Quantitative risk assessment as the basis for a proposed NIOSH recommended exposure limit for hexavalent chromium compounds.
MacMahon-K; Park-R; Rice-F; Ashley-K
Toxicologist 2013 Mar; 132(1):337-338
To update the National Institute for Occupational Safety and Health (NIOSH) recommendations for protecting workers with occupational exposure to Cr(VI) compounds, all aspects of occupational exposure to and control of hexavalent chromium compounds (Cr(VI); e.g., chromic acid, CAS No. 1333-82-0; sodium dichromate, CAS No. 7789-12-0) were evaluated including epidemiology, toxicology, risk assessment, analytical methods, and industrial hygiene practices. Derivation of a proposed Recommended Exposure Limit (REL) was one component of the updated risk management recommendations. The NIOSH proposed REL was derived based on the results of a quantitative risk assessment (QRA) of lung cancer in chromate production workers. The NIOSH REL was previously based on the quantitative limitation of the 1975 analytical method; at that time NIOSH recommended that occupational carcinogens be controlled to the lowest feasible concentration. Data from a cohort of Baltimore chromate production workers were selected for analysis due to the availability of extensive exposure assessment data, information about smoking histories, strong statistical power, and relative lack of confounding exposures. Excess lifetime risk at the REL of 1 microg Cr(VI)/m3 was estimated as 6 (95% confidence limits=3-12) lung cancer deaths per 1000 workers. Based on these results, NIOSH proposed a REL of 0.2 microg Cr(VI)/m3 8-hour time-weighted average exposure during a 40-hour workweek. The proposed REL has an estimated working lifetime (45 years) excess risk of lung cancer mortality of approximately one in 1000. NIOSH, Occupational Safety and Health Administration, and international consensus standard analytical methods can accurately quantify workplace exposures at the proposed REL. Recommending the control of occupational Cr(VI) exposures to below the proposed REL is intended to reduce the incidence of work-related lung cancer.
Toxicology; Exposure-assessment; Risk-analysis; Exposure-levels; Exposure-limits; Permissible-concentration-limits; Hexavalent-chromium-compounds; Chromium-compounds; Acids; Epidemiology; Analytical-methods; Industrial-hygiene; Chromates; Lung-cancer; Cancer; Carcinogens; Quantitative-analysis; Lifespan; Mortality-data
18540-29-9; 1333-82-0; 7789-12-0
The Toxicologist. Society of Toxicology 52nd Annual Meeting and ToxExpo, March 10-14, 2013, San Antonio, Texas