[Occupational exposure to formaldehyde and risk of cancer].

Formaldehyde is a widespread animal carcinogen with limited evidence of carcinogenesis in humans. We investigated the occupational risk of cancer (1970-84) among men and women in Denmark. Relative risks (RR) were estimated from standardized proportionate incidence ratios among patients whose longest employment had been held since 1964, at least 10 years before diagnosis, in 265 companies in which exposure to formaldehyde was identified. The only biologically plausible increased risk was for nasal cancer, for which relative risks of 2.3 (95% confidence interval = 1.3-4.0) and 2.4 (0.6-6.0) appeared for men and women, respectively. In the subgroup of blue-collar men with no probable exposure to wood-dust, the major confounder, the relative risk for this cancer was 3.0 (1.4-5.7). It is concluded that occupational exposure to formaldehyde may increase the risk of nasal cancer, but formaldehyde does probably not affect other cancers.