Aquatic risk assessment of 2-sulfonato fatty acid methyl ester sodium salt (MES).

The aquatic risk of 2-sulfonato fatty acid methyl ester sodium salt (MES) used in household detergents was assessed. The environmental exposure assessment expressed as predicted environmental concentration (PEC) was determined on the basis of monitoring results from the seven sites of four rivers in the urban area in Tokyo and Osaka. The 95 percentile as well as geometric mean of the MES concentration was found to exhibit a good correlation with the geometric mean of the Biochemical Oxygen Demand (BOD; the latter's regression was greater than 0.99). The predicted no effect concentration (PNEC) for the aquatic environment was estimated by performing chronic assays of algae and daphnia. The risk characterization ratio (RCR: PEC/PNEC) was less than 1. Therefore, it is concluded that MES will not adversely affect the aquatic environment in Japan.