"Population-level Ecological Risk Assessment on Alcohol Ethoxylate Surfactant Mixtures"

LIN Bin-Le, Meng Yaobin, Satoko Matuura, Akihiro Tokai

National Institute of Advanced Industrial Science and Technology

 SETAC North America 27th Annual Meeting (Montreal, Canada 2006/11/8)

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Abstract

Alcohol ethoxylates (AE), a class of nonionic surfactants consisted of mixtures of varying degrees of alkyl carbons with ethylene oxide (homologues), continues to be one of the top ten chemicals released to Japanese environment based on the reported data of PRTR law (specified homologues of 12-15 alkyl carbons, C12-15) these years. No existing risk assessment in Japan has revealed the real risk of AE due to the lack of methods and information on its characteristic as mixtures of homologues with different environmental fate and eco-toxicity. 
The environmental fate and effects of AE are linked to the profile (environmental fingerprint) of the AE homologue distribution in a mixture. We employed the newest analytical method to acquire the information for its homologues profile in environment including their fate and concentration. A neural network system for prediction of eco-toxicity data for each homologue on typical aquatic organism was established. Based on the available eco-toxicity data of each homologue from neural network system, we proposed an extrapolation approach for deriving the threshold concentration for population-level ecological risk assessment (Clambda=1). Deriving HC5 for each homologue was also performed through analysis of species sensitivity distributions. 
Using the available information on Japanese environmental exposure (monitoring homologues concentration) and derived values of Clambda=1 and HC5 for each homologue, a toxic unit fraction for describing the potential risk of each homologue was calculated, respectively. These results implicate that the specified range homologues of PRTR law only represents a part of risk of AE, and the current risk of AE is not at alert level in most of the Japanese aquatic environment. 

Keywords

Alcohol ethoxylates (AE), population-level ecological risk assessment (PLERA), mixtures