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17 PCBs--In Perspective Walter L. Bouchard PCBs are very stable compounds which do not break down readily in the environ ment, but instead concentrate as they move up the food chain. Their effects on the environmental species and humans vary due to a number of factors. Walter L Bouchard, M.P.H. is an industrial hygienist for the Arizona Public Service Company, Phoenix, Arizona. PCBs (Polychlorinated Biphenyls) have received much attention recently because of the public's con cerns over their potentially damaging effects on the environment and human health. These concerns have prompted a search for answers to questions about PCEs and how their effects can be controlled This article will broadly outline the PCB problem with emphasis on PCBs in the United States. What are PCBs? The term polychlorinated biphenyls, or PCBs, refers to a class of organic chemicals introduced into United States industry in 1929-1930. A 1979 report by The National Academy of Sciences 1 listed Monsanto In dustrial Chemicals Company as historically the only important U.S. producer of PCBs. Monsanto's plants were located at Anniston, Alabama and Sauget, Illinois, where production of PCBs ended in 1970 and 1977, respectively, PCBs have also been produced, imported or ex ported by a number of other countries Some pro ducers are Italy, France, Japan, the United Kingdom, Austria, Czechoslovakia, the Federal Republic of Germany, Spain, and the U.S.S.R, According to the U.S. Environmental Protection Agency (EPA), countries which have imported PCBs include Finland, New Zealand, Canada, France, Italy, Norway, Sweden, and the United Kingdom. Coun tries which have exported PCBs include France, Italy, and the United Kingdom (EPA 1976). It is Important to be aware of the chemical struc ture and nature of PCBs because it is a critical prere quisite to understanding their toxicity and control. PCBs are man-made compounds manufactured by chlorination of a biphenyl molecule. The biphenyl is composed of two six-sided carbon rings in which one carbon on each ring has joined together. This leaves ten sites for chlorine atoms to join the biphenyl molecule. The number of chlorine substitutions on the molecule corresponds to the ten possible chlorinated biphenyls which may be formed These are monochlorobiphenyl, dichlorobiphenyl. trichlorobiphenyl. etc. Within each of the ten possi ble chlorinated biphenyls, the chlorine atoms may join the rings in various configurations creating many isomers. HONS 206800 1* HMMJ--fuly/Aug 19*0 Typically, the PCBs are sold as mixtures of the various possible chlorinated biphenyls. Commercial PCB mixtures typically contain various con* taminants, including polychlorinated dibenzofurans (PCDFs) and polychlorinated napthalenes. These contaminants have been implicated as being partly responsible for some of the toxicity observed from PCB mixtures. The chlorine content of the mixture is used as one method of describing it. For example, some common PCB mixtures are sold as AROCLOR^ 1243, 1254, and 1260. These contain 43 percent, 54 percent, and 60 percent chlorine, respectively. PCBs are very stable compounds which do not break down readily in the environment, but instead concentrate as they move up the food chain. Their effects on environmental species and humans vary due to a number of factors. The effects of PCBs on envtrotmml.i! sptctes and humans oury due to a number of factors. Use and Distribution of PCBs A 1976 report by Versar, Incorporated, for EPA 'summarizes the various uses and distribution of PCBs. PCBs have been used extensively in many in dustrial applications, but primarily In "closed" or FIGURE 1 PCBs InThcU-S. 1930-1975* M1UJONI PERCENT LBS, STATU J.9 107 107 SJ.4 04 107 inn o SS 190 ISO ttO ISO UHL Oagradad or Inrinaratad Landftlk and dump! Fra* in tha anvitoninan! Currently in uta in Ccpaciton and tramforman Other than electrical inax *4hail iramfar. carbonleu copy papar. hydraulic*, lubricanti. plitlKlirr mat. and othar mncaitjnaoui indinlna! uiea US. cipocti Total US commercial production! ulo `Comkiari from EPA (1970) "semi-closed" systems such as electrical transformers and capacitors, heat transfer systems and hydraulic systems. Much of the PCB marketed to U S. industry is still in service, primarily in electric equipment A significant portion has entered the environment and persistently remains, while the remainder has either degraded in the environment or been destroyed by man. Figure 1 describes estimates of PCB production, use and gross environmental distribution between 1930*1975. Evolution of Concern over PCBs 1929-1975 Over the yean since their fint introduction in the U.S. in 1929-1930, the effects of PCBs have become better known. Reports as early as 1936 described choracne among persons occupationally exposed to PCBs. Later observations noted possible liver effects associated with some human exposures.' In 1968, an outbreak of "Yusho" disease occurred in Japan following accidental human consumption of rice oil contaminated with Kanechlor 400, a PCB manufac tured in Japan (43 percent chlorine). The total number of "Yusho" patients exceeded 1,000. They exhibited a variety of effects which included increas ed eye discharge, acne-like eruptions, hyperpigmen tation of skin and nails and various nervous system effects. Other studies of PCBs showed that they per sist and accumulate in the environment and may cause damage there as well as to humans. By the late 1960s it had become apparent that, while PCBs generally show relatively little acute tox icity, they do show chronic toxicity after accumula tion in the tissues of many biological species, even when exposed to very low concentrations. Some researchers have reported significant widespread PCB contamination In U.S. foodstuffs, human tissue, and throughout the general environment. Industry and government have responded to con cerns over PCB contamination and its effects. By mid-1971. Monsanto voluntarily stopped sales of Arochlors (PCBs and polychlcr rated triphenyls (PCTs for uses other than dosed electrical systems They also offered incineration service for waite li quid PCBs and ended production of the higherchlorinated Arochlors. During 1972 and 197,3 the Food and Drug Administration (FDA) developed HONS 206801 PCBi in perspective rules to control PCBs in food. In 1975 a national con ference on PCBs was held in Chicago. Between the years 1929 and 197S. a span of 46 years, PCBs were controlled mainly through volun tary industry efforts which evolved in intensity and scope. An example of this control is ANSI Standard 007.1*1974 which outlines an Amenran National Standard Guideline for Handling and Disposal of Capacitorand Transformer-Grade Askitrels GfflfaimiiJ Polychlorinated Biphenyls. The year 1975 is a convenient break point in the discussion of PCBs because, in 1976, Congress and the EPA changed the PCB picture radically through broad new federal regulations, These changes will be described later in thus discussion. ' Environmental Distribution and Occurrence : U was mentioned earlier that a substantial amount of PCB has found Its way into the environment "~5ome methods of entry may be through air, water, and land discharge during manufacture and handling of PCB mixtures; PCB equipment manufacture; spills and Teaks during final use of PCB-containing pro ducts; and through leaching from disposal areas. * PCBs become widespread through certain natural and man-made mechanism* and may be found at _ various levels and locations in the soil, air, and water. - PCBs become widespread through certain natural and man-made mechanisms and may h found at various - levels and locations in the sail air, and water. Agricultural soils rarely show detectable PCB levels, however, urban soils do. Soils within city limits show higher levels than suburban soils. Nineteen cities were sampled between 1971 and 1974 in the National Soils Monitoring Program, EPA. Twelve cities showed detectable PCB levels in soils. Many sites were sampled in each city. Typical numbers of positive findings ranged from 0.5 percent--6.3 percent of total samples. Levels of PCBs delected generally ranged from 0.09--3 33 parts per million (ppm). One sample showed 11.94 ppm PCBs.* PCB contamination in urban air has been reported at levels in the range of 100 mg/m1.1 Some U.S. waters and sediment also show PCB contamina tion.* * PCBs are found at various levels in biota One na tional study conducted between 1970 and 1974 by the U.S. Fish and Wildlife Service showed PCB residues in various freshwater fish, mallard and black duck, and starlings* A 1972*1974 study of three Lake Michigan fish species taken in the eastern part of the lake showed mean whole fish concentrations ranging from 5.24-5.66 ppm in bloaters. 10 412 2 ppm in Coho salmon and 12.9*22.9 ppm in lake trout.* Other studies have shown PCBs in ocean dwelling animals.1* PCBs have been found in foodstuffs in the United States. This may include low level contamination in some general food products, commercial fish species and other foods, Researchers are watching closely levels found from early years to more recent, and predicting trends for future yean. 11 11 PCBs hive been found in the general U S. popula tion. Samples of human adipose tissue and milk, col lected in 1973 and 1974 in a national survey, showed that 35.1 percent and 40.3 percent of the samples, respectively, showed 1 ppm or more PCBs on a wet- weight basis; 5-5 percent and 4.9 percent, respective ly, showed greater thin 2 ppm PCBs. Adipose tissue extracts were examined by gas chrom atography/mass spectrometry (GC/MS) and found to contain penta-, hex*-, and heptachlorobiphenyl com pounds most frequently. Less chlorinated isomers seemed to be metabolized and excreted more rapidly In a biological system.11 - One sample survey in Canada showed human con tamination to be about 1-2 mg/kg PCB in adipose tissue in Canadians sampled PCB residues m human milk of Ontario residents were about 1 mg/kg fat.1* Health Effects and Human Exposure There are two major areas of exposure to PCB mixtures which give a reasonably direct indication of human health effects. These are occupational ex posures and one episode of accidental exposure of persons in japan. Reported occupational exposure levels vary Workplace air levels have typically ranged from very low levels up to 10.0 ms/m1 PCBs in air depen MONS 206802 JO HMMJ--JulyiAug 19W ding on environmental conditions; type of operation (for example, electrical equipment manufacture or chemical manufacture); work procedures, and con* trots in effect. Very high levels, in fact up to 06 rng/m', have been reported in exceptional cases. Effects of occupational exposure center on a few major areas and mainly depend on dosage, route of exposure, and individual biological variation among exposed persons. Common effects are skin disorders. These include, but are not limited to, chloracne, hyperpigmenta tion. rashes, and irritation. These effects have been observed both in areas of the body contacted direct ly by PCB mixtures and in areas not directly con tacted. Other effects may Include dry sore throat, upper respiratory irritation, asthmatic bronchitis, eye irrita tion, nausea, gastrointestinal disturbances, headache, duziness, and liver effects. The National Institute for Occupational Safety and Health (NIOSH) reports that there are no adequate studies to confirm or deny that PCBs are car cinogenic; that PCBs have little mutagenic potential, but may alter mutagenicity and carcinogenicity of other compounds by stimulating microsomal en zyme activities; and that teratogenic potential does exist NIOSH further admonishes that there are no reports of infertility or abortions attributed to PCB consumption or exposure, or undesirable effects in children bom to mothers exposed to PCBs in the diet, or undesirable effects developing from nursing such mothers. Based on available data, PCBs should be handled as if they are potentially carcinogenic and potentially teratogenic Recalling the previously mentioned outbreak of "Yusho" (literally translated oil disease) which occur red In japan between 1960 and 1975, approximately 1,500 cases were reported in which patients were found or presumed to have ingested rice oil which was accidentally contaminated with a PCB mixture, Kanechlor 400. Samples of oil contained 000-1,000 mg/kg PCB with some reaching 3.000 mg'kg. Con centrations of polychlorinated dibenzofurans (PCDFs) were in the range of 5 mg'kg. These levels of PCDFs arc about 250 times more than are usually found in PCB mixtures. Intake of contaminated oil was estimated at 2 0 g (10 mg PCDF) among a highly exposed group. Minimum amounts ingested may have been 0 5 g. The effects of "Yusho" are widely desenbed in the literature. In the early stages these include ocular discharge, swelling of upper eyelids, dermatological symptoms mainly associated with follicular keratosis, and various nervous and general symp toms. Other features described are hypertriglyceridaemia with normal plasma cholesterol, adrenocortical and ovarian dysfunction, bronchitis (cough and phlegm), hepatomegaly, hypobilirubinaemia, low immunoglobulin levels and (possibly) disturbed calcium metabolism." While "Yusho1' effects are generally attributed mainly to PCBs. Japanese researchers have suggested a need to investigate the role of PCDFs more fully.11 Effects on the Environment The full impact of PCB contamination on ecological systems is not fully understood However, there have been a number of attempts to summarize currently apparent effects and to estimate future possible impacts. In general. PCBs may cause the following impacts on wildlife when high concentrations of PCBs are en countered! reproductive disorders, increased mortali ty, growth changes, and behavior changes. Other ef fects have been reported. '* ** PCBs resist degradation in the environment and persist for long periods of time. As they persist, they tend to accumulate in animals as they move up the food chain. This is most strongly demonstrated in aquatic ecosystems. 11 **w w w In any biological system, effects depend, among other things, on dosage, route of exposure, and various species and individual biological factors. Controlled Studies of Toxic Effects Controlled studies typically involve dosing various animal species with lethal or sublethal levels of a test chemical under well-defined conditions Depending on the route of administration (oral, in halation. dermal applications, etc.), the dose. the specific test species, individual biological factors and other factors, one can draw reasonably well defined HONS 206803 PCBs in pmpeibvc II conclusions about the possible toxic effect of a chemical on man. The results of the studies noted below suggest a possibility of similar effects in man. However, one should bear in mind that animal data are not directly extrapolatable to man without careful evaluation of differences between the actual test species and man, the levels of exposure used in the experiment and many other factor*. A 'Criteria Document" prepared by NIOSH in 1977 gives an exhaustive review of some important studies.1 The absorptions, distribution and excretion of PCBs have been described in various animal studies. PCBs are readily absorbed into the body from the digestive tract and respiratory system. Depending on the degree and pattern of chlorination, they are ex creted in the feces, milk, and hair of animals. Trace amounts are excreted in the urine. Metabolites of PCBs have been found in the urine, feces, and milk of mammals. Among mammals there appear to be quantitative differences in FCB metabolism and effects related to age and sex. In general, the lower chlorinated biphenyls are more rapidly metabolized than the highly chlorinated ones, which may persist in tissues for yean after in take has been discontinued. Some metabolites found in urine, bile, feces and milk indicate that, at some point, PCBs may be metabolized to highly toxic arene oxides with may present a potential risk of car cinogenesis or mutagenesis. Inhalation and dermal application studies of PCB mixtures in animal tesb show a variety of effects. In halation studies show changes In liver, kidney, heart, spleen, thyroid, blood and growth rates. Dermal studies show changes in skin, liver, and kidney which suggests that PCBs may be absorbed through the skin Some of the toxicity demonstrated by some PCB mixtures may be due to contamination by PCDFs, Administration of PCBs to test animals by the oral route is the most common type of study. Oral dosage studies show that as the degree of chlorina tion increases the acute toxicity decreases. Effects observed include, but were not limited to, some im munosuppressive activity,- changes in the liver, kidney, skin, blood, protein levels, DNA levels and RNA levels; growth changes; gastrointestinal distur. bances; and loss of body weight. Animal work done on reproductive and teratogenic effects of PCB mixtures shows that PCBs appear capable of crossing the placental barrier and having an effect on reproductive performance There is some evidence of the possible mutagenic and cytotoxic potential of PCB mixtures One study using the Ames bacterial test showed that, as the degree of chlorination decreases, the mutagenic potential increaises. The more highly chlorinated biphenyls showed very little mutagenic activity The cytotoxicity of PCB mixtures increases with decreas ing chlorination. Tumors have been produced by PCB mixtures in a variety of animal test systems Liver tumors were typical. Tumors of the pituitary gland have also been observed. Regulatory Requirements The Federal Government has taken an approach to regulation of chemicals In the U.5. that includes cradle-to-grave cognizance over their import or pro duction, transport, handling, and disposal. PCBs fit into this regulatory philosopy. There can be some problems in living with government rules. There are at least four U S. government departments or agencies administering six laws which, in part, cover PCBs. Some regula tions overlap confusingly, or are vague. Smaller businesses in the regulated community, which typically have small or nonexistent environmen tal/legal staffs, can be overwhelmed by the synergistic effects of these regulations. It it clear that if iht US. refit!litcry system is to be invoked in PCB control, clearer, ntert reasonable and more effectively-coordinated rnlts should bt provided. It is dear that if the U.S. regulatory system is going to be involved in PCB control dearer, more reasonable and more effectively coordinated rules should be provided. Some of these rules arc listed below by agency or department. This list is extensive, but not meant to be all inclusive. HONS 206804 21 HMMJ-july/Au*. 19*0 Enoironmenlal Protection Agntcy (PA) Toxic Substances Control Act (TSCAH section 6e mandates broad control over manufacture, distribution, handling, and disposal of PCBs (refer to Ftdtral Register May 31. 1979). Resource Conservation and Recovery Act (RCRAJs mandates specific rules to regulate various aspects of disposal, Federal Water Pollution Control Act (FWPCAH mandates rules to regulate discharges of PCBs to waterways. Department of Transportation (DOT) Hazardous Materials Transportation Act (HMTA): mandates rules to regulate transportation of PCBs. Food and Drug Administration (FDA) Food, Drug and Cosmetic Act: mandates rules to regulate PCB residues in foods, etc Dqxtrtmmi of Labor (DOL) Occupational Safe ty and Health Act (OSHAH mandates rules to regulate occupational ex posures to PCBs. Summary In response to the scientific evidence which in dicates a potential problem from PCB overexposure, and because of the need to comply with existing laws and regulations, the following goal is appropriate for most applications: Persons who use PCBs should completely identify the disposition and quantity of all PCBs in their system; conhol its use by insuring it remains in a closed system or is quickly and ade quately cleaned up in the event of a spill, or other wise handled safely during necessary handling opera tions; and ultimately remove all PCBs from their system foi safe disposal and substitute PCB equip ment with non-PCB equipment as old gear wean out. References 1, National Research Council, PolychknnateH Biptimy/i Washington D.C.: National Academy of Sciences, 1979. 2. US. Environmental Protection Agency. PCBs m iht United States, Industrial Uu and Ejirsonmcntul Dutnbution, P8-252 012. Springfield, Virginia: National Technical In formation Service, F22-23, 1976, pp. 1-2. 3. US. Department of Health, Education and Welfare, Public Health Service, Center for Disease Control Na tional Institute for Occupational Safety and Health. Cntena for a Recommended Standard.. .Occupational Exposure to Polychlorinated Biphmyk, Washington D C; Superintendent of Documents, September 1977, pp. 27-123. 4. Carey, A.E. and Gowen, J.A, PCBs m Agricultural and Udm Soil In Proceedings of the Nation*/ Conference on Polychlorinated Biphtnyh, Chicago, 1975, E PA-560/6-75 004. Washington D.C..- US, Environmental Protection Agency, 1976, p. 195-196, 5, Kutz, F.W, and Yang, HS.C. A Note on Polychlorinated Biphenyls m Air. In Proceedings of the National Conference on Pofychlormated Biphenyls, Chicago, 1975. EPA-560/6-75-004. Washington D.C,: US. Environmental Protection Agency, 1976, p. 162. 6. Dennis, DS, Polychlorinated Biphenyls in the Surface Waters and Bottom Sediments of the Motor Drmmage Basins of the Undid States. In Proceedings of t!k National Conftmee on Polychlorinated Biphenyls, Chicago, 1975, EPA>560/6-75-004 Washington D C. U-S. Environmental Protection Agency, 1976, pp. 163>194. 7, Young. D.R.; McDermott, D ] and Heesen, T. C. Marini Inputs of Polychlorinated Biphenyls off Southern California In Proceedings of At National Conference on Palyehlenrailed Biphenyls, Chicago. 1975, EPA.S60/6-7J-004. Washington D.C.: U.S. Environmental Protection Agency. 1976. pp. 199-206. 6. Walker, C.R. The Ociunence of PCB m tie F< h and Wildlife Monitoring Program In Proceedings of i-n Njii.-j/ Conference on Polyihlonnnted Biphenyls. Chieaga 1975. HONS 206805 PCBs in perspective iJ EPA-560/6-75-004. Washington D.C.- U-S. Environmental Protection Agency, 1976, pp. 161* 176. 9. WiU/ord. W.A.: Hesselberg. R.J. and Nicholson, I.W. Trends of Polychlorinated Biphenyls in Thru LitIt Michigan Fishes. In Proceedings of the National Conference on Polychlorinated Bipirrnyl*, Chicago, 1975, EPA-560/6-75-004, Washington D.C: U.S, Environmental Protection Agency, 1976, pp. 177-I6L 10. McDermott, D. J.; Young, D.R, and Heeser, T. C. PCB Contamination of Southern California Mormt Organism. In Proceedings of Iht National Conference on PolyehlonnateJ Biphenyls, Chicago, J97S, EPA-560/6-75-004. Washington D.C.; US. Environmental Protection Agency, 1976, pp. 209-217. 11. Jelinek, C F. and Comeliusten. Levels of PCBs in the US. Food Supply. In Proceedings of the National Conference on Polychlorinated Biphenyls, Chicago, 1975, EPA-560/6-75-004, Washington D.C: U.S. Environmental Protection Agency, 1976, pp. 147-154. 12. Graham, J.M. Levels of PCBs m Canadian Commercial Fisk Spades. In Proceedings of die Notional Conference on Polychlorinated BipNnyls. Chicago, 1975, EPA-560/6-75-004. Washington D.C: US. Environmental Protection Agency, 1976, pp. 155-160, 13. Kutz, F.W. and Strastman, SC Residues of Pofythlorinatid Biphenyls m ihe General Pspnhslim of On United States. In Precesslinp of the NoHonol Conference on Polychlorinoted Biphenyls. Chicago, 1975, EPA-560U6-75-004. Washington D.C.: US. Environmental Protection Agency, 1976, pp. 159145. 14. Grant D-L- Me*, JL and Frank. R. PCB Residues m Human Adipose Them and Milt. In Proceedmp of Iht National Conference on Polychlorinated Biphenyls, Chicago, 1975, EPA-560/6-75-004. Washington DC: US. Environmental Protection Agency, 1976. pp. 144-146. 15. Stendall. R.C. Summary of Retent Infomnhon RrforJing Effects of PCBs on Birds and Mammals In Proceedings of rhe Na tional Conference on Polychlorinated Biphenyls. Chicago. 1975. EPA-560/6-75-004. Washington D C,, U S Environmental Protection Agency, 1976, pp. 262-267, 16. Walker, CR. Prt-1972 Knowledge of Non Human Ef fects of Polychlorinated Biphenyls. In Proceedings of the National Conference on Polychlorinated Biphenyls, Ch-cago. 19?i, EPA-560/6-75-004. Washington D.C.: US. En\ ironmental Protection Agency, 1976, pp. 266-251. 17, Hansen, D.J. PCBs: Ffftcts On and Accumulations By Estuanne Organisms. In Proceedings of the National Conference on Polychlorinated Biphenyls, Chicago. 1975, EPA-560/6-75-004. Washington D.C.: US. Environmental Protection Agency. 1976. pp. 252-265. 16, Nebeker, A.V. Summary of Recent Information Regard ing Effects of PCBs on Freshsoaler Organisms, In Proceedings of the National Conference on Polyeklonnated Biphenyls, Chicago, 19 75, EPA-560/6-75-004. Washington D.C.. US Environmental Protection Agency, 1976, pp. 264-291. 19. US. Environmental Protection Agency. Catena Docusntnl for PCBs, re-255 597. Springfield, Virginia: Na tional Technical Information Service, 1976. 20. IARC Monograph on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Polychlorenated Biphenyls, Volume 16, 1976. 21. Kuratsune, M.; Matuda, Y. and Nagayama, J Some of the Recent Foldings Concerning Yusho. In Proceedings of Iht No tional Conference on Polychlorinoted Biphenyls, Chicago, 1975. EPA-560/6-75-004 Washington D.C: U S Environmental Protection Agency, 1976, pp. 14-29. HONS 206806