Cohort mortality study of garment industry workers exposed to formaldehyde: Update and internal comparisons

Background To further evaluate the association between formaldehyde and leukemia, we extended follow-up through 2008 for a cohort mortality study of 11,043 US formaldehyde-exposed garment workers. Methods We computed standardized mortality ratios and standardized rate ratios stratified by year of first exposure, exposure duration, and time since first exposure. Associations between exposure duration and rates of leukemia and myeloid leukemia were further examined using Poisson regression models. Results Compared to the US population, myeloid leukemia mortality was elevated but overall leukemia mortality was not. In internal analyses, overall leukemia mortality increased with increasing exposure duration and this trend was statistically significant. Conclusions We continue to see limited evidence of an association between formaldehyde and leukemia. However, the extended follow-up did not strengthen previously observed associations. In addition to continued epidemiologic research, we recommend further research to evaluate the biological plausibility of a causal relation between formaldehyde and leukemia. Am. J. Ind. Med. 56:1027-1039, 2013. (c) 2013 Wiley Periodicals, Inc.