AROMATIC-AMINES AND CANCER

Epidemiological evidence on the relation between aromatic amines and c ancer risk is reviewed. In particular, cancer risk in humans resulting from exposure to aromatic amines from occupational sources and tobacc o smoking is assessed with reference to ecologic, cohort, and case-con trol studies. Seven arylamines have been classified by the Internation al Agency for Research on Cancer:benzidine-based dyes and MOCA (4,4'-m ethylene bis 2-chloroaniline) were considered 'probably' carcinogenic, Group 2A, because of a high level of evidence in experimental animals ; two occupational chemicals (2-naphthylamine and benzidine), one drug (Chlornaphazine), and two manufacturing processes (manufacture of aur amine and magenta) were included in Group 1 on the basis of 'sufficien t' evidence of carcinogenicity in humans. Occupational exposures to ar omatic amines explain up to 25 percent of bladder cancers in some area s of Western countries; these estimates might be higher in limited are as of developing countries. Aromatic amines contaminate the ambient ai r as a component of environmental tobacco smoke. There is increasing e vidence that the excess of bladder cancer in smokers is attributable t o aromatic amines rather than to other contaminants of tobacco smoke s uch as polycyclic aromatic hydrocarbons (PAH). A modulating role in th e risk of bladder cancer associated with exposure to aromatic amines i s played by metabolic polymorphisms, such as the N-acetyltransferase g enotype, raising important social and ethical issues. The consistent o bservation of a difference between men and women in bladder cancer ris k, after allowing for known risk factors, suggests consideration of ge nder-related biological determinants for future investigation.