Application of Basin Wide Ecological Models (Bawems) to the Fate of LAS in Tokyo Bay

Abstract

The primary purpose of this study was to simulate the environmental fate of the homologues of linear alkylbenzene sulfonates (LAS). These were selected as representative chemicals with middle-range aquatic toxicity and environmental persistence, which are used in rather large amounts. A secondary purpose was to determine the composition ratio (i.e., the relative percentages of LAS homologues) of LAS products which results in the minimum risk potential in sediments. The following results were obtained from model simulations: 1. By applying basin wide ecological models (BAWEMs) to Tokyo Bay and the surrounding watershed, distribution patterns of LAS homologues in river water, river sediment, seawater, and sea sediment were relatively well simulated. 2. The minimum risk composition ratio of LAS, with the constraint of considering detergent cleaning capacity, is capable of reducing by about 60% the risk potential of the composition ratio of popularly supplied LAS. Reported composition ratios of LAS in existing consumer products are all in the same or rather low risk level categories. It can be concluded that one of the effective strategies of chemical risk management, particularly with reference to alkylbenzene-based synthetic detergents, is alteration of the composition ratio of LAS.