Document v60EkwyQRRN314dznwZDn8Zbb

feature PCB's-prevalent and persistent Intensified research is needed to minimize their dangers Carl 0* Qustafson, Federal Water Quality Administration, Athens. Ga. I Purina the past three years, a special class of compounds, called polychlorinated biphenyls ( pcb's), has claimed the attention of ecologists and pesticide analysts in this country. These compounds were not discovered in the environment until 1966 in Swe den and 1967 in the U S., despite the fact that they have been available com* mercially for 40 years. Interest in pcb's has arisen because they are frequently found in fish, bird, water, sediment, and other environmental samples when such samples are examined for chlori nated pesticide residues. That a wide variety of samples containing pen's has been collected from England, Scandi navia, The Netherlands, Antarctica, Central America, and many different parts of the U.S. makes them truly ubiquitous pollutants. Polychlorobiphenyls are made by substituting chlorine atoms for one or more of the hydrogen atoms at the The Monsanto Co. stated recently In a letter to Congressman William F. Ryan of New York that as of August SO, It would no longer sell ecu's to custonters for use In general plasticiser operations where disposal of the endproducts cannot he controlled. After some lag period--the time It takes to eventually dispose of the products made from pen's and currently In processor's Inventories--the quantity of pen'r getting Into the environment may he substantially reduced. If Monsanto's former customers look for pen substitutes, rather than purchasing rca'j from manufacturers In Japan and Europe, the protected decrease could become a reality. Carl Q. Qustafson 114 EnrirsnairKlal Scfenca 6 TmImioIobp numbered positions of the biphenyl structure. In the process of replacing hydrogen atoms with chlorine atoms, a large number of substitution combinations arise. For example, three monochlorobiphenyl isomers are possible, 12 dichlorobiphenyl isomers, 21 trichlorobiphenyl isomers, and so on. Theoreti cally, 210 compounds can be prepared by this substitution process; a typical example would be 2,4,6,2'4'-pentachlorobiphenyl. Whenever aromatic hydrocarbons such as biphenyls are chlorinated, the product is a mixture of compounds, in cluding isomers. It it quite difficult to synthesize single, specific chloro biphenyl compounds In the laboratory unless involved procedures are em ployed. Consequently few of the indi vidual compounds have been prepared in the pure form for study. In the commercial process for pc* manufacture, biphenyl is chlorinated with anhydrous chlorine in tall cy lindrical towers with either iron filings or ferric chloride as the catalyst. The by-product is hydrogen chloride; the product is a mixture of several pcb's. The degree of chlorination is deter mined by measuring the specific gravity of the mixture or, when the product is more viscous, the bail-and-ring soft ening-point test is used. The whole pro cess takes from 12 to 36 hours. In the U.S., the sole manufacturer of pea's is the Monsanto Co., which markets them under the trade name Aroclor. pcb's are also manufactured in Europe and Japan, under trade names such as Phenochlor and Clophen. The various Aroclon are dif ferentiated by a four-digit number, with the last two digits indicating the percentage of chlorine in the mixture. Properties The three most important physical properties of the pcb's sre low vapor pressures (they have high boiling points), low water solubility, and high dielectric constants. They are mis cible with most organic solvents and compatible with many types of poly mers. Although some individual polychlorobiphenyl compounds are crys talline, the Aroclor mixtures are either liquids or resins. The chemical properties that make pcb's desirable industrial materials are their excellent thermal stability, their strong resistance to both acidic and basic hydrolysis, and their general in ertness. They are quite resistant to oxidation. Monsanto reports, in a tech nical bulletin on pcb's, that they can be heated to 140 C. under 260 p.s.i. of oxygen pressure "without showing any evidence of oxidation at Judged by de velopment of acidity or formation of sludge*" The physiological properties of the pcb's make them potentially significant contaminants of the environment. For any pollutant, two factors are involved: acute toxicity, which is immediately evident because of a high death rate or other maiming effect; and chronie tox icity, which is the result of a slow ac cumulation of the poison in the body and is a sublethal effect. Whenever acute toxicity is high, pollutant will be readily recognized and appropriate remedial actions wilt be introduced. If, on the other hand, acute toxicity is low. MONS 087334 the physiological effects will fo un noticed until the chronic effects make themselves evident. When this happens, the problem mey have advanced be yond immediate or easy correction. Aesite tealelty All studies of pcb's in animals indi cate that acute toxicity is not a signifi cant factor. Their acute toxicities are on the order of those of other chlori nated aromatic compounds. Monsanto has sponsored two investigations of the acute toxicities of Aroclor mix tures. In the first, at the Kettering Laboratory at the Univeraity of Cin cinnati. Dr. I. F. Treon and his co workers investigated the toxicity of Aroclor vapors for guinea pigs, mice, rabbits, and rats. All animals survived s 24-day exposure to 0.83 p.p.m. of Aroclor 1242 for 7 hours per day on 17 of those days. Even after more pro longed tests, there were no severe ef fects from Aroclor 1242. In the second investigation, still in process, three groups of beagles are fed Aroclor 1242, 1254. and 1260. respectively, at a rate of 100 p.p.m. in their diets. After three months no significant abnormalities have been noted. Similar studies on fish have been per formed in several laboratories. Dr. dieldrin or dot. As with fish, their tox icity appears to be inversely propor tional to the chlorine content of the mixture. Bated on the above data, it ia un derstandable why the poiychlorobiphenyls, commercially available for 40 years, have only recently attracted attention as toxic environmental con taminants. Chronic toxicity The chronic toxicities of pea's pre sent a more disturbing situation; several chronic effects have been observed. It was discovered, quite by accident, that pcb's have a toxic effect on chickens. Professor E. L. McCune and his co workers at the University of Missouri found their chickens dying after they were placed in a feeding house, parts of which had been freshly painted with an epoxy paint. Careful investigation revealed that the toxic factor was Aroclor 1242. a binder in the paint. When Aroclor 1242 was fed to the chicks it produced the same characteristic effects as chick edema factor. McCune re ported : "Gross pathology included hy dropericardium, hydroperitonium, en larged heart, liver, and kidneys, and hemorrhage of internal organs. Mi croscopically the kidneys showed marked tubular dilation and oumaroua casts." Another chronic effect of pen's ia related in wildfowl. The accumulation of high concentrations of chlorinated hydrocarbons in birds resulted in dis ruption of normal breediog behavior and in the formation of thin-shelled eggs. A dramatic example of this effect has been observed in the cam of thn brown pelican. On the Anacapa Islands off the California coast, no young wart hatched last year from 300 pain of nesting birds. The shells of most eggs laid were so thin that a dent occurred when the egg was picked up. There are two possible causes for the laying of thin-shelled eggs by wild fowl. One is a low calcium reserve in the bird; the other is the inability of the bird to deliver the needed calcium to its oviduct, where the eggshell ia forming. The calcium level In the avian biosystem and the calcium reserve in the secondary bone structure or medul lary bone, found only in female birds when they are breeding, are controlled by the hormone estrogen. A high es trogen level is associated with ths for mation of this calcium reserve. Chlo rinated hydrocarbons, such as dot. Richard Schoettgcr of the Sport Fish eries and Wildlife Fish-Pesticide Re search Laboratory in Columbia. Mo., reports that 96 hour-TLfln toxicities of the Arodors to trout range from 1.17 to iso p.p.m. Compared to dot, whose 96 hour-Tt.%,, toxicity is 0.002 to 0.009 p.p.m. for trout, the Pen's have a rela tively low acute toxicity. With the more sensitive htuegill, the 96 hour-TLfl(, for Aroclor 1248 is 0.278 p.p.m., while that of dot is 0.008 p.p.m. Aroclor tox icides appear to be inversely propor tional to the chlorine content of the mixture. Shellfish, oysters, and shrimp are more sensitive to pea's. Dr. Tom f Duke, at the Bureau of Commercial l Fisheries Pesticide Field Station, re- I ports 100% mortality of juvenile pink I shrimp exposed to 0.10 p.p.m. of AroI dor 1254 in water for 48 hours. This | concentration of Aroclor 1254 will k cause a 100% decrease in shell growth of oysters after 96 hours. To achieve the same effects with dot in these ex periments, only 0.0006 p.p.m. and 0.01 p.p.m., respectively, were required. There is very little evidence that pen's are toxic to insects. Studies to date show that they arc less toxic than Volume 4, Number 10. October 1970 SIS I I MGNS 087335 chlordane, dieldrin, and pcb's, activate ensymet in the liver which transform estrogen into a more water-aoiubie compound that it readily eliminated from the bird'* body. This meant that when eatrofen levels are tow, calcium reserves will alio be low. and there* fore very little calcium will be avail* able for strong eggshell production. Dieldrin and Fee's are more effective than dot in this type of enzyme-induc tion activity. Aroclor 1262 hat an es tradiol degrading potential four to five timet that of p.p'-dob or technical grade dot. The ability of the female bird to deliver calcium to her oviduct during the last 20 hours, when the eggshell is being formed, is related to the func tioning of the enzyme carbonic anhydrate. When birds that have ex hibited the ability to lay normal eggs are injected with a metabolite of dot (nor) just prior to the formetion of the eggshell, they will lay thin-shelled eggs. This indicates that dot also in hibits the activity of carbonic anhydrasc, the enzyme that controls the flow of calcium from the blood stream of the bird into its oviduct. Since dieldrin seems to have no effect on carbonic anhydrase, we may assume that neither do the pen's. How ever, these compounds delay breeding time significantly. Many ornithologists feel that late breeding has a stronger influence on the reduction of bird populations than does the laying of thin-shelled eggs. If this is true, pen's are a more potent threat than dot to our declining bird populations, es pecially for predatory birds that ac cumulate fairly high levels of pen's be* cause they eat smaller animals that al* ready have concentrated pen's in their own tissues. Other investigators have produced evidence to show that pci's are simi lar to dot in their activity. Dr. Joseph Street at Utah State University has shown that when pen's accumulate in the liver, they induce mlcroaomal en zyme activity by bringing about more rapid metabolism of drugs, insecticides, and other foreign compounds. He fed rats a diet containing JO p.p.ni. of Aroclor 1254 or Arocior 1260. After 10 days on this diet, the lest animals were administered hexoberbitol at a dose of 100 p.p.m. to induce sleep. In comparison with a control group, the sleeping lime for these rats was reduced by 65 to (10%. Street also found that Aroclor, when fed at the Ilf Emtrenmfntal Science A Technology \l<r same level, will reduce dieldrin stor age in adipose tissue by 90 to 95%; in crease aniline oxidation by 200 to 300%; and increase bpn detoxication by 430 to 470%. In addition, the pea's cause activation of organothiophosphate compounds, which adversely af fect the system. This letter effect coun terbalances the detoxification of diel drin. Normally, when a substrate activates an enzyme, it is converted to a watersoluble form that will be eliminated from the system; however, this is not the case with pcb's. Because they re main in the system for prolonged pe riods of time, their enzyme induction activity is always present. In this way the normal concentration of important body chemicals may be lowered to the point of bringing about malfunctUms in the system. For example. Street be lieves that the pcb's bring about steroid degradation, which can lead to altered endocrine relationships. The chronic toxicity to man is ae follows: Like the chlorinated naphthalenes, the chlorinated diphenyls have two distinct actions on the body, namely, a skin effect and a toxic action on the liver. The lesion produced in the liver is an acute yellow atrophy. This hepato-toxic action of the chlorinated di phenyls appears to be increased if there is exposure to carbon tetrachloride at the same time. The higher the chlorine content of the diphenyl compound, the more toxic it is liable io be. Oxides of chlorinated diphenyls are more MONS 087336 toxic than the unoxidized ma terials. The skin lesion is known as chloracne, and consists of small pimples and dork pigmentation of the exposed areas, initially. Later, comedones and pustules develop. In persons who have suffered systemic intoxication, the usual signs and symptoms are nausea, vomiting, loss of weight, jaundice, edema, and abdominal pain. Where (he liver damage has been severe. Ihe patient may pass into coma and die. Sax, N, Irving, "Dangerous Propertln of Industrial Materials." 3rd edVan Noxtrand-Reinhoid, New York. 1968. The ubiquity of pen's is related to the wide spectrum of applications that have been found for them. The largest single use of rat's it related to their electrical properties--as coolant-insu lation fluids in transformer*. For this purpose the Arodors arc also sold under such trade names as Chlorcxtql (Allis-Chalmers Mfg. Co.), Dykanol (Federal Pociflc Electric Co.), Inerlecn (Wcstinghousc Electric Co.), Noflamol (Wagner Electric Co.), Pyrnnoi (General Electric Co.), and Thcrminol (Monsanto Co.). Other uses of pen's include formula tion into ballasts for fluorescent fix tures; impregnation of cotton and as bestos for braided insulation of elec trical wiring; a plasticizer in wire and cable coatings; capacitors and askarcltype transformers; and plasticizers of vinyl ch'oridc polymer films. Because of their thermal stability and fire re sistance, the Pen's alto find application in high-pressure hydraulic fluids, spe cialized lubricants and gasket sealers, heat transfer agents, and machine tool cutting oils. Miscellaneous uses in clude: formulation into some epoxy paints; protective coatings for wood, metal, and concrete; adhesives; and in carbonless reproducing paper. One of the primary manufacturers of carbonlets reproducing paper also sella Arccion in an encapsulated form. Oeneraily the kinds of applications described above mean that the pcb's will be in many types of products that eventually find their way to the domestio market. When used in manufacture of ballasts for fluorescent fixtures they will be found In kitchens, bathrooms, stores, and offices throughout the coun try. Wherever office forms are used that do not use carbon paper, one may find pen's formulated into the microcapsulcs of dye that comprise the re Oat chromatogram A it of a standard pesticide mixture, B It typical of Arodor 1294. and A + B It the chromatogram of a 50 : 50 mixture of both. The concentration of Arodor 1254 it approximately 10 timet those of the pesticides In A, hence it It un* deretandable why PCB's were not readily recognized in pesticide chromatograms. Oat chromatograph (Packard 7620) conditions: gat flow 80 ml./min. nitrogen; tarn- paraturas---oven. 210* C.. Inlet, 230* C., detector. 218* C.; Nl* electron capture detector; 5' x gleet column packed with 8% SE-30 on Chromotorb Q 80-90 math. producing layer of the business form, pen's have also been found on the transparent receipts used in credit card charge forms. Aa plasticizers they can be expected to appear in many con sumer plastics. Since the chronic tonicities arc so significant, it becomes important to know just how extensively (he pcb's are distributed in the ecosystem, and just how they find their wav into the environment. Rainwater in En gland, brown seals off the const of Scotland, white-tailed eagles in Swe den, cod in the Baltic Sea, mussels in The Netherlands, adelie penguin eggs in the Antarctica, brown pelican egga in Panama. Arctic term, shrimp in Florida, river water in Japan, waters in the Great Lakes, human hair, and human adipose tissue--samples of all these have been found to contain rtn'i. MQNS 037337 Volume 4. Number to. October 1*70 817 thin mkln, them dm of widely <r dlipinid pollutants. II--diiy iimtii The properties of pcb's tbit make them industrially useful are the tune properties that cause them to persist in the environment. These in clude thermal stability, resistance to oxidation and hydrolysis, solubility in a wide rente of organic solvents, water Insolubility, high dielectric constant, and compatibility with many types of macromolecules. Their resistance to oxidation and hydrolysis also makes pci's more stible and persistent than dot. Consequently, they could even tually accumulate to a higher concen tration than dot, especially if the use of ddt is sharply curtailed in the U.S. The solubility of pea's in nonpolar solvents explains why they ere reedily absorbed inlo fatty tissue and into the liver. Their resistance to oxidation or other types of chemical degradation explains their persistence In the en vironment and accumulation in animal tissue. The latter effect is enhanced both by their insolubility in water and solubility in organic solvents. Their chemical inertness and resistance to metabolism account for their low acute toxicity. But as (hey slowly build up in a living system their con centration approaches toxicity levels, st which point chronic effects make themselves evident. It hes been established that Ash-eat ing birds will accumulate lerge concennations of pci's, as in the case of the white-tailed eagle, which hat been found to have as much as 14,000 p.p.m. of pcb's. Peregrine falcons, taken off the coast of California, were found to have as much as 2000 p.p.m. in their lipid tissue. When shrimp were exposed to 10 p.p.b. of Aroelor 12S4 for 46 hours, they accumulated 1300 p.p.b. of pcb's, which raprsasnts a 130-fold con centration is very short time. Oysters, exposed to an Mantlcal concentration of Arodor 1254 for 96 hours and then plaoed in PCB-frve water for four days, still had a concentration of 33,000 p.p.b. of pcb's, which constitutes a 3300-fold concentration. This means that even though the concentrations of pci's are in the parts-per-billion range in the environment, their high lipid solubility causes them to collect in fatty tissues of lower animals and marine life. Therefore, species at the top of a food chain will also accumulate pcb's In their bodies, particularly in their lipid tissue and liver, in much the same way a* they accumulate dot and other chlorinated pesticides. Because of the low solubility of pcb's in water, when a solution or dispersion of them is discharged Into a river or lake, they wilt accumulate on the sedi ment in relatively high concentrations. Subsequently, they will redissotve very slowly in the water as conditions change. Therefore, it will usually take a long time to flush out a contaminated area. Accidental oeeurrence The reason that pcb's have not been found in the ecosystem as extensively as dot. and are not present in environ mental samples at as high a concen tration as dot, is (hat pcb's And their way into the environment accidentally. ddt is deliberately spread because this is the only way its insecticidal proper ties can he utilized, pcb's are not in tended to get Into the environment, but they do because their unique chemical properties prevent them from being de stroyed by our usual waste disposal methods Thus, they inadvertently es cape and become widely dispersed. In Sweden, where the use of dot has been banned, and where the main power source is hydroelectric, investi til larirs--uwtel Brients A Tsdmeieiy gators And that the concentration of pcb's in the environment is as high at that of dot. There are several ways by which pea's get into the ecosystem. One of these is by incineration. Products con taining pea's, such as carbonless re producing paper In business forms, plastics (especially polymer Aim end sheeting that contain pcb's as plasti cizers), spent ballasts from fluorescent light Axtures, and objects coated with pea-formulated coatinp, all And their way to the city dump or incinerator for burning. The pcb's do not burn but are vaporized. They are then carried into the atmosphere, where they collect on particulate matter and are subse quently returned to the surface of the earth, into the rivers, lakes, and oceans. In this way they become widely diatributed throughout the global environ ment. Another source is probably land run-off from industrial wastes and dumps. A third source is the point of manufacture and the plants where pcb's are processed into other products. They can escape through the (riant ven tilation and exhaust systems inlo the atmosphere and through its waste treat ment system into sewers or directly in waterways. MONS 08733d Il ii interesting to note that the inci dence of rce'e in environmental tem ples is highest in industrialized and ur banized areas. Birds whose primary habitat is the San Francisco Bay area have a larger concentration of pen's per unit of body weight than those lo cated in Baja, Calif., which is com pletely rural. Aquatic life in the Archi pelago of Stockholm, the most indus trialized area of Sweden, were found 10 have a higher concentration of pen's than fish samples taken from the west ern coast of Sweden, a lew developed .ircii. Sediment samples taken from -outhern portions of l.akc Michigan .invc n higher concentration of pea's :hmt those front other parts of the lake. Monsanto states that until a recent change in marketing policy (see inset, page 814). sales of Aroclors were in creasing at the rale of 8% per year. While this increase docs not seent sig nificant, it may he important if the in creased consumption was in consumer products and thus would find their way into our normui solid waste disposal -ystems. Such an occurrence would mean a definite increase of rnt residues in the environment, and therefore a marked increase in their chronic tox icity effects. Detection pen's were not discovered in environ mental samples until very recently for several reasons. First, as indicated shove, they have not been deliberately distributed about the ecosystem. Sec ondly, because of their relatively low acute toxicities, their prrsencc was not immediately evident. Finally, they are difficult to delect analytically. The pen's were first detected as in terfering peaks in the gaa chromato graphic analysis (oc) of environmental sample* being analyzed for chlorinated pesticide residues. When Pen's are pres ent in a sample they give a pattern of several oc peaks, whose retention times arc similar to those of dieldrtn, dot, one, aldrin, and heplachlor oxide. Be cause the peaks were not large or sharp, investigators tended to ignore them until S. Jensen, in Sweden, and R. Ritcbrough, at the University of California at Berkeley, identified them ns corresponding to common constitu ents of environmental samples being analyzed for persistent pesticides. The problem of the interferences of pen's with the analysis of other chlori nated pesticides has been largely over come by prior treatment of the sam ple. Several investigators have used column chromatography to separate pen's from chlorinated pesticides. At a recent meeting, sponsored by the pwqa's National Water Quality Lab oratory, Duluth, Minn., a general pro cedure was recommended for separa tion of pea's from pesticides. In this procedure for biosamples, the sample is extracted with hexane ns in regular pesticide analysts. It is then partitioned with acetonitrile to remove fain, the elenned-up extract is passed through a Fluorisil column and then through n silicic acid column. Finally, the sample is analyzed by gas chromatography, with a chloride-specific detector. In this way the pesticides are retained on the silicic acid column for later elution and identification. Research needs To assess fully the significance of pen's as environmental pollulants. ad ditional research is needed. No one really knows the extent of the chronic effects of these chlorinated hydrocar bon*. Some problems that need to be considered are: * Although Pen's are known to ac cumulate in human organs we do not know at what concentration they will begin to exhibit toxic effects. Will these chronic effects be similar to those shown in animals--microsomal en zyme activity, calcium metabolism in hibition, and so on? What are other possible chronic effects? Which of the many pcb com pounds in the commercially available mixtures are responsible for their tox icity? Can commercial pcx mixtures be modified to eliminate the toxic com ponents? Pure samples are required to answer these questions. At the present time work is continuing at the pwqa's Southeast Water Laboratory to sep arate each of the Aroclor mixtures into its many components, and to identify each component. * We need to know all the uses for the pcb's. What is the annual produc tion of pcb's? Our knowledge of these facts is limited and needs to be ex panded. These facts should be known if we are to accurately determine how they get into the environment, end take steps to prevent further environmental contamination by them. In view of the complexity of the isolation and accurate quantitative analysis of pcb'* in chlorinated resi dues, a straightforward, unambiguous measurement of them needs to be de veloped. MQNS 087339 * What is the fate of pcb's in net* ural waters7 More needs to be know* of their partition coefficients between bottom sediments and water. This is vital if we are to estimate how loag it will take for a river bed to clean itself of contamination, ft will also be useful when assessing the effects of Pea's on marine life that feed on the bottoms of lakes, rivers, and estuaries. We should also learn more about pcb solubility In water of various ionic strengths. Are present waste treatment sya* teim adequate to handle pcb's? Do spe cial measures need to be taken when pen's are part of the waste effluent be ing treated? By trying to get some of these an swers now, we may And that we are in a position to control the escape of pi n's into the environment before ad ditional damage is done. So frequently, action is taken only after it is evident that massive damage has resulted from a particular pollutant. In the ease of the pen's we may have an opportunity to resolve the situation before that happens. Additional Readfcig Hubbard, H. L, "Chlorinated Biphenyl and Related Compounds," Encyclo pedia of Chemical Technology, 2nd ed., S, Interscienee PuM., New York, NY, 1964. pp. 289-290. Reynolds, l. M,, Buff. Environ. Content. Toxicol. 4.128 (1989). Rtsebrough, R. N., et. af.. Nature 279 (I960). Carl C. Gustafson, chairman of the Department of Chemistry of King's College. Briarciiff Marior, NY. r#. ceiveti a Ph.D. in organic chemistry from the University of Delaware in 1957. During the 1969-70 academic year, he was on leave at the pwqa Southeast Water Laboratory in Athens, On., where he studied trace organic analysis in waste effluents. As a mem her of the National Water Contami mints Characterization Research Pro gram, he worked with pen'j and pulp and paper mill effluents. Volume 4, Number 10, October ISTB IIP