PARENT SESSION

2A - Mixture Toxicity
Hall 6
8:30 AM - 12:30 PM, Monday, 28 April 2003
Chair: Hermens, J.¹, ¹
Co-chair: Toy, R.², Backhaus, T.³, ^{2 3}

(MO6/9) Refined environmental risk assessment of alcohol ethoxylate surfactants.

Marshall, Stuart¹, Boeije, Geert², Cano, Manuel³, Dorn, Phil³, Toy, Robin⁴, Wind, Thorsten⁵, Guembel, Helmut⁶, van Compernolle, Remi³, Belanger, Scott⁷, ¹ Unilever, Bedford, UK² Procter & Gamble, Brussels, Belgium³ Shell, Houston, USA⁴ Shell, London, UK⁵ Henkel, Dusseldorf, Germany⁶ BASF, Ludwigshafen, Germany⁷ Procter & Gamble, Cincinnati, USA

ABSTRACT- Linear-type alcohol ethoxylates, AE, are nonionic surfactants used in a wide range of cleaning products. Commercial AE are complex mixtures of relatively simple and similar structures, varying in the length of alkyl (carbon) chain and number of attached ethylene oxide (EO) units. In the mid-1990′s an aquatic environmental risk assessment of AE in the Netherlands indicated acceptable safety margins. Since then two key developments have enabled the risk assessment to be refined and expanded to include several EU countries. Firstly, a highly sensitive and specific analytical method has been developed so that a wider range of AE components (C_12-18 EO_0-18) can be determined. This method has been used to analyse samples of sewage effluents taken from activated sludge plants in several European countries. The measured C/EO ′environmental fingerprints′ differ from those of commercial AEs particularly in the proportion of un-ethoxylated alcohol (EO=0) compared to ethoxylated components (EO>0). Secondly, mixture toxicity theory and QSARs have been developed to predict the joint toxicity of all components of an AE fingerprint. This refinement enables the toxicity of any environmental fingerprint to be predicted from toxicity data based on commercial products that are mixtures with a different fingerprint. Such an assessment is more robust than an assessment based on average structures. By comparing the distribution of each environmental fingerprint with the appropriate PNEC, the risk quotient for each sampling location can be determined. Preliminary results of the refined assessment confirm the outcome of the earlier Dutch RA.

Key words: environmental monitoring, alcohol ethoxylates, risk assessment