John Wiley & Sons, Ltd.

Augmenting aquatic species sensitivity distributions with interspecies toxicity estimation models

Species sensitivity distributions (SSD) are cumulative distribution functions of species toxicity values. The SSD approach is increasingly being used in ecological risk assessment, but is often limited by available toxicity data necessary for diverse species representation. In this study we evaluate augmenting aquatic species databases limited to standard test species with toxicity values extrapolated from interspecies correlation estimation (ICE) models for SSD development. We compared hazard concentration at the 5th centile (HC5) of SSDs developed using limited measured data augmented with ICE toxicity values (augmented SSDs) with those estimated using larger measured toxicity datasets of diverse species (reference SSDs). When SSDs had similar species composition to reference SSDs, 0.76 of the HC5 estimates were closer to reference HC5; however, the proportion of augmented HC5s that were within 5‐fold of the reference HC5s was 0.94, compared to 0.96 when predicted SSDs had random species assemblages. Range of toxicity values among represented species in all SSDs was also dependent on the mode of action of a chemical. Predicted HC5 estimations for acetylcholinesterase inhibitors showed the greatest discrepancies from reference HC5 when SSDs were limited to only commonly tested species. The results of this study indicate that ICE models used to augment datasets for SSDs do not greatly affect HC5 uncertainty. Uncertainty analysis of risk assessments using SSD hazard concentrations should address the species composition especially for chemicals with known taxa‐specific differences in toxicological effects. Environ Toxicol Chem © 2013 SETAC

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