The National Institute for Occupational Safety and Health (NIOSH) recommends that as a prudent measure, epichlorohydrin be handled in the workplace as if it were a human carcinogen. This recommendation is based primarily on two recent studies: a long term epidemiologic study showing significant increase in respiratory cancer deaths of exposed workers, and an inhalation study showing an increase in nasal carcinomas in rats. In addition, cytogenic studies of human peripheral lymphocytes have shown a highly significant increase in chromosome abnormalities in exposed workers. Pending further evaluation of its carcinogenic potential, NIOSH believes it would be prudent to minimize occupational exposure to epichlorohydrin. NIOSH has prepared this Bulletin to advise you of these recent studies, their implications for occupational health, and precautions for handling products containing epichlorohydrin. We request that producers, distributors, and users transmit this information to their customers and employees, and that professional associations and unions inform their members.