Risk assessment for metalworking fluids and cancer outcomes

Background Metalworking fluids (MWF) are complex mixtures with dermal and inhalation exposure. Published reports reveal excess cancer risk. Methods Using published findings exposure response was derived for each attributable cancer site. Aggregate excess lifetime risk was estimated by applying a lifetable calculation. Results Cancer sites contributing the most attributable cases were larynx, esophagus, brain, female breast, and uterine cervix. With constant workplace MWF exposure of 0.1 mg/m3 over a 45 years working life, the risk of attributable cancer was 3.7% or, excluding the less certain female cancers, 3.1%. Conclusion Substantial cancer risks occurred at 0.1 mg/m3 MWF, one fourth of the current NIOSH recommended exposure limit for MWF total particulate. Because ingredients in current MWF remain from earlier formulations, it is likely that some MWF carcinogenicity persists today. Although important changes have occurred, newer agents are being continually introduced with little or no knowledge of chronic health risks.