Document X7DXQ7Bx8K8JOEgj0QBpjrwZx

41-119 SCIENCE NEWS WKLY. 110.500 ( > | I OCT 24 1970 fS] ENVIRONMENT ffi o O Frrst DDT, now PCB The polychlorinated biphenyls (pen's), 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 dot 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 chlorine- tion, the Pen's are as toxic or more toxic thin dot. One experiment, for j example, established that a res with j 62 percent chlorine was almost twice ! as effective as dot 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- ; story birds (which have very high tissue ' concentrations of both chlorinated pesti- | cides and pen's) are thinned, leading to { high chick mortality and eventual ex* j Unction. The most recent evidence came this month from the work of Drs. Lawrence McCloskey and Richard Chesher, who exposed corals to chlori- naied pesticides and Pen's while they * were Tektite 2 aquanauts (SN: 10/10, | p. 296). pen's apparenUy act synerglsti- j cally with chlorinated pesticides and | enhance their effects, says Dr. Chesher. | One of the potentially most serious re- , suits of the work was the finding that I mixture of pen's and chlorinated pes ticides will reduce oxygen production by plants associated with the coral after a relatively brief exposure at one pert per million. In the meantime, Monsanto Co., the sole United States manufacture? of pen'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 tems where the pen's are completely enclosed and thus not likely to get into the environment. Rut, says Dr. Robert Ritebrough of the Univertity of California at Berkeley, a long-time foe of rca's: 'Tin not very optimistic. This electrical equipment is i 1 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." t And just how the pen's have entered j the environment--where they are now t ubiquitous, although there are greater amounts near industrial areas--is still unknown. But many of the uses before Monsanto's Aug. 30 restrictions clearly 1 were capable of releasing large amounts t into the environment. Among these uses: piastizers, coatings for paper and ' fabric, fire-retardent 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 i provide at least an indication of sources, ' says Dr. Risebrough. Pea's have been found, he says, in municipal sewage entering Lake Michigan and in Call ! fomla. Further work may allow re ! searchers to team just how the pen's j enter the sewage. : Hampering the work haa been ; Monsanto's reluctance to cooperate, ; claims Rep. William F. Ryan (D-N.Y.) ` a crusader against pen's. Ryan says Monsanto has refused to provide him : with a list of all uses, claiming this : "would serve no useful nonpolitical I purpose." And Dr. Risebrough says | Monsanto also has refused to provide : statistics on amounts of Pen's manufac' hired. A Monsanto spokesman admitted : both charges this week, saying secrecy was necessary because Monsanto is the sole producer of pen's. The pen's have unique advantages I industrially because of their chemical ; stability. This stability is called persist[ ence, however, in substances such as S pen's and chlorinated pesticides that do | not degrade in the environment and thus are concentrated in food chains. I Says Dr. Risebrough: Badly needed are | programs for assessing the environment ; tal impacts of new commercial sub- i stances before they become so widely > used that we are economically depend- j cot upon them. i DRUG CONTROL HONS 032385