Mortality from respiratory cancers (including lung cancer) among workers employed in formaldehyde industries

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Abstract
A joint study on effects of formaldehyde exposure in industrial populations by the National Cancer Institute and the Formaldehyde Institute, Inc. (Blair et al. [1986]: J Natl Cancer Inst 76: 1071–1084; Blair and Stewart [1989]: J Occup Med 31: 881, Blair et al. [1990]: Am J Ind Med 17:683–700) reported no significant elevation in risk ratios standardized to the general population. Using the same data as Blair et al., we compared more exposed to less exposed workers to compute relative risk for respiratory and lung cancers using a multivariate, log-linear model incorporating factors for job type (hourly vs. salaried), cumulative exposure (0.1–0.5, 0.5–2, 2 + vs. <0.1 ppm/years), length of exposure (1–5, 5–10, 10+ vs. <1 years), and age. Models were fit for all workers, all males, all workers less than 65 years of age, and for all males less than 65 years of age. Hourly workers have a significantly elevated relative risk when compared to salaried workers. While only high levels of cumulative exposure show a significant elevation in relative lung cancer risk, trend analyses of the coefficients of a log-linear model show a significant trend of increasing risk with increasing formaldehyde exposure. The significantly elevated respiratory and lung cancer risk for workers younger than 65 may indicate a shift of respiratory cancer mortality towards younger ages among those occupationally exposed to formaldehyde. Coupled with the recent report of the American Cyanamid Company's Cohort Mortality Study that finds a significantly elevated lung cancer risk related to formaldehyde exposure of greater than or equal to 0.2 ppm and with Blair et al.'s finding of an elevated lung cancer risk ratio, the conclusion of an association between lung cancer and occupational formaldehyde exposure seems well supported.