Metalworking fluid exposure and cancer risk in a retrospective cohort of female autoworkers

Abstract

Metalworking fluids (MWFs) have been associated with cancer of several sites, but the risks have been primarily examined in men or in studies that adjusted for gender in analyses. To evaluate whether risks were similar in women, we report cancer mortality risk among 4,825 female autoworkers within the united autoworkers-general motors autoworkers cohort. Standardized mortality rates (SMRs) were calculated based on Michigan death rates (1980-2004). Internal comparisons (1941-2004) were examined using Cox regression for straight, soluble, and synthetic MWFs, and their corresponding oil- and water-based fractions. MWF exposure levels in the female cohort were generally less than two-third the MWF levels in the male cohort. Female autoworkers had an excess of cancer from all sites (SMR, 1.10; 95 % confidence interval (CI), 0.98-1.22) and lung cancer (SMR, 2.08; 95 % CI, 1.71-2.52). Colon cancer risk increased with straight (mineral oil) MWF exposure (exposure > median; hazard ratio = 3.1; 95 % CI, 1.2-8.0). A protective effect was observed for ovarian cancer with the soluble MWFs and water-based MWF metrics. Although bladder, rectal, and laryngeal cancers and malignant melanoma have been associated with straight MWF exposure and pancreatic cancer with synthetic MWF in men, there were too few deaths in this female subcohort to examine exposure-response relations for these sites. Results were null for lung and breast cancer. Our findings support an association between colon cancer and straight MWFs, but we found limited evidence of risk for other tumor sites at the lower exposure levels experienced by the female autoworkers.