Acrylonitrile and cancer: a review of the epidemiology.

Several retrospective cohort epidemiology studies evaluated a number of health outcomes in workers exposed to acrylonitrile (AN). The epidemiology studies included in this review have been published since 1970 and were identified through Ovid and MEDLINE retrieval services using search words "acrylonitrile and cancer". We identified 26 studies which examined mortality and/or incidence rates among persons with AN exposure. Where cohorts have been updated the most recent data were relied upon but descriptions of the earlier publications are provided for background and rationale. Results are provided for all causes of death and all cancers. Detailed results and discussions are provided for the cancers which have received the most attention and for which some positive results have been reported. These include lung, bladder, prostate, and central nervous system cancers. In this review the four most informative cohort studies are evaluated and it is apparent that the results do not support a causal relationship between AN and all cancers or any specific type of cancer. IARC actually downgraded acrylonitrile from "probably carcinogenic" to "possibly carcinogenic to humans" finding that "the earlier indications of an increased risk among workers exposed to acrylonitrile were not confirmed by the recent, more informative studies". This was one of few downgrades of classification by IARC. Our review of the epidemiology data is consistent with the conclusions of the earlier IARC review which found no consistent findings of increased cancer risk across studies.