SUBSTANCE PROFILES Strong Inorganic Acid Mists Containing Sulfuric Acid CAS No. 7664-93-9 (Sulfuric Acid)

Strong inorganic acid mists containing sulfuric acid are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans that indicate a causal relationship between exposure to strong inorganic acid mists containing sulfuric acid and human cancer. Occupational exposures to strong inorganic acid mists containing sulfuric acid are specifically associated with laryngeal and lung cancer in humans. Steenland et al. (1988) reported on studies of one U.S. cohort of male workers in pickling operations in the steel industry, which showed excesses of laryngeal cancer (approximately two-fold) after adjusting for smoking and other potential confounding variables. In a ten-year follow-up, Steenland (1997) reported a two-fold laryngeal cancer rate ratio consistent with previous findings from this cohort. In a nested case-control study of workers in a U.S. petrochemical plant, Soskolne et al. (1984) found a dose-response for laryngeal cancer risk among workers exposed to moderate (odds ratio [OR] of 4.6; 95% CI, 0.83 to 25.35) or high levels (OR of 13.4; 95% CI, 2.08 to 85.99) of sulfuric acid. In a Canadian population-based case-control study, after controlling for tobacco and alcohol use and including only the most specific exposure scale, Soskolne et al. (1992) also observed a dose-response for laryngeal cancer risk in workers exposed to sulfuric acid mist. A report of a similar population-based case-control study in Canada by Siemiatycki (1991) also suggested an increase in risk for oat-cell carcinoma of the lung. Steenland and Beaumont (1989), reporting on the same U.S. cohort of male workers in pickling operations described by Steenland et al. (1988), found an excess of lung cancer in these workers after adjusting for smoking and other potential confounding variables. No adequate experimental animal carcinogenicity studies of sulfuric acid or strong inorganic acid mists containing sulfuric acid have been reported in the literature.