Formaldehyde and leukemia: an updated meta-analysis and evaluation of bias

Objective: Formaldehyde exposures are common, and data linking these exposures to leukemia have been mixed and controversial. The objective of this analysis is to review the current epidemiologic literature on formaldehyde and leukemia. Methods: We performed an updated meta-analysis focusing on high-exposure groups and myeloid leukemia and included two large recent studies: one involving 25,000 workers in US formaldehyde industries and the other involving a cohort of 13,000 funeral directors and embalmers. Results: Formaldehyde was associated with increased risks of leukemia (relative risk 1.53; 95% confidence interval 1.11 to 2.21; P 0.005; 14 studies), specifically myeloid leukemia (relative risk 2.47; 95% confidence interval 1.42 to 4.27; P 0.001; 4 studies). Conclusion: These findings provide evidence of increased myeloid leukemia risk with exposure to formaldehyde.