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! 41-119 SCIENCE NEWS . WKLY. 110.500 . OCT 24 1970 (IS) i ] ENVIRONMENT O ' First DDT, now PCB The polychlorinated biphenyls (pcb's), a class of industrial compounds with !. a wide variety of uses, have been sus- - pected since 1966 of causing many of : the same ill effects in organisms as ddt . and other chlorinated pesticides. Grad- ; ually the evidence has accumulated, and now there is little doubt of their , danger (SN: 3/28, p. 321). ! Depending on the degree of chlorina tion, the pcb's are as toxic or more toxic than ddt. One experiment, for example, established that a pcb with 62 percent chlorine was almost twice as effective as ddt in breaking down the sex hormone estradiol in birds; this is regarded as the initial step in the mechanism by which egg shells of pred atory birds (which have very high tissue concentrations of both chlorinated pesti cides and pcb's) are thinned, leading to . high chick mortality and eventual ex tinction. The most recent evidence came this month from the work of Drs. Lawrence McCloskey and Richard Chesher, who exposed corals to chlori nated pesticides and pcb's while they were Tektite 2 aquanauts (SN: 10/10, p. 296). pcb's apparently act synergisti- cally with chlorinated pesticides and : enhance their effects, says Dr. Chesher. . One of the potentially most serious re sults of the work was the finding that a mixture of pcb's and chlorinated pes- ; ticides will reduce oxygen production i by plants associated with the coral after ! a relatively brief exposure at one part ! per million. * In the meantime, Monsanto Co., the ! sole United States manufacturer of ; pcb's, has greatly restricted the uses of : these compounds, claiming it is now recommending use only as insulating : fluids in electrical and heat transfer sys- ' terns where the pcb's are completely j enclosed and thus not likely to get into ' the environment. : But, says Dr. Robert Risebrough of i the University of California at Berkeley, a long-time foe of pcb's: "I'm not very . optimistic. This electrical equipment is fA. ! going to be thrown away eventually. : With an expanding technology, I am . afraid we will continue to have large : amounts of these chemicals entering the : environment.'' And just how the pcb's have entered the environment--where they are now ubiquitous, although there are greater ; amounts near industrial areas--is still unknown. But many of the uses before : Monsanto's Aug. 30 restrictions clearly were capable of releasing large amounts : into the environment. Among these uses: plastizers, coatings for paper and fabric, fire-retardant compounds, as phalt, adhesives, paraffins, printer's ink, rubber products, solvents for pesticides, lacquers, coatings for water-repellent canvas and as hydraulic fluids. Recent work, however, has begun to provide at least an indication of sources, , says Dr. Risebrough. pcb's have been ; found, he says, in municipal sewage entering Lake Michigan and in Cali- fomia. Further work may allow re searchers to learn just how the pcb's enter the sewage. ! Hampering the work has been ; Monsanto's reluctance to cooperate, claims Rep. William F. Ryan (D-N.Y.) ! a crusader against pcb's. Ryan says ; Monsanto has refused to provide him with a list of all uses, claiming this "would serve no useful nonpolitical .; purpose." And Dr. Risebrough says ; Monsanto also has refused to provide statistics on amounts of pcb's manufac tured. A Monsanto spokesman admitted : both charges this week, saying secrecy was necessary because Monsanto is the . sole producer of pcb's. 1 The pcb's have unique advantages : industrially because of their chemical ! stability. This stability is called persist ence, however, in substances such as ; pcb's and chlorinated pesticides that do ; not degrade in the environment and ; thus are concentrated in food chains. ! Says Dr. Risebrough: Badly needed are ! programs for assessing the environmen- ; tal impacts of new commercial sub- i stances before they become so widely ; used that we are economically depend ent upon them. I DRUG CONTROL DSW 552452 STLCOPCB4090869