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i Health & Environment A publication of the Freshwater Foundation t\*uurinn information from its Health & Enrironmenl Xelunrk ... ... _ Volume 2, No. 7 _ August 1988 r v Feature Article Polychlorinated Biphenyls: How Do They Affect Human Health? Until 1971, polychlorinated biphenyls (PCBs) were different composition from commercial products. Most used commercially in the U.S. in capacitors and trans are similar, but not identical to Aroclor 1254. formers, carbonless copying paper, paints, and hydraulic. fluid. While many countries have since restricted PCB _ Studies in laboratory animal* _ - use, the compounds are still found in old transformers, a-z. To learn how PCBs might affect health, investigators capacitors, and other products.- - ---- . have studied PCB exposure' experimentally in animals PCBs are a group of 209 stable, fat-soluble chemicals. and in humans occupationally or accidentally exposed to Not easily broken down, they have accumulated in fish. . the compounds. from polluted waterways, in wildlife, and in human _.. Except for feeding studies in mink, which used PCB- " Vl organs, fatty tissue, blood; and milk. In the late 1960s - --^~and early-7Qs. PCBs were also detected in mcit, polluted fish, most animal studies have tested commer' dal products. Results show that the toxicity of commer- milk. andTcrcaL Today; however, bccuise of regulatoryr__ I dal mixtures varies. Mixtures like Aroclor 1260, with a Z2EC; restrictions and other measures,1 polluted fish are the '~f' . high degree of chlorination^ produce liver cancer in rats. primary food source of PCBs for humans. r: ' Mixtures with much less chlorination, on the other hand, Because they are fat soluble, PCBs tend to concen- - yidd a much lower cancer inddence, with a tumor trate in fatty tissue, and to a great extent, PCB levels in incidence similar to that in unexposed rats. Most tests different organs depend on the organs' fat content. Thus, have not demonstrated any mutagenic properties for in humans, fatty tissues contain the highest PCB concen- PCBs. nations. In fish, the highest levels are found in body fat Other adverse effects observed in different animal and the hepato-pancreas, not the edible portion. spedes vary. While all mixtures and congeners* tested Aroclor is the commercial name for the American induce mixed-function oxidases in the liver, the type of product of PCB mixtures. Different mixtures are further enzymes induced varies. PCB isomers that appear more identified by codes, such as 1242, 1016, 1254, that - toxic and that are retained longer in the body seem to designate the percent of chlorination of the mixture.... - - induce aryl hydrocarbon hydroxylase. Liver enlargement Because the time necessary for different components of seems to accompany enzyme induction. In some species PCB mixtures to break down in the environment varies, fed high doses of PCBs, investigators have observed liver PCB mixtures found in soils, sediments, and biota have a cell necrosis and fat accumulation in liver cells. Editorial Board Richard H. Adamson, Ph_D. Director Division of Cancer Etiology National Institutes o! Health National Cancor Institute Henry A. Andanan. hLO. Qua* ' Smnronmemat and Qironic Dianas* Sotacmdogy Wisconsai Dtviadi of Hoarm John Doufl. fcLD. ftuD. Daoarenam of Pna/macoiogy University of Kansas Madieat Camar Yemen N. Houk. WLO. Ovactor Cantar lot Environments! Haann Camara tar Oisaasa Comret Barbara S. Hubs. M.O. WJ>.H. Chav Dtoafimam of Eoidamioiogy Scneot of PvoHc Haaitn Univtrady of Nortn Carolaia Renata Kbnhrough, MA Diractor Haann and Risk Csoioaitras . Ofhe* of tna Aommstraior Eimronmantsl Protection Aganey RoWI W. Leader. D.V.M. Department of Pathology Mietugan Ststa Unvarauy Richard X Levina, MJ). M.P.H. Dtractor Department of Eoidamioiogy Chemical Induatry Instiluia of Toxieoiogy Jack SL MandaL Ph-D. Environmental and Occupational Haann School of Puefie Haann Univanity of Mrrmtsota Raymond R. Neutn. U.D. Di. P.H. Oval Esraatnotegicif Sludias Surname* Section Caktemia Oaotrunam of Haaitn Victor W. SldaL MA Protassor of Social Madicina Uomthorv Mcdtaal Camar Ataait Etastam Cokaga 01 Madicina Arthur C. Upton, M.D. Director Insthut* of Environmental Madtain* Haw York University Medical Camar Barbara Scott Murdock Editor Paula X Ripley . General Manager DSW 189806 ONE STLCOPCB4042106 by Restate D. Kimbrough, MX). CX. Environment cal Protection Agency, Office of Regional Op<~.acions. Director, Health & Risk Capabilities Chlorinated dibenzofurans may be responsi ble for the health effects attributed to PCBs. Rhesus monkeys exposed to technical " Even workers with exposures two orders PCBs have developed hyperplasia, or over- of magnitude greater than environmental' growth, of the epithelium of the gastric exposures seem to show no convincing ' mucosa. In rats, investigators have observed . . chronic health effects. In a number of capaci-" cell transformation, noting that hepatic cells tor plants, workers developed chloracne, a - transformed into pancreatic cells. This effect . persistent skin disease that primarily affects on cell differentiation, apparently modified bv hair follicles. Whether the chloracne resulted the epithelial growth factor, is more pro- - from PCB exposure or from exposure to nounced in rats exposed to Aroclor 1254. - chlorinated dibenzofurans, a known cause of Because the mixtures tested may have been - . chloracne and a possible contaminant of the ' contaminated with chlorinated dibenzofurans, PCBs, is unclear. There is reason to believe - such contamination may have contributed to ' that chloracne and other health effects popu- ' ' the toxic effects and be partly responsible for larly associated with PCBs are really caused by the variation in effects seen bcrwcen.mixtur.es ' chlorinated dibenzofurans. and between animal species. . In 1966 in Japan and in 1978-79 in In experimental animals, some mixtures Taiwan, two poisoning outbreaks took place affect reproduction more than others, but all - in people who accidentally ate rice oil con effects have been fctotoxic. In minks and taminated with a mixture of PCBs and poly monkeys, investigators have noted sponta;.. chlorinated dibenzofurans. The poisoning, . neous abortions; in rodents, they"have seen .; ` called Yusho disease in Japan and Yu-cheng - resorpuons. Exposure to lower doses may - disease in Taiwan, led to chloracne and dark reduce the weight of the offspring. No one ; discolored skin among most of those exposed. has reported malformations after exposure to - Children were bom with erupted teeth, and PCBs. Finally,' some species, such as monkey' dentition of the permanent teeth was affected. and mink, are muefa more susceptible to the-;-. Further, these people had many other acute toxic effects of these chemicals than rats'or mice.1" ' i ' - .' health effects, such as abnormal liver and nerve function tests, abnormal menses, and persistent bronchitis. Babies were bom with Effects on human health ... dark skin discoloration and low' birth weight Thus far, no conclusive adverse effects for term infants. In both episodes, later inves- . have been demonstrated in people who cam' ligation established chlorinated dibenzofurans ------ ..... A* chlorinated dibenzofuran=rricwi^s*rt5' as the cause of poisoning. . One reason for this conclusion is that U.S. workers exposed to much higher PCB doses than patients with Yusho and Yu-cheng dis ease do not show the same health effects. Some workers complained of burning eyes, nose, and throat. Some studies reported abnormal liver function tests. One srudv, in a capacitor plant, noted abnormal lung function tests among the workers. However, these workers had also had other exposures that could have resulted in abnormal lung-function tests.-' Attempts to conclusively demonstrate health effects in populations that cat fish from body burdens of PCBs from environmental exposure to trace amounts of PCBs. Such polluted waterways have generally failed. ' Occasional reports have noted behavioral ^ exposure is much less than that received by workers who made transformers or capacitors from the 1940s through the 1970s. changes and shorter pregnancies with higher fish consumption or higher intake of PCBs.'-' However, because these studies couldn't rule DSW 189807 STLCOPCB4042107 out other causes, the significance of their findings is unclear. . Several occupational studies have pre sented no conclusive scientific evidence that PCBs have caused cancer in humans.-" While one study found a positive association - between PCB blood levels and high blood pressure,'" the association appears spurious. * The levels of PC3s in serum are primarily a function of the amount of fat present in scrum. Serum PCB levels are, for instance, positively correlated with blood cholesterol levels.6-* The associations disappear when PCB levels are expressed as a function of fat in serum nuher than as whole serum. In popula tions on Western diets, both scrum fat levels and whole scrum PCB levels increase with age. They are usually higher in males than in females, which corresponds with population survey findings that females usually have lower cholesterol levels than males in the same age group. Finally, the prevalence of elevated blood pressure also increases with age. In essence, all the associations go in tandem and appear to be spurious. Thus, despite positive laboratory animal data and except for chloracnc, exposure to PCBs has led to no convincing, clinically demonstrable, chronic health effects in humans. *Mnhen of (he same chemical family; each member differs in (he number or location of substituents. References: 1. Kim bntugb el aL. Environ Health Prop. 24:174 184. 1078: 2. Kim- bmugb tt aL. Environ Health Prop. 59: J106. 1085; J. Kimbmugb tl aL. Ann. Rev. Pharmocol. Toxicol. 27:87-111. I<JB7; -1. Jacobson el at.. Div. Psychol. 20:523-532. 1084; 5. Fein el al.. J. Pediatr. 102:315-320. 1084; 6. Krtist tl al.. ). Am. Med. Assoc. 245 -.2505-2500. 1081; 7. Lawton el aL. Envi* ran. Health Pcrsp. 60:165-184. 1085. ... .Commentary Harnessing Natural Processes To Degrade PCBs. by Michael A. Kamrin, Ph.D~, Professor, Center for Environmen tal Toxicology, Michigan State University As numerous analyses of air, water, sediments, wildlife, and other environmental samples have shown. PCBs are extremely persistent com pounds found in all parts of the environment. ' In ambient air and water, PCB levels are quite low. Even if one assumes a lifetime exposure to the highest measured levels all day every day, air and water offer a low risk of human exposure. Fish, however, appear to be a more significant source of PCBs. Why? First, PCBs bioaccu mulate and biomagnify in the aquatic food chain. Further, as many people become more health conscious, they rend to eat more fish. For people who subsist almost entirely on fish they catch themselves, high environmental levels plus high consumption can lead to significant exposure. - - Because fish are such an impor tant source of PCBs, government agencies have taken steps to minimize this exposure. On the federal level, the Food and Drug Administration has set maximum tolerance levels for PCBs in fish sold in interstate com- raerce. To address intrastate consump tion. some states publish fish advisories that recommend limited or no consumption of fish from bodies of water significantly contaminated with PCBs and other chemicals of concern. A number of sates border ing Lake Michigan have collaborated on a common advisory for Lake Mich igan fish. PCB reservoirs Limiting exposure by regulation or recommendation does not address the fundamental reservoirs of expo sure--where PCBs are stored in the environment. Available data clearly indicate that the main sources of PCBs in fish are the sediments in contaminated rivers, lakes, streams, and estuaries. About one-third of all PCBs in the global environment are contained in fresh and saltwater sediments. Most remaining environmental PCBs seem to be stored in open waters around the world, largely as a result of atmospheric transport and deposition. Despite worldwide disper sal, however, studies of oceanic life suggest that PCBs are not evenly dis tributed: the highest levels are in the northern hemisphere, especially at lat itudes that encompass the industrial nations. In addition to the large quantin' of PCBs in the environment, an approximately equal amount is still in use, mainly in dielectric fluids in sealed electrical equipment. The most important step for limiting future exposure entails exercising great care in disposing of all PCB-containing materials still in service. In most cases, users of electrical equipment are taking care; continued vigilance DSW 189808 THREE STLCOPCB4042108