Introduction An International Agency for Research on Cancer (IARC) Advisory Group recommended priorities for IARC Monographs during 2015–2019 in Lyon on April, 2014. They recommended methanol as medium priority of review. The background was three animal carcinogenicity studies. However there were no available studies of cancer in humans and has not been previously evaluated by IARC. So we analysed the cancer mortality of methanol exposed male workers in Korea.

Methods A cohort was comprised of 25 218 methanol 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 2 groups of methanol exposure level (10% to 50%, over 50% of TLV) with reference to workers with less than 10% were calculated.

Result There were no significantly increased SMRs. But, significantly decreased SMRs were observed overall cancer (SMR=0.70, 95% CI: 0.58 to 0.84) and liver cancer (SMR=0.68, 95% CI: 0.47 to 0.94). There were no significantly increased or decreased AHRs of cancer mortalities in workers exposed to methanol with 10%–50% of TLV and over 50% of TLV compared to workers with less than 10% of TLV.

Discussion In this study short follow-up periods and healthy worker effect (HWE) may hamper observation for increasing cancer mortality of methanol exposed workers comparing to that of Korean male. However based on no increased AHRs of workers with relatively higher level of methanol exposure, methanol might not be related to cancer development considering metabolic pathway different from ethanol. Continuous follow-up to overcome HWE and cancer morbidity study are needed to confirm this study result.

Acknowledgement This work was supported by Korea Environment Industry and Technology Institute (KEITI) through The Chemical Accident Prevention Technology Development Project funded by Korea Ministry of Environment (MOE)(2017001970001).