Formaldehyde Exposure and Leukemia Risk
The association between formaldehyde exposure and leukemia risk remains contentious due to inconsistent epidemiological evidence and limited mechanistic support. Epidemiological studies are designed to uncover the relationship between exposure to a hazard and risk of a disease; positive findings provide strong supporting evidence for assigning a convincing causal link of the hazard and the risk. In the case of formaldehyde, two of three major human studies revealed an association between the aldehyde and the cancer, but the largest British study showed no link. In this chapter, all epidemiological studies beyond these major three were collected, reviewed, and a meta-analysis, a statistical tool to combine results across multiple studies to increase their power, was conducted. Briefly discussed in this chapter is the meta-analysis approach, selection of studies, results analysis, and a comparison with other previous meta-analyses. Using a literature-based approach with novel criteria, convincing evidence of increased leukemia risk in formaldehyde-exposed workers and professionals is presented. These findings support the IARC and NTP’s classification of formaldehyde as a human leukemogen and underscore the need for further investigation of the mechanisms of formaldehyde-associated leukemogenesis.