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About Acrylonitrile | The NCI Study | The Oxford The NCI Study Early studies (1970 - 1980's) were inconclusive about whether or not AN caused cancer in humans. However, these studies did show evidence of increased cancers of the brain and ear duct in rats. The animal studies were used as the basis for rating AN as a probable human carcinogen. In the early 1980's, the National Cancer Institute (NCI) agreed to a request by acrylonitrile manufacturers to conduct a definitive, high quality health study of workers exposed to acrylonitrile. The NCI coordinates the U.S. government's cancer research program, and is the largest of the 17 biomedical research institutes and centers at the National Institutes of Health in Washington, DC. The 10-year, $20 million NCI study examined 25,460 workers employed in eight U.S. plants from the 1950's through 1983. Companies involved were Monsanto, Cytec, Sterling Chemicals, Bayer and BP Chemicals. Information on all deaths due to cancer and other causes was collected through 1989. The study found no evidence of an overall increased risk for cancer death or any other cause of death. No increase was observed for leukemia, lymphoma, or cancers of the stomach, brain, breast or prostate, which were types of cancer previously associated with animal studies. Deaths from lung cancer among acrylonitrile workers were lower than the overall U.S. mortality rates. However, compared to non-exposed workers, a 1.5 fold increased risk for lung cancer was seen among workers experiencing the highest levels of AN exposure. This excess occurred primarily among workers first exposed before 1960 when exposure levels were higher than today. Because lung cancer risk did not increase consistently with increasing exposure to AN, the NCI concluded that the study results "do not provide strong or consistent evidence for a causal association" between acrylonitrile and lung cancer. The Oxford Conference With the completion of the NCI study - as well as three other AN health studies in the UK, Netherlands and U.S. - a meeting was convened in Oxford, England in August, 1997 to assess the overall health data for AN. These four studies examined death rates of 34,686 workers at 24 plants throughout the world. The meeting was attended by the principal investigators for the major studies, other academics with special interest in occupational medicine, and representatives of regulatory bodies, industry groups and labor unions. It was generally agreed by those in attendance that there is insufficient evidence to conclude that exposure to acrylonitrile is associated with an increase in human cancer. In a review of the papers presented at the conference, Prof. David Coggon concluded: "Thus despite its carcinogenicity in animals, there is little evidence to suggest that acrylonitrile causes cancer in humans." About Acrylonitrile | The NCI Study | The Oxford |
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