Abstract
The question of whether aromatic amine exposures can cause esophageal cancer was briefly discussed. Previous studies have shown that aniline dye production workers who had been exposed to benzidine (92875) and 2-naphthylamine (91598) experienced excess risks for esophageal cancer, with standardized incidence ratios of 203 to 348 and standardized mortality ratios of 228 to 388. None of the studies controlled for cigarette smoking and alcohol consumption. It was noted that since these risk factors also existed in the reference populations, only a large difference in smoking and drinking habits between the exposed and control populations could explain the excess esophageal cancer risk in the exposed groups. It is also possible that other exposures at the study worksites could account for the excess esophageal cancer risk although the risk did not appear to be related to occupational factors such as duration of total employment or time since first employment. Since aromatic amines, in order to be able to express carcinogenicity, must first be metabolized and activated in the liver, it is not immediately obvious why the esophagus would be a target organ. There is some evidence that cytochrome-P-4501A2 activity exists in the nasal pharynx of some animals, suggesting that carcinogenic aromatic amines could be activated in the upper aerodigestive tract of humans. This possibility should be investigated further. It appears, nevertheless, that most epidemiological studies of workers exposed to aromatic amines have generally not found an excess risk for esophageal cancer.
