PCBs, polychlorinated biI phenyls, may turn out to be as big a threat to the environment as DDT, the insecticide which has made headlines around the world because of its potentially damaging effects on the ecology. If so, the public fist will be shaken at industry instead of agriculture as in the case of pesticide pollution. This is because PCBs contaminating the environment come almost entirely from industrial sources. They are used in the manufacture of plastics, electrical producís, synthetic rubber, paper, automobiles, paints, waxes, printer's ink and adhesives, to name a few. Scientists at the Ann Arbor Great Lakes Research Laboratoryofthe U.S. Bureau of Commercial Fisheries are just now beginning an investigation of this persistent contaminant. Robert E. Reinert, who has headed the major research on the effects of insecticides on fishes and ether aquatic life in the Great Lakes for the federal ageney, says PCBs are just now "causing a good deal of concern." He points out that polychlorinted biphenyls are similar to DDT in their chemical characteristics. In o t h e r words they are not soluble in water and are thus taken up by fish and stored in their fatty tissue just as are the pesticides DDT and Dieldrin. Another problem is that these "highly rugged compounds" are so much like DDT in their chemical makeup that "they make pesticide analysis difficult," Reinert says. "The thing that concerns us about all these compounds in respect to fish are their sublethal, long-term effects on reproduction and growth as well as the possible effect on aquatic organisms in the food chain. "Some people think that just because there hasn't been any dieoff of fish in the Great Lakes attributable to LüDT or Dieldrin, we are rying wolf when there is no o real danger involved." But the fact these compounds prevent fish eggs írom hatching, thus curtailing reproduction and apparently causes the death of newly hatched fish, makes them just as damaging in the long run, or even more so, than if they killed large numbers of adult fish outright, he says. The first indication of PCB contamination of the environment carne in 1966 with a report by Soren Jensen, a Swedish scientist, that he had found the compound in the bodies of 200 pike taken from waters in various parts of his country, as well as in other fish and an eagle. Dr. Jensen, at that time, also analyzed eagle feathers preserved in a museum, some of them dating as far back as 1880, and found that the first feathers containing PCB were collected in 1944. Scientists in Great Britain and The Netherlands have more recently identified PCBs in wildlife in their respective countries. PCBs were first detected in North American wildlife when in 1967 when Monte Kirven of the San Diego Natural History Museum who was searching the southwest f o r the fast-disappearing peregrine falcon, found a nest of this bird of prey with a single, unhatched egg. Later, in analyzing the egg at a University of California at Berkeley laboratory, scientists found it contained PCB as well as DDT and DDE compounds. The evidence of PCBs in fish and wildlife in various parts of the world has since continued to mount. Concentrations in birds have been reported very high, such as up to 1,980 parts per million in body fat of North ■ can peregrine falcons and I 17,000 parts per million in the fat of the white-tailed eagle in Sweden. While much is not yet I known about this new source I of pollution, the distribution I of these compounds appears to be highest in áreas of high population density and I trial activity. This makes the I Great Lakes particularly I nerable to PCB I tion. II Like DDT, the polychlorinated biphenyls can be carried by air currents. Among possible sources of pollution which scientists have suggested for investigation are stacks of planta which manufacture Aroclor and those manufacturing products containing Aroclor. Other forms of industrial waste and particularly the mixing of PCBS and other synthetics and oil to make fire-resistant hydraulic fluid need investigation. One major oil company has stated that "industry wastes almost four times as much hydraulic oil as it uses." Another possible source is gradual wear and weathering of Aroclor-containing products which may result in slow release of PCBs as vapor or particulate matter into the atmosphere. This includes the constant friction on asphalt paving. Products containing PCBs may wind up in the city dump where burning at high temperatures may release PCB compounds as vapors. PCBs have not yet been detected in ! samples of airborne particulates, but have been shown to be present in rainwater. There is as yet no evidence to indícate PCBs in the ■ ronment are likely to reach levéis which would cause severe injury or death from short-term exposure. As with I DDT, however, the long-term, low-level danger may be just ( as devastating to our natural resources, and a threat to man himself. Scientists at Utah State University investigated the effect ' of a series of 10 PCBs ranging from 21 to 68 per cent chlorine on female rats. All of the PCBs stimulated enzyme induction, with the a m o u n t of stimulation increased in proportion to the amount of chlorine. PCBs containing more than 50 per cent chlorine were as potent in enzyme induction as DDT, the researchers discovered. Very little data is available on PCBs in humans, but both Swedish and British scientists have reported finding them in samples of human fat. In the U.S. they were found in human milk samples at Colorado College, Berkeley and Los Angeles, Calif. DDT content in mother's milk has been reported above the maximum concentrations permitted in cow's milk in some cases. The B PCB concentration in mother's milk in Berkeley and Los Angeles averaged about .06 parts per - million. It is not known how much PCB in humans is derived from food or how much may be absorbed from the air through breathing, but concentrations in fish are probably the highest among foods eaten by humans. Reinert notes in his recent paper "Pesticide Concentrations in Great Lakes Fish," V that the U.S. Food and Drug Administration has established temporary tolerance levéis for fish shipped acruss state borders of 0.3 parts per million of Dieldnn and five parts per million of DDT. No tolerance levéis for PCB in food have been established. White not much is known about PCB concentrations in Great Lakes fishes, considerable is known about DDT and Dieldrin levéis, thanks to Reinert and his co-workers. In testing thousands of Great Lakes fish at the Ann Arbor laboratory since 1945, Reinert this year reported the following averages for various species of fish in Lake Michigan on a whole fish basis: Alewife, 3.89 parts 'per million of DDT and 0.11 parts per million of Dieldrin; smelt, 2.31 parts per million of DDT and .06 parts per million of Dieldrin; lake herring, 6.7 parts per million of DDT and .20 parts per million of Dieldrin; and yellow perch, 3.22 parts per million of DDT, and .08 parts per million of Dieldrin. As for the lake's two most sought-after fish, coho salmón and lake trout, coho collected in the spring in the southern end of the lake averaged 3.51 parts per million of DDT and .11 parts per million of Dieldrin. Coho taken in the fall in the Platte River, however, averaged 12.21 parts per million of DDT and .14 parts per million of Dieldrin. DDT concentrations in the steaks of the Platte River fish averaged 14.89 parts per million. Lake trout from Lake Michigan had concentrations averaging from .89 parts per million of DDT for smaE fish to 6.96 for large fish. "Small lake trout from the southern Lake Michigan, but Reinert end of the lake had higher DDT and Dieldrin concentrations than fish of the same size from the northern portion." No large lake trout were collected from southern estimates that large trout in that portion of the lake could have concentrations as high or higher than 20 to 30 parts per million of DDT on a comparative basis. Fish from the other four Great Lakes had lower concentrations of the two insecticides, with those from Lake Hurón, Lake Ontario and Lake Erie averaging about half that in Lake Michigan fishes, and those in Lake Superior being the lowest in most cases. In any case, Reinert reports, "labora tory experiments indícate that fish can build up concentrations of DDT and Die1drin at the parts-per-million level from parts-per-trillion concentrations in water." The U.S. Bureau of Commercial Fisheries biologist points out that "the blame for the contamination of the Great Lakes cannot be placed on any , single organization, agency or municipality. All are to some degree responsible- in fact, all users of insecticides over the past 20 years have contributed to the present concentration in the Great Lakes." The reason Lake Michigan has higher concentrations of the insecticides than the other Great Lakes is not only because of the more extensive orchards along its shores and its many tributary streams which bring them in from a variety of uses, but also its average water retention time of 30.8 years. Unlike the other Great Lakes where water retention time is much less, Lake Michigan presently contains some water which was in it even before chlorinated 1 bon insecticides were first used in the 1940's. Since scientists have shown I that these insecticides I ly affect fish reproduction in I high concentrations, Reinert notes that "the amounts of I DDT and Dieldrin in Lake Michigan fish and eggs, I fore, are close to the level that I could adversely affect I duction." What he and his co-vvorkers will find out about the effects of PCBs remains to be seen I - but from all indications they I could pose as grave a threat. I The letters PCB may come into nation-wide household use as have the letters DDT. Since I the chemical composition is I so similar they could both I erate the same fear for the future of our natural sources.
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