Document NGzwdN2NvXjn0eOM7jNy25JyR

181 DDT Peril THE OREGONIAN, THURSDAY, AUGUST 21, 1969 By RICHARD FLOYD Staff Writer, The Oregonian ; CORVALLIS (Special) -- Persistent pesticides, includ- ing DDT, made some points ; Wednesday at a pesticides : symposium at Oregon State University, "Data now available indi cate that as long as pesticide residues remain at the present level, they are not considered hazardous to human health," said Dr, William F. Durham, ; chief cf the Parrine Primate : Research Branch Public '-lealth Service, in Florida. "However, continued sur veillance and research on their effects are necessary to assure that subtle effects from . continued low-level exposure do not occur, and also to de tect possible harmful effects of new compounds." Durham said the present mean storage level of DDT materials is about 11 parts per million in this country's general population. ' "There has been no signifi cant increase in the storage of DDT in the general population of the U.S. since it was first measured in 1950." Another speaker, Dr. John E. Swift, chemical coordinator of the extension service of University of California at Berkeley told what happened in the San Joaquin Valley when substitutes for DDT were "Since 1963, because of DDT levels in milk, we put DDT and DDE, a breakdown product of it, on the restricted list and set up buffer zones for ; forage crops, virtually elimi nating DDT," Swift said. "By 1965, the DDT levels in milk had dropped and are still down, but the cotton crop is threatened and bee colonies vital to many of bur crops are being lost -- 83,000 colonies . last year." Swift announced during the final session of the OSU sym posium on the biological im pact of pesticides in the envi ronment, that California will further restrict DDT use Jan. 1, 1970. Tightly controlled, it| will be used only to protect com, bean, cotton, tomatoes, crops all subject to the same kind of worm. "We have substitutes for ' DDT, but all are stop-gap measures," Swift said. . Not all is sweetness and ' light about the more rapid breakdown compounds suggest ed as replacements for the per sistent (more stable) pesticide DDT, and other chlorinated hydrocarbons, said Donald G. Crosby, University of Califor nia at Davis. He called for a closer look at some of the substitutes for DDT. What if pest controls were eliminated? "It would mean 25 to 30 per cent reduction in crops and livestock in three to five years," said Kenneth Walker, assistant to the deputy admin- J istrator of the Federal Agri cultural Research Service. "About 70 per cent of crops in the U.S. could not be grown successfully without pesti cides." He said the complete ban ning of DDT or any chemical material would be an error. Summing up the symposium which opened Monday and at tracted 450 scientists from throughout the nation. Dr. Joseph C. Street, Utah State University, said: "The need for chemicals to retain our advantage over pests have been reaffirmed, but we have heard increasing evidence that residues of pesticides could have subtle effects in some organs of some populations. "The World Health Organi zation has said immediate dis continuation of use of DDT would be a disaster to world health. Which direction do we take? "There is no simplistic resolution." . DSW 433735 STLCOPCB4086843