Reanalysis of lung cancer mortality in a National Cancer Institute Study on "Mortality among industrial workers exposed to formaldehyde".

The analysis of an historical cohort study of mortality among individuals occupationally exposed to formaldehyde by Blair et al. (2) in 1986 failed to allow properly for the Healthy Worker Effect and to evaluate time integrated exposure and length of exposure simultaneously. In our reanalysis of the same data we find a risk for lung cancer, increasing with increasing cumulative exposure to formaldehyde.