Linear alkylbenzene sulfonate (LAS) is an anionic surfactant widely used in laundry detergents. The environmental safety of LAS has been extensively reviewed in various chemical safety assessment programs worldwide. In this paper, we report an LAS aquatic environmental risk assessment of Japanese rivers using a high-tier assessment approach. For the exposure assessment, river water monitoring data of more than 400 samples were used to determine predicted environmental concentrations (PECs) which were then verified with the AIST-SHANEL exposure model. For the effect assessment, a statistical extrapolation approach using chronic ecotoxicity data was used. Toxicity data were normalized to the average alkyl chains found in the environment (C11.3) and to that of commercial LAS average alkyl chains in Japan (C11.8). Mesocosm data were also normalized to determine the predicted no-effect concentration (PNEC) in the environment. The 95th percentile PECs for detected concentrations in Japanese rivers were 32 to 45 μg/L, and the PNECs were 270 (C12) to 530 (C11.3) μg/L based on mesocosm data with an assessment factor of 1 and supported by data from the statistical extrapolation approach. The PEC was about 10 times lower than the PNEC. From the result of the risk characterization, it was concluded that the aquatic environmental risk posed by LAS in Japan is low.
