Introduction An International Agency for Research on Cancer (IARC) evaluated that the TDI was possibly carcinogenic to humans (Group 2B) based on inadequate evidence in humans and sufficient evidence in experimental animals. However after the IARC review, some epidemiologic study suggested that TDI was related to the cancer occurrence, especially lung cancer. So we analysed the cancer mortality of methanol exposed male workers in Korea.

Methods A cohort was comprised of 10,526 TDI exposed workers working between January 1, 2000, and December 31, 2004. These cohort members were matched with the mortality data of the Korean National Statistical Office to follow-up for cancer mortality between 2000 and 2011. Standardised Mortality Ratios (SMRs) of methanol exposed workers with reference to Korean men were calculated. Also controlling age, calendar year and other carcinogen exposure including hepatitis B and C, the Adjusted Hazard Ratios (AHRs) of workers categorised by the TDI-exposure duration (over 10 years) with reference to workers with less than 10 years were calculated.

Result There were no significantly increased or decreased SMRs. But, non-significantly increased SMRs were observed in lung cancer (SMR=1.11, 95% CI: 0.41 to 2.41) with over 10 years exposure. There were no significantly increased or decreased AHRs of cancer mortalities in workers exposed to TDI with over 10 years exposure compared to workers with less than 10 years.

Discussion In this study short follow-up periods and healthy worker effect (HWE) may hamper observation for increasing cancer mortality of TDI exposed workers comparing to that of Korean male. Continuous follow-up to overcome HWE and cancer morbidity study are needed to confirm this study result.