Bromate reduction in simulated gastric juice

Bromate decomposition kinetics with simulated stomach/gastric juice was studied to contibute to more accurate determination of the risk of environmentally relevant exposures to bromate. Any presystemic reduction in the stomach would yield lower risks. Bromate is rapidly reduced by hydrogen sulfide (H2S); half‐lives were 153 min at zero H2S and 2, 24, and 32 min at 10−4, 10−5, and 10−6 M H2S, respectively. Half‐lives at 10−4 and 10−5 M are biologically relevant for the retention time for water in an empty stomach. Common dietary inorganic reducing agents (ferrous, iodide, and nitrite) generally enhanced bromate reduction with H2S. Oxidizing agents (hypochlorous acid/chlorine, chloramine, and ferric ion) usually modestly reduced decomposition rates with H2S. Consumption of chlorinated or chloraminated drinking water containing bromate would not materially affect the extent of presystemic bromate reduction. Current studies by the authors are quantifying bromate reduction from the greater systemic liver and blood metabolism, where rapid reactions with glutathione and other reducing agents occur.