Predictive exposure modelling - A case study with a detergent surfactant

Environmental exposure estimations are generally based on a knowledge of ho w and in what quantity a substance enters the environment and how it may su bsequently be distributed and transformed. Once present within the environm ent, biota (including man) may be exposed. This paper outlines the tools co mmonly used to estimate environmental exposure to ingredients from detergen ts and other household products. Such products are typically manufactured i n large quantities, used by many people, and disposed of after household us e into the environment via the sewer. The vast majority of this waste strea m is treated via domestic wastewater treatment plants (WWTPs) as documented in the sewage treatment via reactive 91/275/EEC. WWTPs significantly reduc e the load of chemical substances to the receiving surface waters, and have become an intrinsic part of exposure and risk assessment of household chem icals. WWTP models are generally first-order (e.g. SIMPLETREAT, WWTREAT) or mixed-order (e.g, Monod) kinetics and can exhibit, potentially, very disti nct dependencies on the influent concentration. Thus, the correct represent ation of xenobiotic behaviour in a WWTP and modeling of their fate has a si gnificant impact on exposure assessment. The Environmental Risk Assessment Steering Committee (ERASM) of the Association Internationale de la Savonner ie et la Detergence. et des Produits d'Entretiens (AISE) and the Comite Eur opeen de Agents de Surface et Intermediares Organiques (CESIO) has commissi oned a joint industry Task Force of the Association to develop and apply sp ecific methodology for the environmental monitoring of surfactants, and ver ification of fate models. The monitoring programmes have been designed to ( 1) establish the fate, distribution and concentrations of the major surfact ants used in detergents-linear alkylbenzene sulfonate (LAS), alcohol ethoxy lates (AE), alcohol ethoxylaled sulfates (AES) and soap in relevant environ mental compartments and (2) to provide the necessary data for checking the applicability of mathematical models to predict their fate and concentratio ns in these environmental compartments. The case study detailed here, speci fically focuses on the refinement of the LAS exposure assessment for surfac e waters in The Netherlands. (C) 2000 Published by Elsevier Science Ltd. Al l rights reserved.