200,000 (thirteen million two hundred thousand) gallons, or a pool of water as long and wide as a football field, and approximately 28-feet deep. Ooe pan per quadrillion (ppq) is equivalent to one drop of water in 13.200,000,000 (thirteen billion, two hundred millioo) gallons, or a 6square-mile lake, approximately 10.5-feet deep. Dioxins and furaiu were among the very first compounds chemisa could measure in one billionth of a gram (in 1970) and ooe Billionth of a gram fin 1976), and they are now apptoarhing the detection of one quwfcillkxufa of a gram. As the new techniques for detection were developed, dioxins and furans were used to rest the techniques beosne they appeared to be toxic at extremely low levels. Before the detection techniques were developed, rcscacben used animsls such as y an g chickens to test the toxicity of dioxins and A nns (per* comm, David Fueamoe, USFDA). Dioxins lend themselves to the technique used detect snum ts this small. They react with very few other chemicals, many last a long time, and they dissolve readily in organic solvents. Also, dioxins red finns are relatively simple molecule* The molecules of many other toxins are very complex (pa* comm, David Firestone, USFDA). In order id detea imounti this small, it is first necessary to isolate the substance you want tomeasure from all the other snhsancei that are present in a typical sample. This process Dioxins and Furans 11 784112 gejsip is gait* analytical clean-up; the chemist puts the sample through a complicated and delicate preparation process, involving extractions, washings, and separations. Ooce the ample has been cleaned up, the separated need to be detected and their amounts measured. This can be done ming several techniques, including an Elecaon Captive Detector, Flame lonirarian Detector, or Mass Spectrometer, along with a Gas Chromatograph (pen. comm., Annette Guiseppi-Elie, Dreael University). In addition to the difficulty of detecting these very small amounts, the unicity of these compounds necessitates great care in their handling. Therefore, detecting the presence of dioxins and furans at levels approaching 1 ppt is a very time-consuming, expensive, and difficult undertaking. An experienced analytical chemist needs several months in Oder to prepare the laboratory for detecting a panicular chemical at these extremely low concentrations. Once everything is in place, the analysis of just one sample costs about $2000 in mmm'iH. requires the attention of an experienced analytical chemist, and typically consumes a half-day of work (pets, comm., Robert Baughman, Harvard University). A much cheaper and quicker method has been developed for determining the level of toxicity of a mixture of dioxins and furans in a am ple. It has been established that dioxins and furans induce a specific enzyme and bind to a specific protein in miwmIi and humans (Poland et al, 1979). Rather than using analytical chemistry to determine the amounts of various toxic congeners* of dioxins and furans in a sample, cell cultures sre exposed to the sample and the above biochemical responses are measured. The accuracy of these methods have been verified by comparing their results with the results of chronic toxicity tests using laboratory animals (Sale, 1987; Sawyer et al. 1983). 1A congener is a single, particular dioxin or finan, e.g. 2J.7.8-TCDD. 12 Dioxins and Furans GENPO11302 L 784113 P te rin in d Farm ; W hat They Are. W lic i T lw Aw Fotiad. u d Haw T h ^ bum What is dteria? th e dibenzo-para-diaxia structure (see Figure 1), which provides the framework for tens of thousands of compoinidi, is nude up of two benzene rinp joined by two oxygen atoms (hence dibeaxo dioxin). th e "per' means the benzene rin p am attached to opposite sides of the dioxin molecule, md it is usually as simply 'p*. Benzene is a ring of six carbon atoms (one at. each comer) and six hydrogen atoms (one bonded to the carbon atom at each 91 91 Figure I. Dibcrao-p-dioxin Figure 2. Dibenzofman In wMttwi to riihgmvjuHwiin, then is the related structure <*11**a dibenzofunn (see Figure.2). A dibenzorinn, like a dtonp-p-rttexia. is compoaed of two benzene rings. However, the benzene rin p are joined by ana oxygen amra, iaaead of two. th e smglo oxygen dut j tbs two im p forms the fu ra p in of the molecule. A farm is a ring like hwMwia, bus is wwto tg) of four cartoon areas plus one other atom (in this cue, that other atom is die oxygen aura). Both dtarint and fu n u hare eight camera ( fa r an each benzene ring), free to react with other stoma. Them other stoma can be, for example, hydrogm, chlorine, bmnrine, fluorine, iodine, or nitrogen. The camera can also react with groups made up of them UgOL The wnTTIbTT Of [wlUw jj wnniiiii Dioxins and Furana 13 784114 ENP oii303 % There a n 75 polychlorinated dibenzo-p-diaxins (PCDDs) and 135 polychlorinated dibeamfunns (PCDFs). PCDFi an similar to PCDDs in their distribution, toxic properties, and behavior, although not as much is known about them. While those dibcmo-p-diniins tad dibenxofunns with atoms other than chlorine an their comers (bromine, nitrogen, and so on) may have similar toxic potential (tens indicate this to be m e for some types), they aro not as common or numerous, and are not considered to be as important as chlorinated dibenzo-p* dioxins and dibenzofuranx. However, there has been some concern about the polybraninatrri dibcnzo-p-dioxins and dibenzofurans, ^ 1* polybrominated compounds are used as gasoline additives, and have been widely used as flame retardants in plastics, carpets, textiles, and so on (Buser, 1987). It has been shown that when these compounds are burned, polybrominated dioxins and furans can form (Buser, 1986: Kaglund ei aL, 1988). Almost nothing is known, however, about the extent of their presence in the environment. For the rest of this report, only the chlorinated dibcnayp-dioxins and dibenzofureas will be discussed Figure 3. 2A7.8-TCDD As illustrated in F igtn 3, tbs numbcs 23,73 refer to the positions on the benzene rings when the four (dm te n ) chlorine Korns we attached 2J.73-TCDD is the most toxic of the dioxins or ftatus, and csa be formed in significant amounts during the production of tricMoropfaenoMaaed chemicals. Also, 2J,73-TCDD is accumulated jtcfaendally by animal and humans, compered to the other types of dioxins sod Anns. A great deal more research has been done on 23,73-TCDD than on the other dioxins and furans, and the following rijacustinn is based largely on stadia of 23,73-TCDD. 14 Dioxins and Furans GENP 011304 -L 784115 *e r Are all dioxins tad furans daagenxts? Only 20 or so of (be 210 chlorinated dioxins and funrn are considered to be extremely toxic. These have 4 to 7 chlorines, with a chlorine in each of the 2J.7, and 8 positions (2J.7-substituted dioxins and furans). Table 1 lisa these very toxic types of dioxins and furans, aad all other dioxins and furans, along with their toxicity relative to the most toxic dioxin or furan, 23.7.8-TCDD. Table 1. Relative toxicity of dioxins and furam Conroared to the most toxic. 23.7.8-TCDD. From the USEPA National Dioxin Study (USEPA, 1987a; p 1.7) Type of dioxta or furaa 23,7.8-tetra-CDD 13 3 ,7.8-penta-CDD 23.7,8-tetra-CDF 133,7.8-penta-CDF 23,4,7,8-penu-CDF 133.4.7,8-hexa-CDD 133.6,7.8-hexa-CDD 133.7.8.9-hexa-CDD Other teoa-CDDs 133.4.73-hexa-CDP 133.6.7 3-hexa-CDF 133.7,8.9-hexa-CDF 23^4.6.7,8-hexa-CDF Other penta-CDDs 133.4,6,7 -hepta^BD Other tetre-CDFs 133.4.6,7.8-hept*CDF 133.4.7 ,9-hepte-CDF Other penea-CDFs Other hexa-CDDs Other hexa-CDFs Other hepta-CDDs/CDFs Other CDDs/CDFs (4 chlorines) (5 chlorines) (4 chlorates) (5n chlormines) (6 chlorines) "* ** (4 chlorines) (6 chlorines) (S chlorines) (7 chlorines) (4 chlorines) (7 chlorines) (5 chlorines) (6 chlormes) (7 chlorines) (1-3. 8 chlormes) Relative toxicity 1 (Most Toxic) 1/2 as toxic l/10th * " 1/23th * l/100th " " * 1/200th l/1000th 1/2300th l/10.000th l/100,000th Not toxic Dioxins and Furans IS 784116 GEIST?011305 t) T< Dioxins sod ftnans usually occur in a mixture of severil or mxny types, aod the mixture vsries with the source of the dioxins n d funns. In aider to arrive tt a nan her this lepm cnti the total toxicity of the mixture, relative 10 2J.73-TCDD, the appropriate factor is pp&ed to the amouni of each type of dioxin or funn in the mixture and the result then added, for all the types present. The total amours is then expressed in `2J.73-TCDD equivalents'. This allows the direct comparison of the toxicity of different mixtures of dioxins and funns, from different sources. For example, lex us say we have analyzed samples of soil from two contaminated waste sites, and found the following: Site One SilCTffO 3 ppb 2J.73-TCDD 6 ppb 23.7,8-TCDF 200 ppb other tetra-CDDs 1 ppb Z3.73-TCDD 4 ppb 1,23,73-penta-CDD 100 ppb 1,2J , 7,8-pentx-CDF Haw can we compare the toxicity of these two samples? The toxicity equivalent method is one way. The toxicity of these two samples would be computed as follows: Site One Factor Result 3 ppb 2J.7.8-TCDD 6 ppb 2J.7.S-TCDF 200 ppb other tetra-CDDs X I 3 ppb X 0.1 0.6 ppb X 0X11 2 ppb 5.6 ppb Sita.TffQ Faetar Result 1 ppb 2J.73-TCDD 4 ppb 123,7j8-peatfrCDD 100 ppb 143.7j8-penta-CDP XI X 0J xai I ppb 2 ppb 10 ppb 13 ppb Therefore, the toxicity of the soil in Site One i equal to 5A ppb 2J.73-TCDD equivalents and tn Site Two is equal to 13 ppb 2J,7,8-TCDD equivalent*. The USEPA used data from several kinds of studies to determine these factors (Barnes a &L, 1986). Of first importance were data concerning cancer and reproductive effects in <.nimi t*sed on long-term studies, but this information is available far only a few types of 16 Dioxins and Funns GENP 011306 784117 r dioxins and Avans. Therefore, dan from studies of tbe biochemical effects of these on cdl cultures were also used. These studies, called enzyme inducting n i receptor binding Katies, measae certain biochemical responses that are related to the toxic effects of and fdnns. The USEPA chase not to use dam from short-term miTM i tozidty **, aHng that soch information is not useful for predicting the long-term health effects of (fimma and fuians. These factors are the result of interpretation, and agencies from other countries have released somewhat different guidelines (Barnes et aU 1986). This is an area of ongoing investigation, and tbe USEPA will probably revise this table. For example, a recent study indicreea that octa-CDD/CDF are toxic, not non-toxic as this table shows (Couture et aL, 1988). Other types of dioxins and fiirans have also been investigated and found to have toxicides higher or lower than the present factors indicate (Pleuss et al, 1988a; 1988b). The use of such factors to determine the toxicity of a mixture is somewhat controversial. The CDC, far example, feels that this method is not scientifically valid, given our limited knowledge of the health effects of the many dioxins and fursns, especially in a mixture. However, Pleuss et al (1988b) investigated the toxicity of a mixture of dioxins and funns in rets, and found the USEPA's factors to be adequate for estimating the total toxicity. What factors affed the toxicity of dtoxins and frirans? The toxic effect of a dioxin or fm n oo an animal depends on more than the basic toxicity ss expertrd in the table above. It aim depends upon tbe kind of animal being epored, the of the nirn*1, md the median that tbe compoimd is mixed with. Some i n rim! of times more sensitive that others to the toxic effects af the seme dioxin or A nn. For exsmpte, games pigs (the most sensitive animal texted so far) are appruxinaieiy 3000-5000 times mom sensitive to the lethal effects of Z3,7,8-TCDD tbm tie hamsters (the more rrahxam animal so tor tested). Also, they ire very lipid-soluble (soluble in fats, ails, and solvena such as acetooe), dioxins and fursns have had a grereer toxic effect on m Dioxins and Fuians 17 784118 GENP 011307 I r animal when they w oe administered in, Tar example, cam oil, than when they woe administered in <ky food. Different kinds of dioxins and fufaaa haw different behavion within animals; some are exacted rather quickly, while others am stored in the tissues for tong poiods of time. This may affect their toxicity to the gn!ma> Laboratory stadia showed that rats and carp fed a mixture of dioxins and (ureas accumulated higher amounts of 2J,7,8-subsntuted typa (these are the mbs toxic typa of dioxins and furans) than other typa (van den Berg et a t, 1983; Kuehl et aL, 1987a; 1987b). They also found that carp retained 2J,7,8-TCDD and its counterpart furan (2J.73-TCDF) for longer periods thin dioxins a furxns with fewer or more chlorines. Researchers who have made congener-specific analyses of tissues born organisms in the wild haw also found that the 2J,73*subiDtuted congeners of dioxins and furans ire the only typa found (Rappe et aL, 1987a; Heida et aL, 1986)* Crustaceans appear to be an exception to this general rule; Rappe et aL (1987a) detected dioxin and furans congeners in crabs and lobsters that were not 2J,73-subszimted, Soils from different 2 J,7,8-TCDDecontaminated sites show greatly vreymg toxicides. Researchers bom the Nsdoosl Institute of Environmental Health Sciences and Rutgers Medical School fed guinea pigs 2J,7,8-TCDD-contaminited soils bom two different rites (McConnell et aL, 1984; Umbrcit et aL, 1986). The animals showed greatly different reactions, although the amount of 2J.73-TCDD given to them was similar. They concluded that the an tra of the soil affected the toxicity of the 2J.7.8-TCDD. prestmahly by determining bow much of the 2J,7,S7CDD was absorbed by the animal (this is known as bioavailability). The it n reften suggested thm the difference between the toxicity of the soils was earned by the difference in the amount of carbon in die soiL It is known that dioxins bind strongly to carbon red are thus le a likely to be sta rte d doing digeruinn. 18 Dioouns red R u u i GENP 011308 784119 ? W hen a n dioxins to d tarsus found? In soiL water, and air There m aren contaminated with relatively high level] (1 ppb or more) of futres; most are sites where 2.4.5-trichlorophcnol and 2,4,5-trichloropfaenal-based biocides were manufactured or processed, and/or their associated waste sites. Wood-preserving facilities (hat have used pentachlarophenol, and sawmills that have used chlorephcnolic solutions to prevent staining, can be contaminated with dioxins and furans and in some cases have contaminated the local environment. In addition, there are many contaminated areas in Missouri where 23,7,8TCDD-laden oil was sprayed an roads and horse arenas, and several military bases where Agent Orange was stored or heavily sprayed. Aprat from these recognized sites of contamination, 23,7,8-TCDD has not been found commonly in soil. As part of their National Dioxin Study, the USEPA randomly selected 221 urbre sites and 142 rural sites where no previously known sources of dioxins or furans had been recorded. Seventeen of two hundred and twenty-one urban sites and one of one hundred and thirty-eight rural sites had detectable amounts of 23,7,8-TCDD in the s l (USEPA, 1987a: pp 326-32). The limit of detection was about 1 ppt, and levels ranged from 1-11 ppt Low levels of 23,7,8-TCDD have been found in areas that were sprayed with the herbicide 2,4,5-T. During their nationwide survey, the USEPA found 23,7,8-TCDD at 15 of 26 sites where 2A3.-T w a sprayed commercially; these mes induded sugracane and rice Gelds, rangeland, and forests (USEPA, 1987k pp 3.12-21). The higbera levels (1-6 ppb in soils asediment) were generally round where spaying equipment was loaded, or where the herbicide accumulated. Where the herbicide was simply sprayed, levels woe voy low or below the limit of desearon (1-5 ppt). Dioxins and furans have also been found in sediments in the Great Lakes and some aiMciated riven, and m some large river systems near urban ccnten. They are ubiquitous in low ppb levels in the sediments of Lakes Erie, Ontario, Huron, and Michigre (Czuczwa and Hites, 1986). They have also been found in ***"** of the Niagara River (Hallet and Dioxins and Furans 19 784A 20 r\ Brooksbank, 1986), la many areas, samples of fist) or other organisms ham beea used to detect the presence of dioxin* and furans in the water ecosystem, rather than direct sampling of the scriimwus. (See the following section on dioxins and fum a in anmala and pints.) Dioxins and furans have not been detected in treated drinking water in the U.S. However, furans have beea found in tap water in Jtfm (Shiiaishi et aL, 1985) to the U.S., dioxins have been found in water of the Niagara River adjacent to the severely contaminated Love Canal area, and in groundwater near the canal (Hailet and Brooksbank, 1986). Groundwater and surface wains in the vicinity of wood-pieserving facilities and sawmills, that use chlorophenol-based solutions to treat wood, have beea nptnminanst with fnxins and furans (USEPA, 1988a: pp 53323-4). Both groundwater and surface waters can be sources far municipal drinking wiser, although the water is treated Gist Those people who live near contaminated sites and use untreated well water have beea notified. Dioxins and furans have been detected in air in urban areas of the U.S. (Czuczwa and Hites, 1986), West Germany (Rappe and Kjeller, 1987; Rappe et aL 1988), and Japan (Nakano es aL, 1987), in air near coaammazed sites in the ILS. (Pririess et aL, 1987), and in the air ifnirinn from mcmentora. It is suspected due incinerators and automobiles burning leaded gasoline are important sources of dioxins and furans in when areas. In conclusion, dioxins and furans are present in very low levels in many places, and at high lemla at a small numbs of contaminated sites, Their presence is usually associated with the production, storage, use, or disposal of chlorophenoWaaed compounds. In addition, they have beea detected in low levels in orlan area, where they am believed to be the product of nanenxa combunion procesa s. As o v ability to detect dioxins and brans improves, it is likely that they will be found in more places. An dioxin aad to v a fond la aaiaiala u d ptaxis? Dioxins and Anna are much nxm soluble in fats that in waer and therefore tend to in the fairy rissues and organ of animals exposed to them. Levels of 1-200 ppt 20 D im os and Ruaos 011310 L .. 784121 2J.73-TCDD have been detected in fish and other organisms in some p u n of the U.S., and fish from the Great Lakes and awnciatcd riven generally higher amnw than elsewhere in the country (USEPA, 1987 p 329-32). The USEPA detected 2JJ3-TCDD hi 17 of 90 samples of fish from randomly selected national monitoring sites, at levels of 1-19 ppt. Samples were also taken from 305 areas of general inteirm, chosen became they were near population cottas, were used for commercial or recreational fishing, or becrae other water quality informanoo was already available. Of these samples, 95 of 305 Grom regionally selected sites had 1-85 ppt 2,3,73-TCDD. Of fish samples from the Great Lakes, 23 of 29 had 1-41 ppt 2J.73-TCDD. The USEPA also found as much as 85 ppt 2J,7$-TCDD in fish, from riven that were receiving effluents from some pulp and paper mills (USEPA, 1987a: p 3.31). Since then, dioxins and furans have been found in the sludge, wastewater, and poducts of pulp and paper mills that use a chlorine bleaching process (Amendola et aL, 1987). A study of dioxins and furans in fish and Hening Gulls from the Great Lakes (Stalling et aL, 1983) found a wide range of total levels of dioxins (undetectable to 223 ppt) and furans (15-290 ppt) in fish from various locations in the Great Lakes watershed. 22,73-substituted congcnaa were responsible for the bulk of the Hi** and furans present, and 23,73-TCDD was the predominant congener. The two Herring Gulls analyzed had 27 and 26 ppt total furans, end 196 and 110 ppt total dioxins, including 165 and 75 ppt Z3,73*TCSD. 23,73-TCDD has alio been detected in Hening Gull eggs from the Grere Lakes, K levels ranging from 9-90 ppt (Ncrsnsm et aL. 1982). Becxxss 2J.73-TCDD is a coraarem a of the habidde 2,4,5-T, there was concern abom 23,73-TCDD befog spread tbrengh the use of this herbiddo (23,5-T is do longer produced or used in the U.5.) Therefore, a joint study by the USEPA and the University of Nebraska was to determine if am ah showed detectable aeorunx of 23,73-TCDD after normal application of 2,43-T to Oregon faresa (Gross, 1980, deed in W eoisingtn and Grass, 1985). Animal and whole M h (mice, shrews, birds, and newts) were sxnpted Dioxins and Furans 21 8 (9 and, although 3 ppt were found in several ample by one laboratory, chi* could not be confirmed by the second laboratory. However, some studies have detected low levels of 2J,73*TCDD to organisms after normal applications of 2,4,5-T. In a 1984 study by the USEPA, deer were placed in a plot that was then sprayed with 2,4,5-T (Harless et aL, 1983). They found 1-27 ppt 2J.73-TCDD in the fat, muscle, and liver tissue of the deer, and the frequency of detection increased daring the four-week sampling period. No 23,7,8-TCDD was found tn (he bone marrow of the deer, or in a deer placed in a separate area. Also, 2J3.73-TCDD in levels as high as 1 ppb have been detected in whole-animal samples of fish and shellfish from areas in South Vietnam (Baughman and Meselson, 1973) that were heavily sprayed with Agent Orange during the Vietnam War. At exceptionally contaminated sites, such as an improperly managed waste site (Heida et aL, 1986), a military base where Agent Orange was repeatedly handled and sprayed (Young and Cockerium, 1983), or where 2J.73-TCDD was released during an industrial accident (Fanelli et aL, 1980), 2J.73-TCDD has been found in many different organisms, such as rodents, insects, lizards, earthworms, and birds. Researchers in Italy found that plants grown in sail contaminated with 2J,7,8-TCDD accumulated the compound in their roots, and to a much lesser extent, in the above-ground portion of the plants (Facchetti et aL, 1986). However, in Severn, one year after the accident, no traces of 2J.7.8-TCDD were found in the flesh of fruits or in com bonds and cobs, from trees and plants grown in soil contaminated with approximately 10 ppb total dinaim. Dioxins were found in the peels of fruits; the researchers cnnclndnd that they w en wwvfwiitiwt externally by dust, and not by dioxins in the soil (Wipf etaL. 1982). Dioxins and furans have been fomd in organisms from contaminated areas, sod from fish in many areas of the U.S. Mast n a i l s do not appear to acctmulsie these compands at levels greraer than in their m ounding enviicranent, although bioconceatnooo" can occur. P in s typically contain then can pounds at levels much below the surrounding environment, and only when they are grown in highly contaminated soiL The fruits do not ^pear to contain dioxins; however, root crops may be more susceptible to contamination. 22 Diaxim and Furans 784123 s Hoir bog do dhrrin and A m as lu t la Un esvtranreaatT Many to o n influence the pertinence of dioxins and ftnoa in the envinnnaic what kind of dioxin a- farm it is, whether it is present as a solid or gas, what it is mixed with, and what kind of environment it is exposed K>, among ochre thugs. Phoiodegredation (breakdown by light) is believed to be the most important environmental process for the breakdown of dioxins and farms. Crosby et aL (1971) and Crosby and Wong (1977) have demonstrated that ultraviolet (UV) light is responsible for the photodegradation of 2J.7.8-TCDD. They also found thM the rate of breakdown varied with the material the dioxins were mixed with, and the surface to which the mixture was applied. They reported that 23,7,8-TCDD applied to wet and dry soil, or dissolved in water, showed do signs of breakdown afire as much as four days of exposure to ultraviolet light. Howevre, when it was mixed with die herbicide Agent Orange, the commercial herbicide Esteran, re a solvent such as methanol (wood alcohol), and applied to soil, glass, re plant teams, the 2^,7J8-TCDD w ts partially or totally degraded in less than eight haura. The authors noted that there conditions would often have been met during the application of 2J.7.STCDD-containing herbicides such as 2,4,5-T, and may explain why the normal application of 2 J ,7,8-TCDD-conttining herbicides typically does not leave persistent, detectable amounts of 2J,7,8TCDD on soil re foliage. In addMon to pborodegradauon. three are other processes that can break down dioxins and furaos. For example, some breakdown of there compounds in soil appears to be the result of digestion by micmorgreiigna (M toum tn and Benezet, 1973). Howevre, this breakdown occurs much mare skmty dan the pbomdegmduun process mentioned above. Efforts hi isolate a microorganism dun ere digest 2J,7JS>TCDD have met with link recceis only a small percentage of the lubaan ce is broken down, even after months of incubation. It alro apperrs that dioxins and A nns bound to pretides and dissolved in water are vrey slowly released to the atmosphere as a gas (Palrosky et aL, 1986c Nash and Beall, 1980). The significance of this Dioxins and Furans 23 L 784124 GENP 011313 process is not yet agreed upon. Once released to (be air by this process, ix is expected that Hinrin god funns are broken down by sunlight. In sum, 23,73-TCDD can be broken dawn in a matter of days in the environment, if It is mixed with the proper organic solvent (not water, but acetone or even com or olive oil) and exposed to ulnaviolet light (Wipf et aL, 1978). On the surface of the soil, without a solvent, 2J.7.8-TCDD has an environmental half-life of one year or less, due to slow photodegradatian and volatilization (Crosby and Wong, 1977). Underground and in sediments, this very stable compound has broken down much more slowly, with a half-life of about 10 yean (DiDomenico et aL, 1980a; 1980b). Very little is known about the half-lives of other dioxins and furans. In general, dioxins and furans with fewer than four chlorines are broken down more quickly than 2J.73-TCDD (Crosby et aL. 1971). The dioxin or fuian with eight chlorines is more resistant to breakdown. To what degree do dioxins and farm s spread when they are latrodneed into tbe environment? The mast important manner of transport of dioxins and furans appears to be the physical movement of panicles to which they are bound. Dioxins and furans have a gnat affinity far anpsic carton; thus they bind very strongly to the organic a rto n present in prelicks of soil, in iwdtmww, sid to the panicles found in the air. These preocJes can be lifted and c a ned by wind or by water. In the air, diarim retd Arons a n be transported ccnsjdcraMe (Usances. For instance, they have been found in the sediment of a lake on Isk Royak, an island in Lake Superior (Czaczwa et aL, 1984). It is believed that dioxins and furans could reach this lake only by tnnspon m air. Also, dioxins and Anus hare been found in Arctic seals taken in the Arctic Circle, many thottsuds of kilometers bom any known sources of the compounds (Oehme et aL 1988). 24 Dioxins and Furans GENP 011314 784125 There is also evidence of the transport of dim ins end forms in water. 23,7,8-TCDD has been detected in fish downstream from known sources, and in groundwater **1 river wim* near landfills m which large wnnrmtl of 2J.7^-TCDD-conunun*cd wretes were hi i p ^ (Hallet and Braoksbtnk, 1966). Dioxins and furans have also migrmed Cram wood-presaving facilities and snnniUs through surface waten and gremdwater (USEPA, 1988a: pp 53323-4). Measurements of the movement of 2J.73*7CDD through soil rnHiratg that tte pmem is generally a very slow one, from one to ten centimctcre per year. Palaudcy et a t (1986) reported that the initial depth to which the 23,73-TCDD contaminates the soil greatly influences the resulting movement by vapor phase. This depth of contamination is reined to the type of solvent in which the 2J.7.8-7CDD is carried: the volatility (at what temperature it evaporates) of the solvent, its viscosity (how easily it flows), and how it interacts with soil organic matter. Because they are so insoluble in water, only very small amounts of dioxins and furans are washed from soil particles or released from sediments to the water above it (Isensce and Jones, 1975). Their extremely low solubility in water makes it very hard to measure just how much dissolves; consequently, there is a wide range of reported values. The recently accepted value far 2J.73-TCDD is about 20 ppt in pure water (Marple et aL, 1986). Dioxins and furans can be transported as a gas, but Palausty e ta l (1986) detected this only at lempoaores above 30oC (877): it was therefore cooduded that this vapor phase im p o rt of 2J3.73-TCDD takes place only in upper layers of sod, during hoc weather. In <ww liniM , iw t hmmm to policies can mignte considwable in the air, and id a leaser extern in water. But these compounds are so insoluble in water, aod becaae they bind so sooogly to panicles in the soil and water, they appear to migrate very little once they reach sediments and soiL A rea of sem e conamintian have typically remained local problems, wd coraaminatian appears to be Hmiied to nearby area. Dioxins and Furans 25 784126 GENP 011315 Are dioxins and furans found is humans? Dioxins and fprans have been fond in samples of human blood and fat tissues from numerous countries, including the U.S., Canada, Japan, Vietnam, and severel countries in Europe. Based oo these findings, it is genoally agreed that the population at large in many parts of the world has been exposed to low levels of dioxins and furans. In North America, for example, 2J.7.8-TCDD is typically present in human fat, some other tissues, and breast milk, at the level of approximately 7 ppt (Ryan, 1986). In addition to 23,7,8-TCDD, pedta-CDD is typically found at 10 ppc, pentt-CDF at 16 ppt,-and the hepu> and octa-CDDs/CDFs at levels approaching 1 ppb. In humans as in other animat, the most toxic dioxins and furans, with chlorines in the 2J .7 and 8 positions, have been found in greater amounts than the other dioxins and furans with the same number of chlorines. How do dioxins and furens reach humans? Although we can be exposed to enough of these compounds to detect them in o tr bodies, the mechanisms of this process are still under investigation. Dioxins and furans are believed to reach humans in the following ways: when we inhale contaminated dust or vapors; when we contact or ingest conam bated water, sediment, or soil; when we ext contaminated vegetable, mem, or dairy products (Mukojee et &L, 1986). At the present time, the relative importance of these routes of exposure is not understood. However, drinking and cocacting contaminated wiser is generally considered a minor route because dioxins and furans have not been detected in treated drinking water in the U.Sw and our contact with untreated water and sediments is normally minimal (04. swimming, other waienpans). Ingestion of and contact with soil is also considered a minor route, except far small children. The major routes of exposure, then, a e generally "M "" to be breathing containmated panicles and earing contaminaied food. Particles in air, especially near urimn areas or large sources of combustion protects, can contain low levels of Himm and furans, and 26 Dioxins and Furans * * r the accumulated lifetime exposure from inhaling them pvuciex is considered a potentially important m ic e (Marklund et aL. 1986). Studies by Rappe et aL (1986a) and Travis and Hanemer-Ftey (1987) compared breathing to food consumption, and mibtwh th r breathing is far less important, even near a large source of combustion. However, very liaw is known about the actual amounts contributed by breathing air particles. Dioxins and forms have been found in a variety of foods in Japan and in dairy products in Sweden, and in selected foods in the U.S. They have been found in fish from the Great Lakes and associated rivers, fish from many major rivers near urban centers, and fish from rivers below some pulp and paper mills. As a result, advisories for limiting consianpuon of fish in some of these areas have been issued (see Appendix). In 1984, the USEPA found ppt levels of 23.7.8-TCDD in 3 of 85 samples of beef fat I from cattle that had grazed on land sprayed with 2,4J-T (USEPA, 1985: p 430). Dioxins and furans, but not 2J.73-TCDD, have also been found in chicken livers and chicken eggs, and in gelatin from supermarkets (USEPA, 1985: p 4*31) In both cases, the sources of the contamination were bides (from cattle, hogs, sheep, and other animals), tressed with pentachlorophenoL a product which is usually contaminated with dioxins and furans. Fat from the treated hides was used in the manufacture of the chicken feed and the gelatin (Firestone, 1973). i j Investigators in Sweden found dioxins and firms (but not 23.7,8-TCDD <* 23.7,8- TCDF) in levels below 1 ppb in cow fat. milk, cream, and liver (Nygren et aL, 1986), and investigator! in Japan (Quo et aL. 1987) found similar amounts of dioxins and furans in s variety of meat and dairy products. A researcher in Canada also found ppt levels of dioxins and furans in fruits and vegetables (Davies, 1988). 23,73-TCDD has not commonly been found in food in the U-S-; its presence in selected foods has been related to specific sources, as above. However, it is probable that trace | mounts of other dioxins and furans an present in common foods, as has been found in other countries. Similar tests have not yet been reported for the U-S. e Dioxins and Furans 27 784128 GENP 011317 Breast milk, like Easy human throes, has low levels of 2J.7T8-subgimtcd dioxins and furani, and they can be transferred to a baby through the mother's milk (reviewed in Lindstrom, 1988: p 34). B en o e a baby is tiny, undergoing rapid development, and may have breast milk as its sole source of nourishment, a breast-fed baby may be subject to a greater than nannai risk (Tarkowski and Yijanheikln. 1986; Schecter and Gastewia, 1987). Breast-fed babies may receive levels of dioxins and furans that exceed safe gniddinea (Nygrea et aL. 1986). However, a study by the World Health Organization (WHO) Regional office in Europe determined that breast-fed babies receive dioxins and furans in amounts far below what are capable of causing adverse health effects (WHO, 1988, cited in lindstrom, 1988). Young children ingest mare soil than older children and adults, and are probably subject to greater contact exposure as well (Houk, 1986). The Center for Disease Control took this greater exposure into account when they determined that 1 ppb or more of 2J.73-TCDD in the residential soil of Times Beach suggested the need for corrective action. Workers in several occupations are or have been subject to a greater potential exposure (Choudhary, 1983). These include: milli where wood is treated with perttachlaophenols or where treated wood is sawed; leather and tanning industries, which have used chlorophenols as preservatives; facilities that manufacture, ship, or formulate chlorophenols; pulp and paper mills that use chlorophenol-based fungicides; health-related facilities, where hexachlorophene is used as a baom dde; occupations where warfare apply chlorophenol-based biocides. In sum, it is generally believed that eating contaminated food and breathing contaminated pmttdes are the most important sources of exposure. We need to know mote about the routes of hmMH to <timiM vt fum s. Also, breast-fed m il children, and some w ukns in the indusries that use contaminated products, are subject to greater than normal potential exposure. There cases merit special attention. 28 Dioxins rod Furans GBKP 011318 A SOOTCM of Dfovh ad gitran* How an digital tad fluwn created? Dioxins w d finnis have no useful puipoao rod have never twgi mxmikmired deliberately, except in small amounts for research ptapoaea. They m t known b be created cn two major ways: (1) they an created in trace quantities by unwanted side reactions, which take place during the chemical processes used to manufacture useful products such as biocides, paper, disinfectant!, and preservatives; (2) they are aeated when a substance containing chlorine a burned, or when a sabmnee is burned in the presence of chlorine (chlorine is a in** element of nuny substances). In addition to the dioxins and forms bom these two major sources, there is evidence due dioxins and forms can be created when catain mixtures of substances are exposed to sunlight. The importance of this process is not yet known. Detennming the relative or absoltae tmpom a ce of the various sources of dioxins and fo n u is comp!rated. Simply, the question t Whm kind of hazard does the source represent to human and other organisms? In order to estimate this, it least the following information should be considered: 1) What types of dioxins and forms are produced by the source? 2) What amounts of the different types are produced? 3) How will human and her organism be exposed? - Par how long? To whtt levels? 4) How many humans or other <*!* will be exposed? Because this frrfnumrinM is uomilable far mast of the sauce of the dtem s and fmatu, it is igposrible to maks man than a ludim eaay qualitative carimme of the imparlance of dm various sources, (dative to each other. Ft* son sources, even this' is unwarranted of lack cf infornucioa. Tharfore, while a rttanaon of the sauces is werdtwhile, it should be noted that the various known sources may prove to be much more or less important Dioxins end Furans 29 784130 GENP 011319 than our present understanding makes them appear. Also, new sources of dioxins and fuians will continue to be identified. I What products e u be contaminated with dioxins and farm s? Dioxins a n formed as unwotted byproducts during the manufacture of some chlorophenols (especially those with three or more chlorines), and during the manufacture of chemical products that are derived from these chlorophaiols: phenoxy herbicides such as 2,4,5-T, and biocides and preservatives such as pemachlorophenol. Manufacturers have greatly reduced the levels of dioxins and fuians in their chemical products since they were identified as contaminants in the early 1970s. In some cases this resulted in much higher concentrations of dioxins and furens in the waste from these processes. The safe disposal of such waste is difficult, and inadequate disposal methods have resulted in environmental contamination. Dioxins and/or firm s have beat found as contaminants in the following products: I \ i | Table 2. Products that can be contaminated with dioxins and/or fmans Product Contaminants PCBs hexachlorophene 2 .W 2,4-D chlorephenols with 3 or more chlorines polychlorinated benzenes diphenyl ctba herbicides h n a d itorocyciohexane p^ier products Furens Dioxins* Dioxins* Dioxins* Dioxins and Furens * I could find no analyses of there products far firm s. Nate: The above list is based on information available in journals or reports. Under the auspices-of the Toxic Substances Control Act (TSCA), the USEPA published s larger list of chemical products that may be contaminated with chlorinated or terminated dioxins and furens (USEPA, 1987b). For more inftymarion, see under 'What has been done about dioxins and firm*?", p ^ e 69. I ] 30 Dioxins and Furens l GENP 011320 784131 1, r PCBs PCBi and PCB-conuining mixtures can be a scarce of funns and to a lesser <*" a source of riifflum. They were widely used [liar a 1977, primarily as dielectric fluid in electrical equipment such as transfannen and capacitors. PCBs have also been used as plasticizers, bydmilic lubricants; and in a variety of other applications. PCBs are no longer produced in the U.S. or installed in new equipment, and their use and disposal is restricted (see under 'What Has Been Done About Dioxins and FuranS?", page 69). Levels of furan contamination in PCBs vary with the manufacturer and the type of PCB (Bowes et al,, 1975; Rappe and Buser, 1980). A recent and particularly sensitive study of both U.S. and Japanese PCBs found up to 60 different kinds of funins, including most of the 23,7,8- substituied types, in low ppb levels (Wakimoto et aL, 1988). No dioxins were detected above the limit of detection of 2 ppb. Used PCBs can have higher levels of (mans. Apparently, the heat that they may be subjected to daring use can promote the Amber formation of funns (pen. comm., PJL des Hosiers, USEPA). However, several studies have shown that simple overhearing or arcing in electrical equipment does not generate Anans (des Rosiere, 1987). While dioxins generally have not been detected in PCBs, a recent study found relatively high levels of dioxins in used oil (R. Adams, et aL, 1986). For many applications, such as dielectric fluids, PCBs are combined with other compoinds such as chlorinated benzenes. These other compounds are believed to be responsible far the presence of dioxins (see discussion of chlorinated benzenes, below). Appmximaeiy 1.4 billion pounds of PCBs were purchased by US. industries prior to 1977. Based ao these sales, an **""--* 84-94 kilograms (kg) of fumts were jxeaent in the PCBs produced during this period, including 8 kg of 2S.7S-TCDF and 14 kg of 2J A 73-penx*- CDF (Humnger et aL, 1985). The authors noted that the were underestimates, because of missing sales information far some types of PCBs. Most PCBs have been incinerated by licensed hazanlous waste facilities or buried in landfills. However, a January 1988 U.S. General Accounting Office report estimates that 312 ponds of PCBs still remain in millions of pieces of electrical equipment in the Dioxins and Funns 31 784132 U.S., and dot as much as ISO million pounds of PCBi have been released to the enviionmeot (pen. coouil, USEPA). Low levels of PCBs are now ubiquitous in the environment, snd it may be presumed that they are contaminated with trace levels of furans. In areas that are heavily with PCBs; it may be presumed that forms are present as welL Based oo a comparison of the furan cotgenera in the tissues of aquatic animals (a snapping turtle, seal, and killer whale), to the furan congeners present in PCBs, several authors have concluded that PCBs were the source of the furans in the tissues (Rappc et al,, 1981; Wakimoto al,, 1988). The release of PCBs is now highly restricted, and they are probably no longer a significant source of new releases of furans (the uncontrolled burning of PCB-containing fluids can be an exception; see "PCBs" on page 39). Hexachiorophenc Hexachlcxophene is a bactericide used in special soaps, veterinary medicine, and in restricted fashion as a surface disinfectant. It was once widely used in hospitals, in the cosmetics industry, and in some consumer products such as baby powder and skin cleansers. The USEPA no longer allows its use in non-prescription products. Very few measurements of dioxins in hexncfalorophene have been made, but levels of from 02-05 ppb 2J.7.8-TCDD were found in three samples (Baughman, 1974, cited in Rappc, 1984). Present levels have been reported as equal to or less than 30 ppb (USEPA, 1985: p. 4.12). Hexachiorophenc is currently not produced in the U 5. (USEPA, 1986: p 3.16). 2.45-triclarophenoivace&c arid 0.45.11 The herbicide 2v45-T was used widely in the U 5. before 1980; and in a restricted fashion an il 1983. It is no longer produced or used in the U 5. Dioxin concentrations as high as 100 ppm were fowd in 2w45*T produced in the 1950s and 1960s, with an rgitnatrrl average of about 1 ppm (Rappe et aL, 1982: p 496). 2J.73-TCDD was present in greater concentration than other isomers4 (Rappe, 1984). When this contaminarirw waa verified in the eraty 1970s, * An isomer is a single member of a homologue; a bomologue is that group of dioxins or furans with the same number of chlorines. 32 Dioxins end F inns J L GENP 011322 784133 r manufacturers lowered the level of contamination considerably, and in 1984 pmdum i of 2,4,5-T reported that the levels of 2J.7.8-TCDD were below 0.1 ppm (JUppe, 1984). The authors of one study estimated this maximum amount of 2J.7.3-7CDD (hat could have been present in 2,4,5-T produced from 1960-1970 (Hutzmger et aL. 1985). Baaed oo total 1960-1970 production of 48.2 million kg. and a maximum concentration of 100 ppm 2J.7.8TCDD, they estimated a maximum total of 4800 kg 2J.7.8-TCDD present in 2,4,5-T. The authors added that after 1970. both the level of contamination and level of production dropped sharply. The defoliant Agent Orange, which was sprayed heavily over most of South Vietnam during the Vietnam war, was composed of a 50:50 mixture of 2,4,5-T and 2,4-D. Levels of 2J.73-TCDD in Agent Orange were found to vary between 0.02 and 54 ppm, with an average of 2 ppm (reviewed in Esposito ct aL, 1980: p 98). The very heavy spraying of South Vietnam resulted in significant contamination of the environment with 2J.73-TCDD (Baughman and Meselson, 1973). In the U.S., nomal spraying with 2,4,5-T appears to have contributed only trace levels of 23,73-TCDD to the environment, presumably because the 2J.7.8-TCDD is present in a solvent (2,4,5-T) and therefore can be quickly broken down by sunlight. However, it is possible that the use of 2,4,5-T contributed to the low background levels of 2J.7.8-TCDD in the fat of persons in the U.S. The herbicide 2,4.5-T is no longer produced or used in the ILS and is therefore no longer a source of dioxins here. However, a large amount of cantam ined w ots w n created during the production of 2,4,5-T, resulting in many contaminated manufacturing rod waste disposal sites (USEPA, 1987a), Some of these sites are still consibramg dioxins to the environment, predominantly the local area (see *Wh*i about dioxins and furana from sewage plants, waste streams, and landfills?", page 45). 2.4-dlchlotoohenoxvncetic acid 12.4-D1 The widely teed herbicide 2,4-D is made from dichlorophenoL Dichlarophenol ho only rarely been found to be contaminated with dioxins and futans, and 2J,73*TCDD is not D rains and Farms 33 784134 OBKP0U323 formed in the manufemm of 2,4-D. However, other, much less toxic dioxin congeoos have been found in 2,4-D at levels of from less than 1000 pfin to less than 10 ppm total dioxins (Cochrane et aL, 1982). The authors of this study sulyxed 2,4*0 as acid, ester, and amine formulations. The ester fonnuladons contained the highest levels of dioxins. The majority of the Hintn congeners identified in 2,4-D by this srndy and others are considerably less toxic than 23,7.8-TCDD (e. 13,6,8-TCDD), or not toxic (dioxins with 1-3 chlorines). While the dichlorophenol from which 2,4-D is derived is not normally contaminated with 2J,7$-TCDD, isolated cases of 2,3,7,8-TCDD contamination 'of 2,4-D may have occurred when equipment formerly used to process 2,4.5-T was used to produce 2.4-D (USEPA, 1986: pp 3.21-3.23). The contaminated equipment would not be expected to contribute mere than very tow levels of 2J.7.8-TCDD in the first few batches of 2,4-D. In Canada, an annual production of 8 million kg of 2,4-D was estimated to be the source of 9 kg of dioxins with bom 2-4 chlorines (Tosine, 1983). In the U.S,, 7.1 million kg of amine fansulatians of 2,4-D were produced in 1986, and 6 million kg sold (U.S. Department of Commerce, 1987). No ester formulations wen produced in (he U.S. in 1986, but 3.7 million kg were sold. Because the level of production is amiUr to that in Canada, 1 assume it to be the source of a similar amount of dioxins. As in 2,4,5-T, dioxins in 2,4-D are present in a solvent (the herbicide) and therefore may be broken down by sunlight soon after their application. This possibility, along with proper dhpoal of the wastes bom the production of 2,4-D, make it probable dot the production of 2,4-D is a relatively unimpanant source of dioxins in the eavnonmeaL Chlmonhenols Chtaropbeaoli are a principal ingredient in the processes used to manufacture many of the above chemicals. They or their derivxtrvci are used to preserve wood and drilling muds, and as btoddes for process and cooling watea in some industries. Some of these uses may be phased out in the near future. In the p et, chkxcphenols and their derivatives have beat used to preserve hides, textiles, prints, glues, and other materials, as disinfrciants. and as biocides in fluids that aid in the anting of metals. 34 Dioxins and F im a i i I GENP 011324 784135 r Chloropbenols with one or two chlorines (chlorophenol and dichlaropfaernl) have m dy been found to be cootamimied wiib dioxins or funns, Chloropheools with three or more chlorine* have been found to be cantanmatrd with many congeners of rfimb ftnua, and 2^4,3-trichloropbeuol is always contaminated with 23,73-TCDD (pen. comm., Rolf Hactmf, Umveniiy of Michigan). Chloropheools with four or fewer chlorines are oo longer produced in the U.S. (pas. comnL, John Wilkinson. Vulcan Chemicals). There is only one current manufacturer of pcniachfarophenol in the UJS- and penischlorophcnot and a product made from pemachlorophenol. sodium pentachlorophenate, are used almost entirely to preserve wood or prevent wood saining (USEPA, 1986; pp 3.17-21; USEPA, 1988a; pp 33286-7). Pemachlorophenol has been commercially produced by two basic methods: the hydrolysis of hrrachlorobemene or the direct chlorination of phenol (Esposito al. 1980: pp 78-88), Although both methods result in the formanon of dioxins sod farms, the hydrolysis of heuchlorobenzene can result in higha levels of dioxins and farms that are of most concern. In the U.S,, pemachlorophenol has always beat produced by (lie direct chlorination of phenol (Esposito et at, 1980: pp 78-88). The USEPA has reported that solutions of U.S.-produc*d pemachlorophenol in use at wood-pieserving facilities avenge approximately 300 ppb total dioxins and furans, in 23,7,8* TCDD equivalents (USEPA, 1988a: p 33301). 23.7.8-subaituied hetu-CDDs me responsible for mast of this toxicity, and in the past were thought to be responsible far pentachlorophenai's demonstrated toxicity. However, the results of a recent btoaiay (NTP, 1988) showed ih a pcnochlnrophenol alooo is a crecinofen far mice, and the presence of 10 ppm heu-CDDs in the penachlnrophenol made litxie or no difference. 23,73-sabcihrted dioxins and finns with fewer than six chlorines are present in pentachlorophenol only at very low detectable levels or below the limits of detection. Ten-dioxins, inclining 23,73-TCDD, have not been detected in numerous analyses of U3.-produced pentachlorophenol (pen. comm., P . des Rosias, USEPA). A recent aid puticulirty sensitive -analysis of 10-year old pentachlorophmoli and sodium pcntachlcrophenaics. manufactured in Europe by the hydrolysis of bexachlorobetnene. Dioxins and Furxns 33 784136 G E N F o il round very low ppb and ppt levels of 23,73-subarituted te n - tad penta- dkgins sod fisans, in to 2J,73-subsdtuted dioxins and futsns wilfa six or more chlorines (Hxgenmiier sad Brunner, 1987). However, the low levels would lave Hole impact on the cstrmaiwd overall toxicity of the products; U would not differ significantly fiom (ha of US.-produced pentachlorophenols. Hageomiaer and Brunner (1987) postulated that, in West Germany, the production and | use of pemachlotophenol and sodium pemad ilorophenate may be, or have been in the past, the predominant source of dioxins and funns in their environment. The USEPA considers the wastes from wood-treatment facilities and sawmills to be sources of significant environmental contamination, and for that reason has regulated or proposed to regulate such wastes as hazardous (see "What Has Been Done About Dioxins and Furxni?', page 69). It should be pointed out that alternative wood preservatives (creosotes and im gznic arsenicals) are considered human carcinogens (USEPA, 1988a), and a study by Czrnegie-MeUoa University concluded that pentachlorophenols are the safest wood preservatives available (Camcgie-Mellon University, 1982). Chkxuphenols, especially 2.4,3-trichlorophenol, were protably sources of large quantities of 23,73-substituted dioxins and furani in the p u t (Thame, 1983; Hutringer, 1983), i and many contaminated sites remain from this era. However, levels of ehloropheaoi production I and contamimrion have been greatly reduced Baaed on a total antral production of pentachlorophenol in N oth America of 11 million kg (USEPA, 1988a), and an avoage 2 J.73- TCDD- equivalent content of 300 ppb, dda production would be the source of 3J kg of 23,73TCDD equivalent! annually in North A an c a. M os of this amount is present in used pentKhlarapheaai, and U incmemed u a (ozantoa wane. PftlyrhWinufijd bCTPffPO Itotychlarinatad benzenes have been used u biocides, solvents, and in electrical and chemical industries. They were often mixed with PCBs in dietearic fluids. Dioxins md fu ras have been found in some cfalorebenzroes a ppb and ppm levels, aithnwah no infimnarion is avtilablB on the specific types (reviewed in Hefaufl aid H utrifl^r, 1986). 36 Dioxins and Furani GENP011326 Diphenvl ether herbicide! Diphenyl ethrr herbicides can be derived from trichlorophcnol and a variety of and furans were found in three types of dipbenyl ether herbicides in one study (Yanugishi et aL, 1981, died in Rappe, 1984: p 83a). Total concewmion of dioxins and furrea ranged from le a than 2 ppm to about 50 ppm. No 23,7,8-TCDD was found and the few individual congeners that were identified are not considered very toxic. Hexachlomcvclohcaane Hexadilarocyclohcxane is used primarily to produce the insecticide Lindane. Dioxins and finns are apparently formed by this process, and the waste has been found to be contaminated with ppm levels of dioxins and furans, including ppb levels of 2J,73 -subsdttned congeners (Scfaolz and Engler, 1987), The significance of this source is not known. Pacer mills and products Pulp and paper mills that use a chlorine bleaching process have been identified as sources of rfimiM and furens. Dioxins and furans are believed to be formed when naturally occurring phenolic compounds in wood called lignins react with chlorine during the bleaching operations in the manufacture of pulp (Beck et aL, 1988). A preliminary study by the USEPA and the pulp and paper industry of five pulp and paper mills that use a chlorine' bleaching process, found that the wastewater effluent from these mills had concentrations of less than 1 ppt total dioxins and furans, arid the sludge had concentrations of less than 1 ppb total dioxins and furans (Aroendota et aL, 1987). Bccreae of the large volume of effluents from pulp and p^ter mills red the pormtial for the accumulation of dioxins and finns in organisms, even these low levels may pose significant risks to orgmusms exposed to the effluents. As noted earlier in this report, low levels of 23,73-TCDD were found in fish Aw m im bi from some palp and paper mills and these findings are of concern to people who eat fish from these waters. The USEPA and the pulp red paper intfcisuy have a mare extensive study undaway. Researchers in Sweden determined that the isomeric pattern of dioxins and finns from pulp plants is ezsily distinguishable from that of tfioxins and furans from incinenton (Swanson Dioxins and Funms 37 784138 ci a l 1988). They found tint crabs and sediments near (he pulp mill had dioxins and finals with m igfftteric pattern in!-to that in pulp, which then changed to the incinerator patera as they moved sway from the tnilL Hie authors estimated that the pulp indosry m Sweden was a source of 5-15 grams of 2J.7.8-TCDD equivalents per year, and reported that the Swedish EPA l kg of 2J.7.8-TCDD equivalents per year for all sources at dioxna and fimns in Sweden. A study of West German paper products such as newsprint, coffee fillers, and recycled paper found that they can contain a variety of farms of dkutins and fimns. Total concentrations of dioxins and funins were below 1 ppb with concentrations of the more toxic congeners at levels below SO ppt (Beck cl al., 1988). A study sponsored by the National Council of the Paper Industry for Air and Stream Improvement (NCAS1) determined that comart with paper products poses an insignificant health risk to humans (NCASL 1987a). However, studies by researchers in Canada suggest that cardboard cartons made of bleached pulp can transmit dioxins and fiirans to certain food products, such as milk (Ryan et al, 1988). Any such assessments include a large number of uncertainties, and further research is necessary. What products can produce dioxins and fiirans when they a n burned? Dioxins and fimns can be fanned when many materials camming some film of chlorine are burned, or when certain materials are boned in the presence of chlorine; The amount and kind of dioxins and fimns prodoced varies greatly with the race and condition. 38 Dioxins sndTurans L 784139 The following chlorinated product! can all produce dioxins andAv furans when burned. Table 3. Chlorinated products that catumduce dioxins and/or fumu when burned Product Contaminants PCBs potybromina^d biphenyls (PBBs) polybrominaied diphenyl ethers (PBDHs) polychlorinated diphenyl ethers (PCDEs) chloropbenols tetrachloroethylene polychlorinated benzenes polyvinyl chloride (PVQ Leaded gasolines F rau Diaxina and Rums '' " * "` *" ** Nate: When a material is burned in the laboratory to determine whether it is capable of producing dioxins and fitians, it is typically burned under those conditions most likely to produce dioxins and furans, or that produce the largest quantity of dioxins and furans. Therefore, the same substance may produce much smaller amounts of dioxins and furans under the uncontrolled conditions rtf a fire, or in the highly controlled conditions of an incinerator. PCBs PCBs are fire-resistant, compounds and do not readily support combustion. However, if they are incompletely burned in fires fueled by o d n materials, furans may be formed. More thin 1 ppm of each of the most toxic congeners of furans (4-7 chlorines -and 23,73 positions filled) have been produced by burning PCBs in the laboratory (Erickson et xL, 1984; Swenson et aL, 1985). Fires involving electrical equipment have contaminated buildings and other places with soot containing as much as 5000 parts per million total furans, including low ppm levels of 23,73-TCDF (Erickson et aL, 1984; Rappe et aL, 1983: p 121). In the U.S., PCBs are no longer produced or used in new equipment, and PCB-containmg equipment in buildings is subject to stria regulation. However, bsgo mashers of transformers and capaciiore with PCB-comaminaccd dielectric fluids are still in use, and these contantinaicd dielectric fluids can produce furans when they ran burned (Nanug et si, 1988). Pnlyhrnmin*ri and potyfaronrinaied dlnhenvl ethers ffBDPEsl Polybrominaied biphenyls (PBBs) and pofybrominxied diphenyl etfaen (PBDPEs) have been widely used as flame reraidants in textiles, carpets, and plastics. Although the addition of these substances makes products such as ckxhrng and carpets lea susceptible id igniting, the materials can bum in a building fire or mctnenior. When tuned in the tabonimy, they have Dioxins and Furans 39 784140 GENP 011329 produced bnxninatcd dioxins and Tunns, and smaller amounts of chlorinated dioxins and furans if they are burned in the presence of some form of chlorine (Buser, 1986; 1987; Thoms et aL, 1987). Polychlorinated diphenyl ethers (PCDEs) Polychlorinated diphenyl ethers (PCDEs) are used as herbicides and have been found as low-level contaminants in chlorophenols (Soikkeli et al., 1986). When burned in (he laboratory, (hey can produce significant amounts of dioxins and furans (Rappe, 1984: p 83a). Chlorophenols When burned, chlorophenols can produce significant amounts of dioxins and furans, especially those with from 4-6 chlorines, and including the toxic 2J.7.8 congeners (Rappe et ai, 1978; Rappe et aL, 1983: p 108). An unknown amount of chlorophenol-treated wood is eventually burned, and may be a widespread source of significant amounts of dioxins and furans. Current USEPA registration for pentachlotophenol used in wood treatment specifies that the wood is not to be burned, although wood-treatment facilities may bum wood soap in hightemperature boilers. One study found that levels of octa-CDD were doubled when PCP-treated plywood was burned, and dioxins with six and seven chlorines were also detected (Crosby et aL, 1973). Wood-treatment facilities often collect waste pentachlotophenol in ponds, and in the past they periodically set fire to the ponds to reduce their volume. This practice generated large amounts of dioxins and furans (P.E. des Rosters, USEPA, coed in USEPA. 1986: p 3-18). TetachloroetfiYlcae and polvchlonnaied benzenes Tetrachiorethylene and polychlorinated benzenes are used as cooling fluids in electrical equipment, often in combination with PCBx When bunted in the laboratory, they can produce furans and lesser amounts of dioxins, including the mo toxic congeners (Erickson et aL, 1984). Polychlorinated benzenes produced less thsn l/10th the amount of furans produced by PCBs, and tetrachioroediylene produced less than 1/1000th. However, these are significant amounts nonetheless. Far example, polychlorinated benzenes are believed to be responsible for the dioxin contamination of an office building in Binghamton, New York, after a transformer fire. ( i 40 Dioxins and Furans GENP 011330 784141 The soot produced by this fire had 20 ppb tool dioxins, including 0.6 ppb 2J.73-TCDD (Rappe et aL, 1983: p 121). Polwinvl chloride fPVCl Polyvinyl chloride (PVC) is a common plastic. When burned in the Ubamory, it cat produce low ppb levels of dioxins and funns (Maridund et aL, 1986: p 900. Lege mm* of PVC plastic are present in municipal waste, and are suspected of contributing to the (fowiM and futans emitted from incinerators. Leaded gasoline Low levels of dioxins and funrns have been detected in motor oil and in the whin 0f can that use leaded gasoline (Marklund et aL, 1987), but not can that use unleaded gamimn The authors noted that dioxins and funns may be destroyed in the catalytic conveners of the can burning unleaded gasoline. Dioxins have been found in mufflers from diesel tracks (Bumb et aL, 1980), and dioxins and funns have been fotmd in motor oils that are recycled from used motor and other oils (Rotaid et aL, 1987). Dichloro and dibromo ethane (DOE and DBS) are used as additives in leaded gasolines, and are thought to be the precursors to dioxins and futans. Leaded gasoline is a very widely used product, and therefore even the low levels formed are potentially important. It was estimated that autos burning leaded gasoline in Sweden produce emissions with a total of 10-100 grams of 2J.7.8-TCDD equivalents per year (Marfclund et aL, 1987). Using their values (30-540 picogiams of 2J.73-TCDD equivaterusAilometer) and assuming their tea auto* avenged 20 miks (32 kBometen) p v gallon of gasoline (the models were a Saab 900, a VW Golf, an Opel Kadeo, and a Volvo 245), total emissions from ILS. autos can be estimated. Based an xn average figure of approxinutely 57 million gallons of leaded gas usdd per day in 1988 in the U.S. (pea. comm., American Petroleum Institute), and the values above, autos burning leaded in the U.S, may produce emissions with from (57 million gaikmVday x 365 days x 32 tiianeterVgallon x 30 pkograms/kilometer) to (57 million galkmstfay x 365 days a 32 kUometer/gaHon x 540 picogramsflrikxneier), or 20 to 360 grams of 2J.73-TCDD equivalents per year. The use of Dioxins and Funns 41 784142 ftp leaded gasoline is steadily decreasing in the U.S, and much of Europe, thus rakicxng the contribution from this source. The burning of dioxins and furana The incineration of dioxins and furans in the laboratory has produced other dioxins and furana with fewer chlorines. For instance, incineration of oca-CDD or octa-CDF can produce dioxins or furans with from four to seven chlorines (Marfchmd et al, 1986; Swanson et aL, 1986). This is a potentially significant process heeane the toxicity of dioxins and furans generally increases as the number of chlorines decreases from eight to four. Also, octa-CDD and octa-CDF are often the most numerous types of dioxin or finan in contaminated products or waste. f Does the burning of paper, wood, peat, or coal produce dioxins and furans? i Several studies have shown that wood, peat, and coal can produce and furans when they are burned. Apparently, naturally occurring phenolic compounds in these substances (lignins) can react with naturally present chlorine to form chlorinated phenols, which then form dioxins and furans (Beck et al., 1988). Measurements of dioxin and form emissions from coal- and peat-fired power plants indicate that they emit only very small amounts of dioxins and furans, perhaps in part because the combustion conditions are carefully controlled for high efficiency (Kimble and Gross, 1980; Markltnd et aL, 1986: USEPA, 1987a: pp 4,1-26). Likewise, the combustion of paper has been found to produce only very small amounts of dioxins and furans (Otis et aL, 1982; USEPA, 1987a: pp 4.1-26). The combustion of wood, on the other hand, is a potentially significant source of dioxins and forms. Dioxins and furans, including the moa untie congcacn, have been detected * in small amount! in emissions from wood stoves rod wood boilers (Nestrick Hid Lam pnki, 1983; USEPA, 1987a: pp 4.1-26; Tboma. 1988). of the large number of wood combustion sources in the U.S,, this could be a significant source. However, analyses of lake sediments from an island in Lake Superior did not find dioxins and forms in sediment layers 42 Dioxins and Furans j j I I l ; i ! I j. j | i j GENP 011332 784143 r to n before 1940, hen wood cornbusioa was prevalent in North Am oks (Cztczwa and Hites, 1986). Wood that has been treated with pentachloropbenol or sadism penachlorophenrae would be especially likely to emit dioxins and farms when burned. However, the nmjgr use of pentachlorophenol is far the aeatmera of utility poles, and few if any are burned in wood stoves. Do municipal incinerators produce dioxins sod farm s? Municipal solid-waste incinerators are recognized as important sources of dioxins and furuu. They are found on the dust and in the gas emitted through the stack; on the fly ash and bottom ash that is collected and placed in landfills; and in the scrubber water that is part of the emission control system (Mufclund a aL, 1986; USEPA, 1987a; pp 4.1-26; Hiroika et aL, 1987). While municipal incineraton have been found to produce all types of dioxins and furans (Kiiasek and Hutzinger, 1986), the amounts and distribution of the different dioxins and fmsns produced by municipal incineraton vary widely and therefore so do estimates of the amounts of dioxins and furans produced in total by municipal solid-waste incinaauon. Incineraton operated under the proper conditions and equipped with the most modem emission control devices have greatly reduced dioxin and furan emistinm (Hay et aL, 1987; USEPA, 1988b). Rappe a aL (1987a: p 1604) rarimata that a normal-sizsd municipal solid waste incinerator (which bums 50,000-200,000 tons of gartwgo per year), operating under nonnal condiliooa, emits through the stack MOO grams of 2J.7.S-TCDD equivalents per year (based on a range of MOO runogrxms of 2J.7.8-TCDD equivakats per cub meter of stack effluent). This figure can thus be interpreted as 5 milHontht (1/200000) to 2 thousandths (100/50000) of a gram of 2J.73-TCDD equivalent emitted through' the sack per ton of strings burned. According to a recent USEPA report (USEPA, 1988b), 16J million tons of gvtaage are incinerated in the U.S. each y es. Using Rxppe's range as given above, mmidpal indneaun in the U.S. may be the source of to n (5 x 10-6 gnmsAon x 16J x 1(P tons) to (2 x Iff* Dioxins and Furans 43 784144 GENP 011333 r grama/um x 16.5 x Iff tons), or from 0.0825 to 33 kg of 2^,7,8-TCDD equivalents per year, | i]innhniw< in ihdr stack c01uenu. This caimree does not take into accouni die dioxins and furaas in the bottom ash, fly ash. and scrubber wrere, the majority of which am placed in landfills, in Canada, dioxin and fuian emissions to n municipal intinenton has been estimated to be 63 kg/ycar TCDD equivalent in die fly ash, and 6.1 kg/yar TCDD equivalents in the slack emissions (Tosine, 1983). A study in Switzerland showed that levels of dioxins and furans in cow milk were higher in samples collected near incinerators (Rappe et aL, 1987b). However, in another study (Rappe et al., 1987c), the authors mention that while Sweden has 25-30 incinerators and Yugoslavia has none; similar levels of dioxins and furans are found in human milk to n these countries. Apparently, incinerators are only one of many sources that contribute and furans to the environment in these countries. Do other large combustion sources produce Hfarina and ftirans? 11161 are other potentially large combustion sources of dioxin and furans. Hazardous and hospital waste indneraton, sewage sludge inemooton, and smelters and mills that recycle metals can all produce significant amounts of dioxins and furans, including the more toxic types (USEPA, 1987a: pp 4.1-26; Clement et aL, 1987; MsUimd et a l, 1986). The dioxin and fuian emissions from other large combustion sources have not been as well studied as those to n municipal indaetatax The available data indicate dire the emissions to n a hazanfaus waste or sewage sludge incinerator are of the same magnitnde as a municipal incinerator (USEPA, 1987a: pp 4.1-4.25; Tsnji a aL, 1987; Cement et iL, 1987). Because three are many more large industrial combustion sources than munidjal memreaton, their total renisiioni of dioxins and fltians could be greater than to n municipal tncina i ina (Rappe, 1987). 44 Dioxins and Furans OENP 011334 784145 r What about dioxins and furuts from sewage plants, m a tt streams, and (todflUs? Dioxins and Tunas have been found in sewage sludge fit mmriripji waste-water treatment plants in Germany, in levels below 100 ppb (Hagenmaier et aL, 1986). The tfwi? varieties of dioxins and furans were present a levels below 1 ppb. Based on an analysis of the ratios of the various congeners of dioxins and finos present, the authors preposed that peatachlorophenot and its derivatives are the source of most of the dioxins and furans in the sludge. In addition to the products themselves, the waste generated by the production of chlorophenoi-based products is a potentially important source of dioxins and furans. Ironically, the contamination of the wastes is thought to have increased significantly as a result of efforts to reduce the contamination of the [ducts: the dioxins and furans were concentrated further in the wastes. Landfills that contain the wastes from the manufacture of chlorophenols and chlorophenol'based products, that contain PCBs, or that contain fly ash, are suspected sources of dioxins and furans. The Love Canal and attnriaterl chemical landfills in New York, fa example, have contaminated the adjacent Niagara River with dioxins, and the Venae manufacturing and waste-disposal site in Jacksonville, Arkansas, has contaminated the nearby Bayou Meto and Arkansas River. Also, sites where chlorophenols and chtorophenoUbased products were manufactured or processed are now considered sources of dioxins and furans (USEPA, 1987a: pp 3.1-26). As a remit of these incidents, wastes conaming dioxins and furans have been disposed of much more carefully. ( t Are there other processes that create dioxins and furans? It has been shown that dioxins rod furans can be broken down by sunlight (this is called photolysis) to other types of dioxins snd furans with fewer chlorines. For exsmpie, the octachlorodioxin (OCDD), when exposed to UV light, can be broken down to potentially more toxic dioxins with fewer numbers of chlorines (Crosby et al., 1971). Combustion processes Dioxins and Furans 45 784146 GENP 011335 often prodtKe greater amounts of octa-CDD than all other dioxins combined, and it is often the most common dioxin in chlorophenols. However, the photolysis would then be expected to continue, eventually breaking down any toxic varieties into much less toxic forma. Photolysis can also form dioxins and furans horn other compounds. It has been shown that a mixuse of polychlorinated benzenes and phenol, when exposed k>UY light, cat produce furans (Choudhaiy et al,, 1983). Both polychlorinated benzenes and phenols are common environmental contaminants. Also, the photolysis of chlorophenols has been shown to produce octa-CDD (USEPA, 1985: p 4.17). Thus, wood and other materials preserved with chlorophenols and exposed to sunlight may result in the formation of rfiniimx The significance of these photochemical processes is not yet known. Conclusions on sources of dioxins and farras There are many sources of dioxins and furans. Some of them, such as souces of combustion, are widespread and numerous. Others, such as contaminated nunufreturing and waste sites, are fewer in number and usually local problems. The significance of the photochemical processes that can convert less toxic compounds to din* and furans is not yet known. Also, the relative importance of what appears to be the two major sources of dioxins and furans (chlorophenols and chlaropbenof-faesed products, and sources of cambtstim) is not yet known. It is generally agreed that dioxins and finara in our environment come primarily from recent human activities (chemical protection and ore, manen don, automobiles). Cznccwa and Hites (1985) analyzed sediment cores from the Great Lakes and a Lake in Switzerland. Dioxins and furans in these sediments were at or below the limit of demotion tiltil they reached tbo layers deposited a t o approximately 1940, a time that they say corresponds to the beginning of laigMcale manufacture and disposal (often by incineniian) of chlorinated TM ik compounds. Abo, levels of dioxins and furans in human fray Hne sod breast milk from North Vietnam are the lowest yet measured while levels in South Vietnam ms similar to the ILS* Japan, and 46 Dioxins and Furans L 784147 Europe (Schemer et aL, 1986: R*Jpe ct aL, 1987c: p 233). This riicMM that m d an irfuariai activity, not the burning of wood, is the primary som e of p!* tnd Amu to the eavnoameu. Iii i There is some evidence that the amount of dioxins and fuxans being released into the l environment reached a peak in the mid-1970s a d has declined since. The sediment Icores analyzed by Czoczwa and Hites (1986) showed such a trend. An analysis of breast milk in Sweden also appeared to show this decline; the levels of dioxins and Tuans in combined samples of breast milk have dropped since the study was initiated in 1972 (Notch, 1988). However, studies of dioxins and Tuans in breast milk in Yugoslavia (1981 to 1987) and Japan (1978 to 1984) do not show changes over time (reviewed in Lindsumn, 1988; p 36). i l t Dioxins and Finns 47 784148 GENP 011337 The Health F.fleets at Dtnwmi and F o rm , 1 Animals and Humana T What a n the health'effects oa anlmahT Some general features Dioxins and funuu have some very unusul features with respect to their toxicity to animals. Animals given fatal doses of dioxins and furens do not die immediately; several weeks elapse between the administration of the fatal dose and the death of the animat. Also, many of the acute (short-ienn) effects of less than fatal dares ire temporary. When the animal stops receiving the substance, it recovers from mast of the effects. The rate of recovery varies, and some animals have required more than six months to return to nannal (USEPA, 1985: p 8.48), The toxicity of dioxins and furans is highly variable. They produce a wide spectrum of effects, involving many different organs and body systems, and the affected areas usually vary with the species of animal. The toxicity of different rf and furans v an s widely far a given species of animal, and the toxicity of a given dioxin cr furan varies widely between different species of animals. See Tables 4 and 5 for acutely lethal (causes death quickly) doses of 2.3,7.8-TCDD for a variety of species. Finally, some individuals of a sensitive species (rats or mice, for example) do not die even when given doses as much as 100 tunes greater than the amount that is fatal to the other individuals in the same study. 48 Dioxins and Furans 784149 Table 4. Acutely lethal single doses of 23.7.8-TCDD (LD501 (Emm USEPA. 1985, Table 8.1) Species Guinea Pig Gcader Male Doh microgmnj per kg of body weigh! (ug/kjj) 0j6* Z 1 Guinea Pig Female 15-19 Rat Male 22 Rat Female 45 Monkey Female <70 Rabbit Male 115 Rabbit Female 115 Mouse Male 114-285 Mouse Female >450 Hamster Male 1157-5051 Note: The lethal values above represent doses tha caused the death of 50 percent of the test Such a value is known as an LD50, and is a standard endpoint m a toxicity test. Far aquatic animals, different concentrations of the snhstance in water are used, instead of a dose. The concentration that' cam death of 50 percent of the test animals is called the LC50 (see table below). There are also studies that use different endpoints, such as LD95 or LC95, where 95 percent of the test animals die. Table 5. Lethal exposures to 2-3.7-8-TCDD in water fLCSfll (reviewed in Kenaga and Norm, 1983) Species Coweta frith fa W ater (ug/liter) Q uand Catfish Coho Salmon Guppy 0.0042 (4.2 ppt) 0.0056 (5.6 ppt) 0.1*10 (ppb) D uratka (days) 15 1-3 5 Dioxins and Furans 49 784150 OBn p o u 339 T Generally speaking, all toxic members of itae dioxin and furan families produce similar effects in a given species of animal, and several effects are common to ill mammal that receive s lethal dose of these compounds. Although most studies of the effects of dioxins and furans on laboratory animals have been done using 13,7,8-TCDD, these studies esn be used to predict the toxic effects of other dimim and furans. The chief difference is that a greater dose of other dioxins or furans is necessary to produce the na effects. Many dioxins and furans. are so much less toxic than 2,3,7,8-TCDD that an experiment would require an impracticably large dose to produce lethal effects. Doses_that Produce no observable adverse health effects Long-tenn studies of mice and rats have shown that there are doses of 2J.73-TCDD that produce no observed effects on the animals, even after receiving the substance for two yean. The USEPA estimates the No Observed Advene Effects Level (NOAEL) for toxic effects other than cancer to be approximately 0.001 ug/fcg/day for both mice and rats. They also cited a need for long-term studies using lower doses (USEPA, 1985: p 14.10); some researchers feel that this dose can produce advene reproductive effects (USEPA, 1985: p 14.10), and is therefore a Lowest Observed Advene Effect Level (LOAEL). See Tables 6, 7, and 8 for NOAELs and LOAELs for other species. Also, the toxicity of 2J.7J8-TCDD is at least partially cumulative; a smaller dose than the acutely lethal dose can cause lethal effects if the smaller dose is given for a longer period of time (McConnell, 198ft pp 110-111). l ! r j Table 6. Lowen dam with an observed advene effect (LOAELS (boo USEPA. 1985, Tables 8 4 , 8-5) Spcdes Dose Deration Effects Rat 0j01 ugftgfday 2 yesti Liver damage Mouse 0.001 ugftg/dsy 1 year S eres! Guinea Pig 0.006 ug/kg/dxy 8 weeks S croll (For the studies above, ihe animal received 2J.73-TCDD in their food or were force-fed 2J.7J-TCDD once per week in a medium such a core off.) 50 Dioxins and Furans GENP 011340 784151 Table 7. Lowest concentration with observed adverse efFaet rt.OAPL'i Spedes CoGcentntioa [a Water ug/liter (ppb) Duration days Nrethera Pike (eggs)' 0.0001 (0.1 ppt) 4 Rainbow Treat* 0.0001 (0.1 ppt) 4 Fathead Minnows" 0.0017 (1.7 ppt) 28 * (Helder, 1982) (W. Adams, et aL, 1986) EfTed Lowered Suxvrvil L ow ed Survival Lowoed Survival Table-8. Highest concentration with no observed adv* r f f " - * fWOAPT.^ (reviewed in Kenaga and Noiris, 1983) Spedes CoBcentratiM ia Water ug/luer (ppb) Coho Salmon 0.00056 (0.56 ppt) Rainbow Trout 0.0001 (0.1 ppt) Mosquito larvae (Aedes aegvmil 0.2 Daphnia (Panhnia mama* 1.33 Alga fQedogonium cardiacum) 1J3 Duratkm days 4 4 17 32 32 The short-term health-effects on animals All earnmats given an acutely lethal dose of a dioxin or ftnan offer ftoo wising (toaiag weight), and it is sometimes the only effect leading to d esk The animals simply waste away. This ocea n primarily because the *<*** do not eat eaough food to maintain their weight. Apparently, the animals' internal weight "setting* is lowoed below nomal. and so the animals do not eat enough food. Howevo, then ta evidence that this redaction of nourishment is not entirely responsible for the weight loo. Resemhen who fare^fed the snhnslt could prevent some of the weight loss, but not all, red the ta ils died anyway (Gasiewica et aL, 1980). Dioxins and Furans 51 784152 GENP 011341 T Hie thymus is affected in all mammail exposed to a toxic dose, aod die liver is affcctod in most mammals. The thymus, and to a lesser extent the spleen and lymph nodes, typically suffer damage and a reduction in size, while the liver typically stiffen damage aod an increase in size. In rodents, liver damage is suspected to be a principle cause of death. Skin disonkn have occurred in rabbits, monkeys, cattle, and hairy mice. The effects include severe acne, thickening of the eyelid, and abnormal growth or loss of hair, fingernails, toenails, or hooves. Dioxins and furans have also affected the cardiovascular system, gastrointestinal aod urinary tracts, spleen, bone marrow, and gallbladder of animals. For reviews of the above health effects, see Gupta et aL, 1973: Poland and Knutson, 1982; USEPA. 1983. Cancers 2J.7.8-TCDD is a carcinogen in mice and rats, when fed to the animal or applied to the skin. Two-year studies at Dow Chemical Corporation (Kociba et aL, 1978) and at the National Cancer Institute (NTP, 1980s; 1980b) found increased cancers of sevenl types, resulting, from chronic Gong-term) doses as low as OjOI ug/kg/day. Rats fed this dose for two yeas had, at the end of the Dow study, 1700 ppc 23,73-TCDD in their faL The rats fed this dose also suffered increased morality, decreased weight gain, and increased excretion of porphyrins (a pigment produced by the liver which indie [Wer damage). Rats fed 0.001 ug/kg/day suffered no health effects of consequence, and had 540 ppt 2J.7.8-TCDD in their body fid at the end of the study. Long-term studies have zUo been conducted using a mixttao of two hexa-CDDs, both containing chlorine atoms in the 2J,7^od 8 (NTP, 1980c; 1980d. The mixnac caused liver tuman in both mice and n tt when administered orally in dtHes of Z5-5J0 uffkgfweek (far female rats), 3.0 ug/kg/wcek (far male mice rod rata), and IOjO ug/kg/week (for female mice), but not at lower dares. The mixture wm not carcinogenic when 0,1 ug was applied to the skin three times per week. Many researchers have concluded that 2J.7.8-TCDD is a promoting, rather than an iniriremg. carcinogen. A promoter provides a favorable environment far tumor growth, while s i 32 Dioxins and Roans GENP 011342 k 784153 initiator produces a change in DNA that causes tumorous growth. Tumor -a 1 reversible and is not inherited, while tumor inidation is not reversible arel is on through cell diviaiaa (Rarcncnbncb a al, 1986). Pitot et al (1980) used dietfaylmtresgmiK to to turnon in mice, and found that 2^,7,8-TCDD promoced the growth of the in itia l turnon. Abo, Kouri et al (1978) used 3-methyl<chol8ntfarens 10 initiate subcutaneous tnmon in mice, and found that 2J.7.8-TCDD promoted the growth of these tumors. Reproductive effects Dioxins and fuians appear to be especially toxic to embryos and fetuses, and the reproductive system of adult animals appears to be especially sensitive as welL Mice and rats have produced litters with abnormally high rates of birth defeas such as cleft palates, extra ribs, and deformed liven and kidneys, after receiving doses of 2,3,7,8-TCDD as low as 0.01 ug/kg/day, or a single dose of 1 ug/kg (reviewed in USEPA, 1983: pp 9.1-23). Reproductive effects such as smaller litters, lower birth weights, and premature abortions have been reported in monkeys and ferrets, as well as in rats and mice, that were administered 2J.73-TCDD, When 23,7,8-TCDD was fed continuously to three generations of labomory rets, reproduction was impaired by a dose of 0.01 ug/kg/day, bat not 0.001 ug/kg/day (reviewed in USEPA. 1985: p D.1). Female Rhesus monkeys suffered reduced fertility after being fed 0.0015 ug/kg/day 2J.7.8-TCDD (reviewed in USEPA, 1985: p D.1). These effects have only been observed when the embryo or mother was exposed to 2J.7.8-TCDD, and appear to be the result of direct exposure or transfer of the toxin from mother to embryo across the placenta. Birds defeas have not been isaociffl with exposure only to the father, nor has reproduction been reduced when only the father was exposed to 2J.73-TCDD (reviewed in Kanuin and Ma&nnure. 1985; reviewed in Silbagdd and Maoism, 1987: p 137). However, 2J.73-TCDD can reduce the weight of testes, lower levels of testosterone, and impair the developmea of sperm, in rodents, monkeys, and chickens (reviewed in Poland and Knutson, 1982: p 524). iI Dioxins tnd Furans S3 784154 Mutagenic effects An important question about any toxic substance is whether it causa changes a the DNA of exposed organisms, because such changes can then cause cellular mutation. Such a ijtxaancg is called a mutagen. A small number of eariy studies found 2^,73-TCDD a be a weak mutagen, while many subsequent studies have detected no evidence of mutagenicity. Mott researchers have concluded that 2 ^f7$-TCDD is not a mutagen (reviewed in Hay, 1984; reviewed in Poland and Knutson, 1982: p 525). Immune effects 2,3,7,8-TCDD has been shown to inhibit the immune system of mice, rats, and guinea pigs, at doses much below the fatal level. The thymus, spleen, and bone marrow have all been shown to suffer loss of tissue, and the enzyme unmine system and oell immune system which normally react to a potentially toxic substance are inhibited (reviewed in Poland and Knutson,' 1982; p 522; reviewed in USEPA. 1985: pp 8J15*86). Similar responses have been observed with 2J.73-TCDF, at doses thirty Limes higher than Gar 2J,7$-TCDD. The effects of the 2J.7.8-TCDF disappeared six weeks after dosing ended (Veccfai et aL, 1983). EflscB-fln-hlflaLcpnsiiiucnB 2J.7.8-TCDD and 2J.7.S-TCDF have been shown to affect a variety of constituents in the blood of test animals. 23,7,8-TCDD has been shown to reduce the number of red and white blood ceils (Kociba et aL, 1978), change die level of blood lipids such as triglycerides and esters, and change the levels of thyroid hermotes such as thyroxine and thyrotropin (reviewed in Poland and Knutson, 1982: pp 526*529). Blood levels of progesterone and estrogen decreased in Rhesus monkeys fed 2J.73-TCDO, and blood levels of itoiMiwj fa nw (reviewed in Peterson et aL, 1984). 23,7>7CDF h a been shown to m etre the levd of serum globulin in mice, and decrease serum cholesterol aid seram albcania in monkeys (Moore et aL. 1979). 54 Dioxins and Furans 784155 A n dioxins and (brans hazardous to organisms in the environment? Very little is known about the impact of dioxins end furans on organisms in the environment, especially at low levels. Many animals died after being exposed to relatively high levels of dioxins and furans, as a result of the accidental contamination of areas surrounding Seveso, Italy, and Times Beach, Missouri (reviewed in Reggiani, 1980: pp 318, 325). It was reported that six months after the Seveso accident, normal populations of wild and domestic animals were present in the contaminated area, and appeared to be in good health (Homberger ct al,, 1983, cited in OME, 1985: p 3.92). Fourteen rabbits from the zone of highest contamination were collected, sacrificed, and examined, three months after the accident. All had more than 300 ppb 2J.7.8-TCDD in their livers, and 5 showed evidence of liver damage. Blood constituents were normal in all 14 rabbits, and no other health problems were observed (Abbiuzzi et aL, 1977, cited in OME, 1985: p 3.92). 2^,7,8-TCDD is also suspected of causing reproductive failure in fish-eating birds of Lake Erie and Lake Ontario (Gilbertson and Fox, 1983). The reproductive failure was primarily the result of unusually high embryo and chick mortality.' A study of several gull colonies found that the embryos and chicks were suffering from chide edema disease and hepatic porphyria, which are both indicators of poisoning by dioxins, furans, and related compounds such as PCBs. Relatively high levels of 2.3,7,8-TCDD were later detected in gulls from Lakes Ontario and Erie (Norstrom ct aL, 1982). Other contaminants such as PCBs, DDT; and hexachlorobenzene were also detected in relatively high levels in these birds, and may have been responsible for these health effects. Several environmental studies of organisms exposed to 2 J ,7,8-TCDD and other dioxins and furans have found little or no health effects. A 15-year study of beachmtce at a highly contaminated site in Florida (Young et aL, 1987) found that the 1 ppb levels of 2^,7,8-TCDD in the soil had no observable effect on the birthrate of the mice, and enlarged liven was the only observed effect Also, NCASI sponsored a five-month study of plants and animals exposed to dioxins and furans from paper sludge spread on a pine plantation (NCASI, 1987b). The 10 Dioxins and Furans 55 784156 GENP o i i 3 4 5 li ppt 2^,7,8-TCDD and 100 ppt 2J.7.8-TCDF in soil hid no obaovabto effect* on the health and reproduction of the organisms studied. More studies of (he environmental effects of dioxins and Cuians are needed. What are the pharmacokinetics of dioxins and furaus? In order to understand why many dioxins and fmans accumulate and persist in animals and humans exposed to them, why the p**** vary with the type of dioxin or furan, and how these characteristics relate to the varying toxicity of dioxins and bums, it is helpful to know something about the pharmacokinetics of dioxins and furans (their absorption, distribution, metabolism, accumulation, and elimination, in animal. and humans). Dioxins and furans arc intermediate in their affinity for fat (this is known as lipidsolubility). They are soluble enough to be readily absorbed through the walla of the digestive tract, but not so lipid-soluble that, once absorbed, they are found only in the adipose (fatty) tissues of the body. They are also found in the liver and in other organs. Adipose tissue is the body's storage depot, and substances there are 'in limbo". They are not interacting with the mechanisms that cause effects (toxic or otherwise), nor with the mechanisms that metabolize the substances. Therefore, the intermediate lipid-solubility of dioxins and furans makes it possible for them to penist in the body and be available to the mectanisms that cause toxic effects (Matthews and Bimbaum, 1983). Studies with rodents show that 2J,7$-TCDD is absorbed primarily through the gastrointestinal tract, and to a much lessre extent through the skin aid lungs. When 2J.7.8- TCDD was administered orally in food or in com oil, bom 30-90% of the amount was then absorbed through the gastrointestinal tract (reviewed in USHPA, 1983: p 72). When applied to the skin in a solvent such as methanol, from 1-10% was absorbed. The absorbed 2J.7.8-TCDD is distributed rapidly to many pans of the body, but the major sites of storage are almost entirely the liver and the Catty tissues (reviewed m Casiewicz et aL, 1983). The sites of storage vary somewhat with the species. 2J.7.8-TCDD is stored in its original bam, not as a changed 56 Dioxins and Furans A GENP 011346 784157 wfg f e *^ .T product of metabolism. Apparently, metabolites sre exacted once they tic fanned It appears thm the absorption of dioxins and funns decreases ts the number of chwtmr 00 ^*^* (reviewed in Matthews and Bimbaum, 1983). The metabolism of 23.73-TCDD has been studied primarily in rodents. Metabolism is affected by the number and position of chlorine atoms (reviewed in Matthews and Bimbaum, 1983). The critical factor for metabolism is the presence of two adjacent unsatotitmed carbon atoms (not attached to a chlorine or other atom). When chlorines fill the 23,7, and 8 positions, no adjacent unsubstituted carbon atoms are left on the dioxin or funn molecule, and very little metabolism takes place. A year after people in Japan ingested a number o f different types of funns that were accidentally present in rice oil (known as the "Yusbo" incident), no furans with adjacent unsubstituted carbon atoms remained in their tissues. Apparently, these types had been metabolized and excreted (Rappe cl aL, 1979, cited in Matthews and Bimbaum, 1983). Furans with the 23,7, and 8 positions filled were still present in the tissues. In the general population, the only dioxins and furans found in people are those that are 23.73-substituted (Ryan, 1986), The accumulation of dioxins and furans is the product of absorption aid metabolism, and varies with the type of dioxin or furen. For instance, studies with carp and rodents have shown that they preferentially absorb those types with the 23,7,and 8 positions filled, and they absorb a greater proportion of the available dioxin or furan as the number of chlorines decreases (Kuehl a aL, 1986; 1987a; 1987b; Opperttuizen et aL, 1986; van den Bog et aL 1986). Although relatively small amounts of hepa* and octa-CDDs/CDFs are aborted, these smalto amounts accumulate and persist in the body far longer periods of time. 23,73-TCDD has been cJimimtrd slowly from the bodies of exposed animals; the half-life varies from 10 days to approximately one yew, depending on the species. In humans, 23.73-TCDD appears to be eliminated quite slowly. Based on the ram of disappearance of one billionth of a gram of self-ingested 23,73-TCDD, Poiger and. Schlatter (1986) estimate a half-life of about six yeas. They also found that (be dioxin was disribuied quickly in the blood and stared almost entirely in the Catty tissues. A half-life of atom seven years was Dioxins and Furans 37 784158 9t by researchers from the CDC, baaed oa measurements of 2J.7.8-TCDD in the blood of Ranch Hand personnel (Pirkle et aL, died in CDC 1988). Recent work with pharmacokinetic models suggests that the half-life of 2J.7.8-7CDD is inversely related to its concentration in human laity tissue (Kissel and Robarge, 1988). They predict that the half-life is 4.4 yean when 2,3.7,8-TCDD is present in Catty tissue at 100 ppt. but increases to 20 yean as the tissue concentration approaches 10 ppt (a typical level in a person from an industrial country). The rate of elimination of dioxins and Tuans increases as the number of chlorines decreases (reviewed in Matthews and Bimbaum, 1983; Kuehl et aL, 1987b), and studies with rodents and Fish have shown that Tuans are eliminated more quickly than their counterpart dioxins (van den Berg et aL, 1983; Kuehl a aL, 1987b). Apporendy, 23,73-TCDD must be metabolized io different compounds in order to be excreted in the urine and bile (reviewed in Olson a aL, 1983: p 97). However, uiunetabolized 2J3.73-TCDD can be excreted in the feces (USEPA, 1985: p 7.20) and in breast milk (Moore et aL, 1976; van den Berg et aL, 1986). Studies of people exposed to Tuans in the Yusbo incident showed that the furans were also stored in the fat tissue and in the liver, and were metabolized at a slightly Caster rate than that found for 2.3,7,8-TCDD, above (reviewed in Reggiani, 1983: pp 59-61). It has also been shown that nursing women excrete both dioxins and furans in their breast milk, and there is some evidence that nursing can reduce the amounts of these compounds in the body (Noren, 1988; Ogaki et aL, 1987, reviewed in Undstnxn, 1988: p 34), In some cases, the toxicity of a dioxin or A nn has been related to the rate of metabolism. For instance, the toxicity of 2J,7$-TCDF to different species was found to be inversely proportional to the rate of metabolism (reviewed in Matthews and Bimbaum, 1983). Also, a study of 2j8-di-CDD in goldfish fo w l that, when the metabolism of this dioxin was prevented, it was l/60th as toxic as 2 Jt73*TCDD (Sijm and Opperfnrizen, 1988). Normally, 23-di-CDD is metabolized too quickly to accumulate, and is almost nontoxic. Metabolism alone cannot explain the varying toxidties of Hinrira and furans, however. For in, rats metabolize 2J.7.8-TCDD about three times (aster than do guinea pigs, yet the LD50 for the rat 58 Dioxins and Furans 784159 I 0 ,r is 3000 to 5000 times greater than that for the guinea pig (reviewed in Poland and Knutson, 1982: p 321). Also, octa-CDD is metabolized very slowly (Bimbaum and Couttne, 1988), yet is very much less toxic than other dioxins and fuians with chlorines in the 23.73 positions. What are the effects of dioxins and fu ru e oa human health? Our understanding of the effects of dioxins and furans on humans is not based on controlled studies such as were done with animals. Instead, it is based on studies of people who were inadvertently exposed to these substances, as a result of an accident, their occupation, or other circumstances. This presents two major difficulties: 1) we cannot control and often do not know the level of exposure (the dose); 2) people have almost never been exposed to these substances alone: the dioxins and furans have been mixed with other substances (PCBs, PBBs, chlorophenols, chlorophenol-based herbicides, and so on). These other substances have been shown to cause some of the same health effects as dioxins and fuians, but only when people have been exposed to much larger amounts. An impo*rtant difference between the toxicity of dioxins and furans and these other substances is the comparatively small amounts of dioxins and furans that can cause serious health effects. In most cases, the level of exposure to the other substances has been too low to cause such effects. The health effects of toxic substances can be divided into two major groups: 1) acute (short-term) effects, which occur soon after expos and quickly subside; 2) chronic (long-tom) effects, which can occur anytime during the life of the person and can be persistent. Our knowledge of the acute effects of dioxins and furans is based on studies of people who were exposed to relatively large amounts, usually as a result of an industrial accident Our knowledge of the chronic effects of dioxins and furans is based on long-term studies of these same groups of people, or studies of people exposed to relatively small amounts for a long period of time. With these long-term studies, it is m m difficult to remove the confounding effects of exposure to organic chemicals other than dioxins. Dioxins and Furans 39 1 i 784160 GENP 011349 The short-term health effects on humana Dioxin and fumni have caused s host of reported acute effects on people who wem exposed to relatively high levels. Ute reported clinical symptoms (directly observable or felt by the patient) include nausea and vomiting, headaches, irritation of the eyes, skin, and gastrointestinal tract, and a general feeling of not being wdL Pain, especially in the limbs, has been reponed as persisting far months, as has an enlarged and tender liver, and irritability and nervousness. There is no documented case of a person dying because of exposure to dioxins and furans. In addition to the clinical symptoms, there are reported effects detectable by laboratory tests or study. They include liver damage, elevated levels of constituents of the blood such as triglycerides and lipids, and damage to the nerve fibers. Although most people recover quickly from the acute effects of dioxins and furans, there are repairs that some of these effects have lasted for months or yearn. Fr reviews of the acute hunun health effects of dioxins and furans see USEPA (1985: pp 8.60-8.65); Hay (1982); Reggiani (1982). The long-term health effects on humans The most common chronic effect of exposure to dioxins and furans is severe and persistent acne, called chlotacne, which can occur in many parts of the body. Excessive body hair and pigmentation, and elevated levels of blood constituents such as triglycerides, cholesterol, liver enzymes, and porphyrins have also been reported several yean after the high expouae. Nerve disordea have been reported, including problems with or Ion rtf some vision, hearing, taste, and smell. Also, general weakness and a loss of sexual drive has been reported to occur for some yean after high exposure. Tho reported symptoms rod effects at exposure to dioxins and furans have been inconsistent, with the exception of chioracno. Howevg , in most cases a enlarged and/or damaged liver and neuromuscular symptoms have also been reported. For reviews of the chronic human health effects of dioxins and furans, see USEPA (1983: pp 8.65-8.69); Hay (1982); Reggiani (1982), 60 Dioxins and Furans GENP 011350 M 784161 r Cancers A few epidemiologic studies have found an association between cancers and occupational exposure to dioxins and fisans. Ibe studies that an generally considered to offer the best evidence were earned out in Sweden. Abocnnally high levels of a ra e type of cancer, called soft-tissue sarcoma, were found in men who were exposed to ddorophenols and chlorophenol-based herbicides (reviewed in Hardell, 1983). Ib e Swedish studies have been criticized for unreliable diagnosis of soft-tissue sarcoma (Hajdu, 1984), and for relying on the waiters' memory of their exposure to the substances (Cook, 1983). In general, the diagnosis and classification of this rare type of cancer is difficult, and relying on memory f a an appraisal of a subject's health is an admitted weakness. Similar studies have since been conducted in several countries, and no such association has been found (reviewed in USEPA, 1985: 11.64-91). Several of these saidies are not considered sensitive enough to detect the small numbers of a cancer as rare as soft-tissue sarcoma (reviewed in USEPA, 1985: 11.64-91). After the Swedish results were published, a review of the medical history of men in the VS. who were occupationally exposed to chlorophenol-based chemical products showed an abnormally high number (seven cases) of soft-tissue sarcomas (Honchar and Halperin, 1981). The authors of the U.S. review subsequently helped to reexamine the data, and they determined that only two of the seven workers were bah 1) exposed to dioxin- and furan-contaminated products and 2) correctly diagnosed as having soft-tissue sarcoma (Fingedun et a t, 1984). Nevertheless, two cases still represents a significantly higher number of soft-tissue sarcomas f a this group (USEPA, 1985: p 11.91). A similar study in Sweden found no association between rates of soft-tissue sarcoma and exposure to pheaaxy-acid herbicides, among 350,000 Swedish agricultural or forestry workers, when compared to 1.7 million Swedish workers in other industries (WOdund and Holm, 1986, died in Fishbein, 1987). In their 1985 Health Assessment f a dioxins, the USEPA stated that the Swedish studies offer 'limited" evidence f a the caidnogemtiiy of dioxin-contaminated chlorophenols and Dioxins and Furans 61 ' 784162 OBNP01135, chlorinated phcnoxyacctic herbicides (such as 2,4,5-T), but "inadequate* evidence for the carcinogenicity of 2J.73-TCDD alone (USEPA, 1983: p 11.138-140). In addition tn the association between exposure to dioxin- and fiuan-contaminated products and soft-tissue sarcomas, a few researchers have reported finding such an association with nasal cancer (reviewed in HarddU 1983), stomach cancer (reviewed in USEPA. 1983: pp 98-107), and cancer of circulating cells (reviewed in USEPA, 1985: pp 92-98; reviewed in Hardcll, 1983). Similar.studies of workers exposed tn dioxin- and furan-contaminared products have not found elevated levels of cancers (reviewed in Reggiani, 1983; p 483). The USEPA Health Assessment considered the available evidence far these other cancers to be inadequate, and this is on opinion shared by a majority of researchers. The great majority of researchers in the field of toxicology or epidemiology feel that the numerous studies of the human carcinogenicity of dioxins and forms have provided inadequate evidence that they cause cancer in humans. Based on the epidemiological evidence and the knowledge that some dioxins and furans are proven carcinogens in animal, dioxins and furans are suspected human carcinogens. Abortions, birth defects A small number of researchers have found an association between exposure to 2,3,7,8- TCDD-conlaminaled products and abnormally'high levels of abortions or birth defects (reviewed in USEPA, 1985: pp 9.23-36; reviewed in Hatch, 1984; Albaneae, 1988). Children of mothers who consumed rice oil contaminated with PCBs and firm s (the Yusho incident) were bora with dark pigmentation and deformed fingernails (reviewed in Kuraoune, 1980: p 299). Some of these babies also suffered from slowed growth, and chlorate. U has generally been concluded tits furans were responsible far these effects (Kuniu.et if, 1984). Other researchers conducting simitar studies have found no such association (reviewed in USEPA, 1983: pp 9.23-36; reviewed in Hatch, 1984; Mastraiacovo et aL, 1988). Many of these studies have been largely discounted because of weaknesses in the methodology (USEPA, 1983: pp 913-36). There is thus far inconclusive evidence of an association between and furans and abortions, and an association with birth defects was detected only in the rare circumstance 62 Dioxins and Furans GENP 011352 784163 1 where the mother was exposed to extremely Urge amounts while pregnant (the Yusho ingM^n) If these substances are capable of causing socb effects cn humans, then dtfaer the level of expoetae must be extremely high, or they cause tare types of birth defects Act researchers have not been able to detect in significant numbers. Again, this is an area where further investigation is nr Immmg-sffwa A few researchers have reported an association between long* term exposure to 2,3,7,8TCDD and an impaired immune system (reviewed in Hay, 1982). Other long-term studies have found no effects on the immune system (Albanese, 1988; Fan et al., 1982). A study of people exposed to 2,3.7,8-TCDD in Missouri found evidence of an abnormal cellular immune system (Stehr-Green et aL, 1987). However, the effects did not result in increased illness. Also, the authors noted that these effects may be pan of a normal response to a toxin in the body, i.e., they could be considered indicators of exposure and not signs of disease. Conclusions on health effects The long-term health effects of these compounds have been intensely investigated, making them among the most-studied substances with respect to their -effect on animal and human health. Dioxins and furans cause mortality snd/or cancer in many animals, but there is no conclusive evidence that they cause cancer or any other life-threatening health problem in humans. No documented human death has occurred because of an exposure to dioxins or furans. People have been exposed to relatively large amounts of dioxins and furans (1 ug or more) during industrial accidents, and other incidents of accidental contaminaaon (Yusho, Times Beach). The symptoms of these high-level exposures include dirancsi. heartaches, liver damage, leg pains, and reduced sex drive. These symptoms, though serious, have typically subsided with time. An exposure to these amounts can also cause severe acne, called chioracne, which in some cases has persisted for drearies With the exception of chioracne, most Dioxins and Furans 63 784164 GENP 011353 researchers have found no serious, long-term health problems associated with exposure to dioxins, even at the highest reported levels. However, some studies have found an aaoriarion between long-term diseases and exposure to dioxins and furans. Several Swedish studies hive shown in association between a person's exposure to 2J,73-TCDD-comaining heririeides and the incidence of a tare form of cancer. Other and subsequent studies have not coofmned this association, and the Swedish studies have been criticized on several grounds. Nevertheless, because they are very potent toxins and carcinogens in laboratory animals, the U.S. Environmental Protection Agency, Centers for Disease Control, Food and Drag Administration, and other groups, have issued guidelines for human exposure to dioxins and furans, based on the results of animal studies in the laboratory (see "How do government agencies arrive at acceptable human exposure to dioxins and furans?*. page 65. Haw da dioxins and furans cause the health effects that they do? We don't know yet why dioxins and furans cause the health effects that they do. But because these substances a(Tea so many systems of the body, it is expected that the mechanism of toxicity involves metabolism at the cellular level. For example, it has been proposed that many of the toxic effects of dioxins and furans are similar to vitamin A deficiency (Hakanssan et il, 1988). Some of the toxic effects of and furans (and other fatngwfnv* aryl hydrocarbons such as PCBs and PBBs) have been linked with the cellular machinery that makes and releases certain enzymes (Poland et aL, 1979). Also, 2J.73-TCDD h a been linked with clunges in the outer membrane of the cell (reviewed in Matsumma, 1985). It is not likely, however, that these changes in the cell n directly responsible for the toxic effects. Tr****. it appears that the toxic effects are somehow mediated by these enzyme systems and the cell membrane. 64 Dioxins and Furans GENP 011354 784165 Rerouting Dkaltts Md Furan How do government agenda arrive at acceptable expoaare to dloxfas and furana? Government agencies from many different countries have detennined maximum acceptable doses of 23,7,8-TCDD for humans, which are then used to regulate practices that expose people to dioxins and furans. These acceptable doses (also called tolerable, allowable, and virtually safe) vary from country to country, and can vary from agency to agency within a country (see Figure 4, following page). This variation is primarily the result of differing interpretation of the same experimental animal data, and to a lesser extent the choice of different data. In order to understand how this comes about, a brief summary of how an agency determines an acceptable dose is in Oder. First, suitable data must be chosen. The results of animal laboratory studies are relied upon most heavily and are often the only data considered. This is because human studies (epidemiological studies) are after-the-fact investigations of uncontrolled exposure, making it extremely difficult to confidently correlate a given dose of the substance with the observed health effects. Animal laboratory studies allow several controlled doses, including lethal doses, to be used, and allow the researchers to examine the health effects ova- most or all of the I lifetime of the animal. I I I Dumas and Furans 65 i \ i 784166 i GENP 011355 W&L. S ? . Ftgme 4. Virtually safe lifetime daily doses of 2J.7.8-TCDD fawn various agencies am) countries. from Figure 1 in USEPA, 1988c: p 4, A femsognm is coo quarfrilliondi of a gum (1 x Iff" grems) 66 Dioxins sod Furens ^ENP 011356 784167 Tbe effects of different doses on long-torn health aspects such as cancer, birth defects, and changes in the immune system are typically used by regulators, >*** they have very serious consquences. In the United Slates and Canada, for example, data Cron long-tenn studies of cancer in rats have been used to estimate an acceptable dose of 2J.7.8-TCDD. Rats were chosen as subjects became they are physiologically similar to humans, reliable strains of rata have been developed for use in such studies, and large numbers of tbe mil can be used for the experiment Regulators must then extrapolate an acceptable dose for humans from the chosen data. It Is this extrapolation that accounts for most of the variation in acceptable doses. Tbe extrapolation can be done using two major methods: 1) applying safety factors to the largest dose that could be correlated with no observed advene effect (the NOAEL); 2) using the various doses and their correlated adverse effects to extrapolate a dose that would be theoretically associated with an acceptably small risk of causing the effect. For example, the USEPA considers a risk of one tumor in one millioa people during an average lifetime of 70 yens to be an acceptably small risk. A safety factor (method 1) is used when tbe regulators decide that there is a threshold dose below which there is only a remote risk that the health effect will occur. Tbe safety factor is then applied to allow for individuals that are more sensitive to the toxic effects than the average, and to allow for the possible difference between the test species and humans. Safety factnra of from 10 to 1000 have been applied, depending on the confidence the regulators have in the available data. The dose extrapolation (method 2) is used when the regulatora deride that any dose, no matter how small, tnaeares the risk of tbe health effect Because the aim of this method is to quantify the risk and then choose an acceptable level of risk, such an appnach is called quantitative risk assessment There are many diffrera mathematical models dut can be used to extrapolate quantitative risks from a range of (k m , and the extrapolated degrees of risk can vary considerably, depending on the model chosen. 1 Dioxins and Furans 67 784168 GENP 011357  $ The f hrat i outlined above account for the range of acceptable daily lifetime doses of 13,73-TCDD as presented in Figure 4. The lowest (USEPA) and highest (Ontario Ministry of the Environment) dore-s in that table were derived from the same Eortg*tenn studies of n ts by Kocibn et al (1978). The USEPA also used a similar study by the National Cancer Institute (NTP, 1980a); the Ontario Ministry of the Environment also used a similar study by Murray et aL, (1979). Because the USEPA feels that there is no threshold below which 2J.7.8-7CDD does not cause an increased risk of cancer, they used a dose-extrapolation model to calculate the acceptable daily dose. The model they used to arrive at the present virtually safe dose is the most conservative of the five models they tested; it extrapolates a greater risk than do the other models at low doses. The Ontario regulators recognize 2J.7.8-TCDD as a promoting rather than an initiating carcinogen, and therefore feel that there is a threshold dose below which Z3.7.S-TCDD probably does not increase the risk of cancer. They applied a safety factor of 100 to the dose that they felt represented the NOAEL in these studies, to calculate an acceptable daily dose. Thus, we have two very different interpretations of essentially the same data. The USEPA's recently proposed virtually safe dose is greater because it reflects (he median virtually safe dose from the different models, rather than the most conservative. As has been pointed out by Lave (1983), when the mechanism of action of a toxin is unknown, all applicable models are equally valid and should be used to derive a range of risk *<*"* No single model should be chosen, because undue emphasis is then placed ao ana estimate in what is a large range of equally relevant estimates. At the same time, regulator should make couovative assumptions. Then, as their knowledge shore the toxin increases and they replace their conservative assumptions with more accurate ones, the risks should decrease. This provides an incentive far industry to conduct research on toxic substances; Because of lack of information about dioxins and fanes. the USEPA and other regulatory agencies have made very conservative assumptions when the health risks of these compounds. Many researchera have argued that the assumptions are overiy 68 Dioxins and Furans GENP 01-1358 784169 i*** conservalive, and thess argumenu have grown more persuasive as our knowledge of ftiniin and furans has increased. For example, Paustenbach et al (1986) critically the assumptions used by the CDC and USEPA to determine the risk posed by 23,7,8-TCDD In soil. Their analysis indicates that the CDC and USEPA significantly overestimated the risk of 23.7,8- TCDD in soil Also, although the CDC made it clear that their risk assessment was 1) specific to the residential area in Times Beach, Missouri and 2) not applicable for industrial sites, the USEPA subsequently adopted their guideline of 1 ppb 23,7,8-TCDD in soil to determine the need for cleanup at industrial sites, where the level of exposure would be much lower. What has been done about dioxins' and furans? The manufacture and use of 2,43-T and the related herbicide Silvex in the U.S. was restricted in 1970, and prohibited in 1984. The manufacture and use of chloropbenols has been greatly reduced. No chloropbenols with four or fewer chlorines are being produced in the U.S. (pers. comm., John Robinson, Vulcan Chemicals), and hexachlorophene is MX being produced because of the laeje of 2,43-trichlorophenol (USEPA, 1986: p 3*16). The USEPA requires that pentacblorophenol produced in the U.S. must now average no more than 2 ppm hexa-CDDs, and cannot have more than 4 ppm hexa-CDDs (Vulcan Chemicals, 1988). Approximately half of the hexa-CDDs present are 23,73-subsututed (pen. comm.. John Wilkinson, Vulcan Chemicals). The USEPA intends to cancel most non-wood uses of pentadtlaropbenol (USEPA, 1987b: p. 21413). Wastes from the manufacture of tri-, te n -, aid pcntachtoropbenols, and from the manufacture of te n -, pent-, and hexachlorobenzene under alkaline condition, were designated as acutely hazardous by the USEPA in 1934. The regulations also apply to discarded, unused chloropbenols or products containing them, to products made with equipment previously used to manufacture the substances above (except pentacbkxpphenols), and to soil that has been contaminated by these substances. The manufacturers or owners of such wastes are required to notify the USEPA. These wastes cannot be placed in a landfill if they contain more than 1 ppb Dioxins and Furans 69 784170 GENP 011359 of certain and funms congeners (USEPA, 198& p 23), and if incincraicd. 993999% af the containinaiioo must be removed (USEPA, 198&p 23). The USEPA has proposed that wasewmen and drippings, from wood-preserving facilities and sawmills that use chlorophenotic solutions, or that toe equipnea formerly used far stsh solutions, be tegulaied as hazardous wastes (USEPA, 1988a). Also, 23.7J8-TCDD is now listed under the Clean Water Act as a compound which the USEPA must control in industrial effluents (pen. comm., USEPA). PCBs are no longer produced in the U.S., and any new use of them is strictly controlled and must be extremely well justified. A gradual phase-out of PCB-containing equipment is taking place. Transformen that contain fluid with more than 500 ppm PCBs are now prohibited where they can contaminate food or feed, must be registered and inspected, and leaks must be repaired within 48 hours. Capacitors with more than 500 ppm PCBs are also inhibited from areas where they might contaminate food or feed, and large capeciton had to be placed in enclosures by November 1988. The disposal of PCBs is also highly restricted. Fluid contaminated with m an than 500 ppm PCBs must be incinerated with a removal efficiency of 99.9999%, and fluid contaminated with more than 50 ppm cannot be placed in a landfHL It is a violation to store PCBs for more than one year before disposal (pen. comm., USEPA). Hie USEPA has published lists of chemical products that may be contaminated with chlorinated or brominated dioxins and furma (USEPA, 1987b). Msaufrctiiere or importers of the chemical products on .these lists must test far and report m dm USEPA on the presence of dioxins and funms in these products. The USEPA also published a list of precursor products, which are not contaminated themselves but may produce dioxins or forms if they are used to manufsemre other inducts. Manufacturers or importers of protluuu made with there precunon must notify USEPA of that fret (USEPA, 1987b). The USEPA conducted a nationwide survey iu order lo determine the extent of contamination by 2J.73-7CDD. The most severely contaminated sites woe assigned to the Stqierfrnd List (most won already on the list because of the prejmeo of other toxic substances). 70 Dioxins and Furans L. G E N P 011360 784171 W ten tte USEPA found idttively high levels of 2JJJB-TCDD in fish, advisories were issued to uh amsmnptioo. Also, a program was put in place far cleaning up the many contaminated sites in Missouri, and many of the sites have since been cleaned up. Dioxins and Futans 71 784172 GENP011361 mt <& Conclusions and RccoameadaUo We need to know mare about the toxicity, distribrioo, and behavior of chlorinated djffmw and furam other than 2J.73-TCDD, espedally those that are found in relatively large amounts in the environment. For instance; current research indicates th s the common oca-CDD is biologically active, not non-toxic as has been believed (Couture et a t 1988). Based on the many studies already published, dioxins and fuians do not appear to be a hazard to our health when we are exposed to the low levels typically present in the environment. The epidemiological evidence indicates that dioxins and fain s do not cause cancer, immune effects, or other serious, long-term health effects on humans, even at very high doses. Some groups of people, such as workers who are exposed occupreiooally to greater amounts over a long time, and breast-fed babies, need special attention. We should continue to monitor the health of those persons who have been exposed to large amounts of these compounds, or who are exposed to smaller amounts far a long time. This will enable us to identify any long-term health effects not already recognized. We also need to determine the mechanism of action. Such an understanding would not only have preventive or therapeutic value, but is also critical far accurate assessments of the risks these compounds pose. Brcatur. of their demonstrated toxicity to laboratory animals, plus their distribution and persiitrnce, some <*** and furans are a pr*rrigi hazad organism in the environment. There is a great need f a more study in this are i We need to know what are unacceptably harmful levels f a the various organisms in the envucximest. and the nature and amount of dioxins and furans from the w ious sources. If we are to reduce the amimna of toxic dioxins and furans in ocr environment, we need to deal both with the huge amomts already aemed, and the processes that continue to aeste them. What ippens to be the Isrgen amount af taxie dioxins n l farn a is buried in lsd filb or stared at farmer manufacturing sites. We need to develop safe yet jiacticil ways to desroy this waste or ensue that it is contained. We may also need to reduce the amounts of dioxins and Anns occurring as u n rated contaminants of some p "** Graft rednaiona 72 Dioxins and Furms GENP011362 784173 to % have been made in certain products in the pea, rod A n te reduction nay be necessary. The i>nphrri needs tn be on preventing their creation during the enroufjctnriag Finally, we need to reduce the unwanted creation of dhurins and Asms during combustion. For example, inonaator t can bo opaated under conditions (Ugh tempentmes, complete btaning) that reduce the tarinw ot difirms ind futans (USEPA, 1988b). 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Appendix The Virtually Safe Lifetime Daily Dose (VSD) of 23.7.8-TCDD is that quantity of 23,7,8TCDD estimated to cause a maximum of one tranor in one million people who are exposed for 70 yean, In other words, one person faces a maximum one in one million risk of a tumor due j to 23,7,8-TCDD dining their lifetime, if they are exposed to the VSD of 23,7,8-TCDD far their | lifetime. ! i Virtually Safe Lifetime Daily Dose of 23,73-TCDD, from the U-5. Environmental Protection Agency 6 femtograms/kg/day A fenuogiam is 1 x 1CUgrains or 1 quadrillion* of a gram. Note: The USEPA has proposed to increase this daily dose to 100 femtograms/kg/day. Virtually Safe Levels of 23,7,8-TCDD in Soil and Water, from the USEPA jSoil: Below 1 ppb requires no immediate action (from the U.S. Center for Disease Control's recommendation for Times Beach, Missouri). i Water 13 parts per quadrillion (13 x Iff" gtams/Iiier). The Advisory for Fish Contaminated with 23,7,8-TCDD, from the UJS. Food and Drug Administration | Fish with levels of 23,7,8-TCDD above SO ppt should not be eaten. Fish with levels from 25 to 50 ppt can be eaten twice a month. i 1 Fish with levels below 25 ppt can be eaten with no restriction. j (These levels can also be used for 23.7JB-TCDD in other foods). ' j Dioxins and Furans 91 764A 92 GETSIP 011381 % il Recommended Reading For a succinct, informative pamphlet (fast summarizes the health risks of 2J.7.8-TCDD in an cosy-to-read style: "Dioxin in the Environment: Its EfTect on Human Health" 1986. Available from the American Council on Science and Health, 47 Maple S t. Summit, NJ 07901. Telephone (201) 277-0024. Price is S2 per copy. For a well-written synopsis of the issues surrounding 23,73-TCDD and the relevant scientific information: "Dioxin" by F. H. Tschirfey, in Scientific American. February, 1986. Volume 254, Number 2, pages 29-35. Available from Scientific American. 415 Madison Ave. New Yaric, NY 10017, Attention Rosa Davis. Cast of issue is $4. Far a book that discusses in detail the issues surrounding 23.7,8-TCDD, especially the incidents that received the most publicity in the U.S.. and includes much of the relevant scientific infannaiion on 2J.73-TCDD: Dioxin^ Agent Orange by Michael Cough, 1986. Plenum Press, New York. For a summary of the current research findings on dioxins and (urais, consult the proceedings of the annual International Symposium on Chlorinated Dioxins and Related Compounds, published annually in the journal Chemosohere (Pergamon Press). I 92 Dioxins and Finns GBNP 011382 14 784193 %A T W 3-TC D D 2AD JA 5-T CDC ADI CDD CDF congener DNA dioxins rnrans homologue isomer kg LCSO LDSO LOAEL milligram mkrogram nanogram picogram femtogram NCASI NOAEL NOEL NTP PBBl PCBs ppm ppb ppt ppq Q8 USAF USDA USEPA USFDA WHO Glossary and List of Abbreviation 23,7,8-tetracWofodibenzD-pma-dkxiin 2,4-dichlorcphenoxyacetic add 2,4^-tricWorophenoxyoccnc acid United States Centos far Disease Control acceptable daily intake rhifwinatwH dibenzo-p-dioxin chlorinated dibenzo furan a single, particular member of a chemical family deoxyribonucleic add chlorinated dibenzo-p-dioxim chlorinated dibenzo furans a group of dioxins or furans with the same number of chlorine atoms in their structure a single member of a homologue kilogram lethal concentration for 50% of tea organisms lethal dose for 50% of tea organisms lowest-observed-adveiss-effeos level 1 x 10* grams 1 x 10* grams 1 x 10* grams 1 x 10`*grains 1 x grams National Council of the Paper Industry far Air and Stream Improvement no-observed-adverse-effects level no-observed-effect level National Toxicology Program polybraminated biphenyls polychlorinated biphenyls para per million pans per billion pans per trillion pans per quadrillion mkrogram United Stales Air Force United States Department of Agriculture United States Environmental Protection Agency United States Food and Drug Administration World Health Organization Dioxins and Forms 93 784194 & EN P 0Ji33 la d to Author Abtoruzzi, R. 55 Adams, R. 31 Adams, W. 51 Albanese, R, 7, 8, 62, 63 Amendola, G. 21, 37 Bames, D. 16, 17 Baughman, R. 22, 32, 33 Beall, M. 23 Beck. H. 37, 38 Bcnezet, H. 23 Bianco. W. 10 B irnbaum . L 56-59 Bowes, G. 31 Brooksbank. M. 20, 25 Brunner, H. 36 Bumb. R. 41 Buser, H. 14, 31, 40 Carnegie Mellon University 36 CDC 9. 58 Choudhary, G. 28. 46 Cochrane. W. 34 Cockerham. L. 22 Cook, R. 61 Coulsion. F. 4 Courtney, K. 3 Couture, L. 17. 59. 72 Crosby. D. 23. 24. 40. 45 Czuczwa, J. 19, 20, 24, 43, 46, 47 Davies, 1C 27 des Rosiers, P. 31. 40 DiDomenico, A. 24 EngJer, M. 37 Erickson, M. 39, 40 Esposito, M. 7, 33. 35 Faccheui. S. 22 Fairiess, B. 20 Para, G. 63 Fingeriiut, M. 61 Firestone, D. 2, 3, 27 Fishbem, L 61 Fox, G. 55 Gasiewicz, T. 28,51,56 GUbenson, M. 55 Gough. M. 2-4 Gross, M. 21.42 Gupta, B. 52 Hagenmaier, H. 36, 45 Haglund. P. 14 Ha)du, S. 61 Hakansson. H. 64 Hallet. D. 20. 25 Halperin, W. 61 Hardell, L. 61, 62 Harless, R. 22 9a Dtoxins and Furans GENF 011384 Hatch, M. 62 Hauerner-Frey, H. 27 *y. A. 54,60,63 Hty. D. 43 18,22 HondJ, a. 36 Helder. T. 51 S S tt i ! * 43-4* Hornberger. E. 55 Honehar, p. 61 Houk, V. 28 Huff. J. 2-4 Huttinger. 0 . 31,33.36 Lsaixe. A. 25 Jones, G. 25 Kamrin, M. 53 Karasek, F. 43 Kenaga. E. 49. 51 Kimble. B. 42 Kind, J. 9. 58 KjeIler, L 20 Kouuon. J. 52-54. 59 Kocibm, R. 52, 54, 68 Koun. R. 53 Kuehl D. 18, 57, 58 Kunia 62 Kuraaune, M. 62 Lamparski, L. 42 Live, L 68 Lindstrom. G. 28. 47, 58 Marklund. S. 27, 41-44 Marple. L. 25 Masiroiacovo. P. 9. 10, 62 Maaumura, F. 23. 53, 64 Matthews. H. 56-58 Madison. O. 53 McConnell, E. 18, 50 Meaelsoo. ML 22, 33 Moore, J. 54, 58 Mukerjee, D. 26 Munay, F. 68 Nakano, T. 20 Narang, R. 39 Nash, R. 23 NCASI 38,55 Nearick, T. 42 Noren. K. 47, 58 Nom*. L. 49, 51 Narstrom. R. 21. 55 NTP 35. 52, 68 Nygren, M. 27, 28 Oebme. M. 24 OgakkJ. 58 Olie, K. 42 Obon, J. 58 1 1 Dioxins and Furans 95 784196 GENP 011385 OME 55 Ono, M. 27 Oppertuiizen, A. 57, 58 Palausky, J. 23. 25 Pauenon, D. 8 Paustenbach, D. 53. 69 Peterson, R. 54 Pirkle. J. 58 Pilot. H. 53 Pietas, N. 17 Poiger. H. 57 Poland. A. 12. 52-54, 59. 64 Rappe, C. 18. 20. 27. 31-33, 37. 39^1. 43. 44. 47. 57 Reggiaru. G. 6. 55. 58, 60. 62 Robarge, G. 9, 58 Rotard. W. 41 Ryan, J. 8. 26, 57 Safe. S. 12 Sanu, L 10 Sawyer. T. 12 Scheeler, A. 8. 28, 47 Schlauer, C. 57 Schmid, J. 9, 10 Scholz, B. 37 Seveso. Italy 9. 22, 55 Shiraishi, H. 20 Sijm, R. 58 Silbergeld, E. 53 Soikkeii, J. 40 Sparschu, G. 3 Stalling. D. 21 Siehr-Green, P. 6, 63 Swanson. S. 37. 39. 42 Tarkowski. S. 28 Thoma. H. 40, 42 Tosine, H. 34. 36, 44 Travis, C. 27 Tsuji, M. 44 U.S. Department of Commerce 34 Umbren. T. 18 USEPA 4. 6. 15. 19-21. 25. 27. 30, 32-36. 40, 42-46, 48-50, 52-54. 56. 58. 6062, 66, 69 .70. 73 van den Berg. M. 18. 57, 58 Vecchi, A. 54 Vulcan Chemicals 69 Wakirnoto. T. 31. 32 Wassora, J. 2-4 Weerasinghe, N. 21 WHO 28 Wtklimd. K. 61 Wipf, H. 9. 10, 22, 24 Wong. A. 23. 24 Yamagishi, T. 36 Young. A. 22,55 Ynanheikki. E. 28 96 Dioxins and Furans , GENF 011386 [ 784197 1 l a t o to Sablecta Z3,73-subcti&iid isomen accumnlMion of 57 tn human tissue* 26 in organisms 18 Uxudiy of IS 2J.73-TCDD acceptable daily doses from various agencies and countries 66 as a mutagen 54 half-life in orgsnisns 57 half-life in various media 24 in areas sprayed with 2,4,5-T 19, 33 in fish 21 in humans 8,26 in organisms 20 in organisms through use of 2,4,5-T 21 in plants 22 in soil 19 levels in 2,4,5-T 32 levels in Agent Orange 7 solubility in water 25 2J.7J8-TCDD equivalents 15,16 2,4,5-T 3-5 and Z3.7JB-TCDD in cattle 27 and 2 J.7 3 -TCDD in organisms 21 and 2JJ3-TCD D in soils and **"* 19 as a cause of cancer 62 as a souice of 23.73-TCDD 32 breakdown of 2JJ.7.8-TCDD in 23 cancellation of 3 in Agent Orange 7 levels of 23.73-TCDD in 32 2^4,3-trichlofDpheaoi and discovery of 23.7^-TCDD's toxic effects 2 and Seven, Italy 9 ___ and sites contaminated with 2J.7.S-TCDD 19 and Times Beach, Missouri 4 as a souree of dfcxun and A nns 36 manu&asre of 69 1A4) cs a souree of dioxins 34 dktxins in 33 in Agent Orange 7 Abaninas among women in Alset, Oregon 4 among women in Severn, Italy 1 0 ___ in atimals after exposure to 3,73-TCDD 53 A bnprion of dioxins and furans 56 Acceptable dose catentaring in 65 Agent Orange 7-10 Agnus Green, Pink, and Purple 7 Mid WMritnftttw-nfl riw w itw rinw 22 breakdown of 2J.7JS-7CDD in 23 Dioxins and Furans 97 784198 ENP Plug? A lso, Oregon 2,4,5-T and abortions 4 Animals, domestic and wild accidental deaths due to dioxins and limns 5, 9,35 Birth defects attributed to 2J.7.8-TCDD among children in Scveso, Italy 10 among children of Vietnam veterans S in animals 4, 53, 55 in humans 4, 62 Blood dioxins and furans in human 8, 26 Blood constituents effects of dioxins and furans on 54, 60 Breast milk and elimination of dioxins and furans 58 dioxins and furans in 26, 28, 47 Cancer among Vietnam veterans 8 and an acceptable dose of 2,3.7,8-TCDD 67 in animals, caused by dioxins and furans 52 in humans, caused by dioxins and furans 61 CDC and 2J.7.8-TCDD equivalents 17 and Times Beach, Missouri 5 calculating exposure to dioxins and furans 9 risks posed by 2J.7.8-TCDD 69 Chick edema in chickens 2 in Gull colonies 55 Chkncne and birth defects 62 and discovery of 2J,7r8-TCDD*stoxicity 2 and Scveso, Italy LO and Tunes Beach. Missouri 6 Chlorophenols and cancer 61 and occupational exposure to dioxins and furans 28 as a source of dioxins and furans 34-36, 40,45 regulation of 69 Coal as a source of dioxins and furans 42 Dioxins and furans xbeotpooa of 56 __ acceptable doses of 2J.73-TCDD,Emm various agencies 66 breakdown of 23 description of 13 detection of 11 effects on the environment 55 from burning coal and peat 42 Emm burning octi-CDDj/CDFs 42 from bunting treated wood 40 Cram landfills and waste sites 45 from non-industrial sources 46 from paper mills and paper products 37 from the combustion of various products 38 from various products 30 98 Dioxins and Furans GENP 011388 , j 1 j I 1 ' j j j ; 1 \ j I 1 } j | i i | 784199 7 Diarias and Amo (ooat) Ana wood stoves rod botkn 42 faanua cxpos a e to 26 in sir 20,26 ia MV plww 20,27 ia m ala * cootammated sites 22 in drinking warn 20 in food 27 in huauoa 8,26,46 in rriim cnn of lakes and riven 19 in soil 19 mrrhaniani of toxidty 64 metabolism of 57 occupational exposure to 28 I phannacokmerics of 56 ! Unicity of 15 transpon of 24,25 Diphenyl ether herbicides dioxins and funrns in 37 j Environnaital effects of dioxins and Amos 5, 9,55 1 Flame retardants i as sources of dioxins and Anans 39 Food dioxins and furans in 27 Half-life of 2J.7.8-TCDD in organisms 57 of 23,7,8-TCDD in the environment 24 HeuchlorocycJohexsne dioxins and Anns in 37 Heuchloraphene and occupational expostie 28 and Times Beach, Missouri 4 dioxins and funms in 30, 32 present manufacture of 69 Immune System, effects of dioxins and Anans on among people of Times Beach 6 m ang Vietnam veterans 8 in animals 54 inhnmans 63 Incmcraion as sources of dioxins and furans 38,39,43,44 as a sa w of dioxins and A nns 14,20,41,42 Meahoirgn of dioxins and furans 57 as it relates to toxicity 58 Migration of dioxins and furans 24,25 Milk dioxins aid Anna in breast m ilk- see Breast mBk dioxins and Amos in dairy products 27 Movement of dioxins and furans 24, 25 Mutagenic effects of 23,7,8-TCDD 54 Occupational exposure to dioxins and Aims 28 OctfrCDDsCDFs dioxins and Amos Aon the burning of 42 dioxins and A nns from the photolysis of 45 preferential absorption of 57 1 Dioxins and Furans 99 784200 Pape* milli and occupational exposue to dioxins and forms 28 as a source of dioxins and fm ns 21,37 {per sludge, environmental effect] from use of 35 Paper products dioxins and fo n ts to n the bunting of 42 dioxins and fo n ts in 38 PCBs as a source of dioxins and limns 31,43 confounding health effects of 59 dioxins and fonts to n the burning of 39 regulation of 70 Pentachlorophenols and chide edema 3 and dioxins and fonts in food 27 as a source of dioxins and fo n ts 36,40,45 regulation of 35 Pharmacokinetics of dioxins and fonts 56 Photodegtadation of 2^.7,8-TCDD 23 Photolysis as a source of dioxins and fonts 46 Polybrommated diphenyl ethers dioxins and forms to n the bunting of 39 Polychlorinated benzenes and fonnatiaa of diaxim and fo n ts 46 dioxins and forms to n the burning of 40 dioxins and fonts in 36 regulaiionof 69 Polychlorinated diphenyl ethers dioxins and fonts from the burning of 40 dioxins and fonts in 37 Polyvinyl chloride (PVC) dioxins and fo n t] from the burning of 41 Ranch Hands ___ elimination of 2J,7.8TCDD to n 58 * exposure to 2J.7J8-TCDD 8 health of 7 Relative toxicity of dioxins and fonts 15 Reproductive effects of dioxins and forma abortions among omen exposed to 2.4,5-T 4 aboniaos u n rig women to Seven, Italy 10 tn mimils 53 in hamms 62 Severn, Italy 9,22,55 Sewage sludge dioxins rod forms in 43 Stives 4,69 Tetracfakxohyleao dioxins and forms to n the boning of 40 Times Beach, Missouri 5,28,69 Toxic equivalency soars 15 100 Dioxins and Forms GENP011390 i l 784201 I Toxicity of dioxins and furans 15 as related to metabolism 58 factors affecting 1? i in a mixture 16 | in different soils 18 LC30s and LDSOs for various organisms 49 ] mechanism of 64 j NOAELs and LOAELs for various organisms 50 i of a mixture of dioxins and furtns 16 relative toxicity of all dioxins and furans 15 Vietnam 23.7J&-TCDD contamination in 22 and use of Agent Orange 7 dioxins and furans in people of N. and S. Vietnam 46 i 'Vietnam veterans I and Agent Orange 7 . exposure to Agent Orange 8 health of 1.7-9 I levels of 2^,73-TCDD in 8 j Wood dioxins and fiirans from the burning of treated wood 40 | Wood stoves and boilers 1 as a source of dioxins and furans 42 Yusho incident 57, 62 !' i Dioxins and Furans 101 784202 GENP 011391