WASHINGTON (Dec. 18)—The Environmental Protection Agency has reclassified 1,3-butadiene, a major component in synthetic rubber, from "probable carcinogen" to "carcinogen." The agency issued a document Oct. 29 on the reclassification, basing its decision largely on a study of the health histories of 16,000 workers employed at styrene-butadiene rubber plants. But it isn't clear what effects, if any, the reclassification will have on the regulation of butadiene. "We haven't had a lot of time yet to digest it," said Jim McGraw, CEO and managing director of the International Institute of Synthetic Rubber Producers, about the dense, 430-page reclassification document. The EPA has closely regulated butadiene under the Clean Air Act since 1990.