Systematic review and quantification of respiratory cancer risk for occupational exposure to hexavalent chromium
Aim To investigate the exposure-risk relationship for occupational chromium (VI) exposure and lung cancer in order to establish exposure limits.
Methods We systematically searched for studies reporting on occupational Cr(VI) exposure and cancers of the respiratory tract. To be included, studies needed to provide data for more than one level of occupational Cr(VI) exposure, adequately consider the confounder smoking and be of adequate methodological quality. Because direct genotoxicity was considered the predominant mechanism of carcinogenesis of Cr(VI), linear models were applied in order to fit risk data. Relative risks were calculated based on these linear regression models and then used to estimate excess absolute risks.
Results Five studies of two cohorts of chromium production workers in Baltimore, Maryland, and Painesville, Ohio, were included. Based on different estimates for the exposure effect, the absolute excess risk was found to be “acceptable” (less than 4 per 10,000 according to the German Committee on Hazardous Substances, “AGS”) at a Cr(VI) concentration of 0.1 μg/m3, and became “intolerable” (more than 4 per 1,000) beyond a Cr(VI) concentration of 1 μg/m3.
Conclusion Occupational exposure limits for Cr(VI) based on excess absolute risks can be derived from published data identified by a systematic literature review.