Cancer mortality in Korean workers occupationally exposed to methanol: a cohort study

Purpose: Recently, the international agency for research on cancer recommended that methanol should be recognized as a medium-priority, human cancer risk. Therefore, we performed an epidemiological study to evaluate the relationship between methanol exposure and the cancer mortality of Korean workers occupationally exposed to methanol.

Methods: The study cohort was composed of methanol-exposed 25,218 male workers, data on whom were available from the Korea Occupational Safety and Health Agency; all participants underwent methanol-associated medical check-ups at least once between January 2000 and December 2004. The durations of methanol exposure were categorized as < 10, 10-20, and ≥ 20 years. Workplace methanol exposure levels for each worker were divided into three grades. We compared their standardized cancer mortality rates (SMRs) to those of the general population. Intra-cohort hazard ratios were estimated using a Cox's proportional hazards model.

Results: We found no positive association between methanol exposure and cancer mortality. In terms of all cancer mortality, methanol-exposed workers exhibited significantly lower SMRs than the general population. In terms of other cancer mortality, no significant difference or trend was evident as a function of duration of methanol exposure.

Conclusions: Although we found no significant correlation between methanol exposure and cancer mortality, we believe the work is meaningful; this is the first, large-scale, human epidemiological study. The carcinogenic potential of methanol remains an open question, and studies with longer-term follow-up periods are needed.