As a result of the March 25, 1976 announcement by B. F. Goodrich Company of a possibility of an excess of leukemia among workers in a styrene-butadiene rubber plant, ARCO/Polymers, Inc., a subsidiary of Atlantic Richfield Company, voluntarily initiated an epidemiological study of workers at its ARCO/Polymers' Beaver Valley Plant. This plant produces styrene, polymeric products derived from styrene and styrene-butadiene lattices. As summarized in an October 14, 1977 letter from ARO/Polymers to NIOSH, a copy of which is attached, of the cohort of 4,300 employees in the study group, 516 are known to be deceased. Death certificates have been obtained for 444 of these. A report has not yet been made by a nosologist. A preliminary examination indicates that seven cases involved leukemia. A statistically significant analysis cannot be made until the nosologist's report has been received on at least 90 percent of the known cases of death. We are currently attempting to obtain the additional death certificates needed to attain this sample size.