Determination of chlorate and chlorite and mutagenicity of seafood treated with aqueous chlorine dioxide

The use of chlorine dioxide (ClO2) as a potential substitute for aqueous chlorine to improve the quality of seafood products has not been approved by regulatory agencies due to health concerns related to the production of chlorite (ClO2-) and chlorate (ClO3-) as well as possible mutagenic/carcinogenic reaction products. Cubes of Atlantic salmon (Salmo salar) and red grouper (Epinephelus morio) were treated with 20 or 200 ppm aqueous chlorine or ClO2 solutions for 5 min, and extracts of the treated fish cubes and test solutions were checked for mutagenicity using the Ames Salmonella/microsome assay. No mutagenic activity was detected in the treated fish samples or test solutions with ClO2. Only the sample treated with 200 ppm chlorine showed weak mutagenic activity toward S. typhimurium TA 100. No chlorite residue was detected in sea scallops, mahi-mahi, or shrimp treated with ClO2 at 3.9-34.9 ppm. However, low levels of chlorate residues were detected in some of the treated samples. in most cases, the increase in chlorate in treated seafood was time- and dose-related.