Document 7180bZpvZZ52MEr6Dk42YzKe8

February 16, 1970 Mr. Harold R. Hoyle Biochemical Research Laboratory Dow Chemical Company 1701 Building Midland, Michigan 46640 Dear Harold 1 Although we have developed a tremendous effort in the last year-and-one-half concerning the polychlorinated biphenyl Interferences In pesticide residue analysis, I have not found any data that would lndlcats a change In the TLV's for the 42 and 54jf ohlorlnated materials. Z think Z have In hand everything that has been pub lished on the FOB-DOT situation and, although there have been references to toxicity studies underway, the latter relate to fish and birds principally. We have supplied samples to several FDA, FWFCA, Fish and Wildlife Service Laboratories, NAPCA, eto. and know that only two FDA laboratories are doing straight mammalian toxlolty work. We have two-year ohronlo studies underway at C91andra's using rats and dots and a three generation rat repro duction experiment In progress. At the moment Z don't foresee that the results of these studies should lead to the reduction of TLV's for Industrial workers. The way things are going In the whole field of environmental oontrol, Z won't presume to make any suoh statement as a flat prediction. Developments In the hext six months to a year will have a tremendous effect on the relation ship of toxlolty In any living species and exposures to humans. Best personal regards. Sincerely, XFWiJu Bluer F. Wheeler, Manager, Environmental Health MONS 090212