Document bBbv2RKDMbXKVDrKryZ4Q46n1

WBRARCH TOPIC* / Chemical Pollution: Polychlorinated Biphenyls Polychlorinated biphenyl* (PCBs) arc The major uses of PCBs derive from for PCBs within the environment, al , widely used industrial chemicals that their nonflammability, high dielectric though the atmosphere also appears to were never intended for release into the constant, and plasticizing abilities. These be a means of dispersal. Adel Saroflm environment, but they have nonetheless uses include applications as dielectric of the Massachusetts Institute of Tech been found in rainwater, in human tis fluids in capacitors and transformers, nology has estimated that from 1000 sue, and in many species of birds and as hydraulic fluids, and as heat transfer to 2000 tons per year escaped into the fish. How PCBs came to be widely fluids; also PCBs have been widely atmosphere in past years from plasti distributed in the environment and used as plasticizers and solvents in cized materials containing PCBs, and what biological effects they have are adhesives, sealants, paints, and printing that about 4000 tons per year entered still largely unknown. But like DDT, inks. Some 95 percent of the large waterways from dumping and leakage PCBs apparently degrade very slowly phase correction capacitors used in of lubricants, hydraulic fluids, and heat under natural conditions. They tend to transmitting electric power, for exam transfer fluids. Other sources may in accumulate in the food chain, and once ple, contain PCBs--amounting in 1968 clude leaching from dumps and land ingested, they are stored in the body's to almost 2.5 million gallons in the fills, where, Saroflm believes, about fatty tissues. As is true with many other United States alone"; replacement of half of the PCBs produced eventually chlorinated hydrocarbons, even small PCBs by other dielectric fluids, accord end up. Although measurements of J doses of PCBs can be toxic, although ing to Martin Broadhurst of the Na PCBs in air and water are scant, the it is not dear that the amounts found tional Bureau of Standards, would re general pattern from these measure in fish or birds have had detrimental quire that the capacitors be rebuilt and ments and from more extensive mea effects. The only epidemiological infor that they be 50 percent larger. Alter surements of PCB residues in biotas is mation about PCBs' effects on man nate materials for plasticizer applica consistent, according to Saroflm, with comes from an accidental poisoning tions of PCBs, on the other hand, are the hypothesis that discharge of PCBs incident in Japan in which some 1000 readily available. into the environment occurs mainly persons were affected. Industrial use of PCBs has grown near industrial areas. A similar pattern Polychlorinated biphenyls are rela steadily since their introduction in was found by Gilman Vcith of the Uni tively inert compounds that have low 1930. U.S. sales in 1970 came to about versity of Wisconsin in his studies of solubilities in water. The PCBs pro 34,000 tons, with cumulative produc Lake Michigan watersheds; he also de ; duced commercially arc mixtures, in tion over the years amounting to an tected PCBs in the sewage of all mu i corporal ing some 50 or more of the estimated 4 X 103 tons. (By compari nicipalities studied. 210 different PCB compounds that are son, U.S. production of DDT in recent Once in the environment, PCBs ap theoretically possible from chlorinating years has been about 70,000 tons.) pear to persist for a long time. Labora biphenyl. The most common industrial Less, in fact almost nothing, is known tory studies by O. Hutzinger of the mixtures average between 40 and 60 about the quantities produced world National Research Council of Canada percent chlorine content, but their iso wide; in addition to the production in in Halifax and others have indicated meric composition is only partially the United States, PCBs are made in that PCBs can be dechlorinated by known, thus complicating the problems Europe, Japan, and the U.S.S.R. The ultraviolet light Jtnd lead to the forma : of sampling and analysis. Gas chroma only U.S. producer of PCBs, the Mon tion of hydrtJxyl derivatives and other tographic techniques are now most santo Chemical Corporation, refused polarcompounds that are more readily commonly used to determine the pres until recently to release production fig degraded by microorganisms, but the ence and the amount of PCBs in a ures, *1 b* ut 'the company has taken the extent to which this occurs under nat sample. The method is not specific^ for unusual step of refusing to sell any ural conditions is not known. In many identifying particular PCB compounds more F*CBs for plasticizer applications areas, however, PCB residues in fish because of the lack of samples of the and those heat, transfer applications in are equivalent to or higher than DDT . different isomers as reference standards. volving food preparation. Current an and other pesticide residues. David There appears to be some variability in nual U.S. sales, as a result, have fallen Stalling of the Bureau of Sport Fish biological and chemical activities among to about 20,000 tons per year, although eries and Wildlife, Columbia, Missouri, the compounds; highly chlorinated exports have continued to increase; found PCB residues as much as 100 PCBs seem to persist in the environ How PCBs are released into the en times larger than DDT residues in fish ment the longest and are less toxic vironment is not known, but several from heavily industrialized areas, with than the more rapidly degraded low scientists believe that sewage outfalls roughly equal residues of both sub chlorine forms. There is also evidence and industrial disposal into waterways stances in fish from many other regions. that some commercial PCB mixtures, arc major sources. Rivers and streams The highest PCB residues in fish especially those manufactured in Eu may be the primary means of transport seem to occur in highly polluted coastal rope or Japan, may contain trace waters--like Tokyo Bay and Long Is . amounts of dibenzofurans or other ex * More detailed reference to many of the ttudtet mentioned here can he found in (he forthcoming land Sound--and in some inland water tremely toxic impurities, which may be mint! Unit of EMvfronHuntal Health Perspective** ways--such as the Great'Lakes--where the cause of some of the toxic effects ascribed to PCBs themselves. i journal to be peblttheU by the National Inui- tirtc of Environmental Health Sciences, Research Triangle Park, North Carolina. coho salmon have been found with PCB concentrations in excess of 5 parts u JANUARY irrj <1-117 SCENCE YtKLY. 161 r- DSW 332682 STLCOPCB4079258 \ per million, the limit at \ h the U.S. eggs with high PCB residues h. been PCB mixture, which Vos believes to be Food and Drug Administration attempts traced to contamination of the poultry dibenzofuran. to seize contaminated fish and poultry feed by leaking heat exchangers, ex The results of a 2-year study funded sold in interstate commerce. More cept in one instance where the source bj Monsantojhowed liver damage and typical concentrations, in most species of the PCBs remains undetermined. some difference in weight gain in rats of fish in the North Atlantic, range Residues are present in dairy milk in and dogs whose feed contained 100 from 0.01 to 1.0 ppm. Fish taken from some localities. ppm of PCBs, but no teratogenic or undisturbed arctic lakes have been Officials of the Food and Drug Ad mutagenic effects. At a dose rate of found to contain comparable residues. ministration characterize PCBs as a 10 ppm, there were apparently no ef Both surface-feeding fish and those "potential but not immediate health fects of any kind, except for some im that dwell at greater depths contain hazard," and claim, on the basis of pairment to the hatching of chicken PCBs. Even higher concentrations are their monitoring programs, that except eggs. Reproduction was affected most found in birds that feed on fish, reach for his eating of fish the American by low-chlorine PCB mixtures, - but ing 300 to 1000 ppm in cormorants consumer receives no systematic ex long-term damage to the liver seemed and ospreys. According to Robert Rise- posure to PCBs. However, FDA au to be due to high chlorine mixtures. By brough of the University of California's thority extends only to interstate sales contrast, in one of the field occurrences Bodega Marine Laboratory, residues of food, and FDA guidelines tend to of PCB contamination, the halchability i are generally highest in bird specimens reflect only the average consumer. It of eggs at Holly Farms in North Caro from the North Atlantic or from along seems likely, because of the localized lina was noticeably decreased, even the California coast, and generally nature of PCB sources and variations though the concentration of PCBs in lower in birds from the South Atlantic in individual diet, that heavy fish eaters the feed was less than the no-effect and Central Pacific Oceans. Residues and some other individuals experience levels reported in the Monsanto study. appear to be lowest in wildlife from the more substantia] exposures. Although most birds and mammals Antarctic region. The only clinical experience with appear to be relatively resistant to Most U.S. inhabitants apparently human illness that is directly trace PCBs, some species, such as mink, seem have some residues, if only traces, of able to PCB consumption occurred in to be more susceptible. Fish are also PCBs in their bodies. Preliminary data 1968 in southern Japan. More than more susceptible; Stallings found that from a nationwide monitoring program 1000 persons who had eaten rice oil bluegill and catfish died when exposed being coordinated by the Environ contaminated with PCBs that leaked for several weeks to concentrations be mental Protection Agency show that from a heat exchanger during manu tween 20 and 50 parts per billion, that 33 percent of more than 600 samples facture developed darkened skins, eye trout died at about 8 ppb, and that of human adipose tissue contained discharge, severe acne, and other symp lethal doses for shrimp were as low PCB residues of at least 1 ppm. One toms of what came to be called Yusho, as 1 ppb. individual, an old man wiih no known oil disease. Patients were found to have The biological actions of PCBs in industrial exposure to PCBs. was found consumed an average of 2 grams of side the body are also relatively un by the Michigan Department of Health PCB, with symptoms appearing at a known. PCBs have been show n to alter to have 100 ppm in his fatty tissues. minimum dose of about 0.5 g. The liver tissue, inhibit the growth of cul The source of PCB residues in hu PCBs can readily cross the placental tured cells, and affect a variety of cn- man tissue is presumably food. Studies barrier, and several infants were born zyme systems; but in most instances in Sweden have indicated that fish are with Yusho symptoms, some to ap the mechanism of action is still uncer the primary source of PCBs for most parently unaffected mothers. Recovery tain. Paul Lichtenstein of the Univer Swedes, with average intake of PCBs appears to be difficult, according to sity of Wisconsin has shown that PCBs from all sources estimated to be about Ma^anori Kuratsune of Kyushu Uni interact with DDT and other chlori I microgram per kilogram of body versity in Fukuoka, Japan, with symp nated pesticides; nontoxic amounts of weight per day. Individuals who ate toms still present in many cases 3 years PCBs in insects increased the toxicity large amounts of fish consumed about later; no methods of treatment are of DDT and some organo phosphate ten times as much PCBs. Babies re known. It is not clear whether any of pesticides by as much as 100 percent. ceived the highest doses per kilogram the subsequent deaths among the pa Much of the research on PCBs has of body weight, largely from milk. Resi tients can be attributed to acute PCB pointed to the similarity of PCBs and dues of PCBs in food were somewhat poisoning, and it is still not known DDT in their environmental effects. smaller than those of DDT and metabo whether the commercial PCB mixture They are both widely distributed in the lites of chlorinated pesticides. involved contained traces of dibenzo- environment, they both affect the re . In the United States, the pattern furans or other impurities. productive system of birds, and they appears to be the same, with PCBs Although PCBs have been in use for enter the human diet primarily through common in freshwater fish such as more than 30 years, detailed studies of residues in fish. But PCBs, unlike DDT, coho salmon and lake trout. Small their toxic properties have only recent were seldom deliberately released into DSW 332683 residues in cereals have been traced ly been undertaken. The studies are the environment. Their presence and to the recycled paper used in packag complicated by variability in the tox persistence there reemphasize the like ing and thence to the ink ip a brand,of icity of different commercial samples of lihood that any widely used industrial carbonless carbon paper, among other PCBs. Experiments in the Netherlands chemical may become an environmental sources. The ink no longer contains( by J. G. Vos of the University of pollutant, and increase the responsibil PCBs, and efforts are being made to Utrecht showed liver damage and ity for public disclosure of production separate out old stocks of the carbon redema in chickens and skin lesions in quantities and use patterns when similar paper in the manufacture of recycled rabbits. The worst effects seemed to be situations occur in the future. i paper. Several batches of poultry add IJ6 Caused by an impurity in the European \ --Allen L. Hammond SCIENCE, VOL. 175 STLCOPCB4079259