Development of species sensitivity distributions for wildlife using interspecies toxicity correlation models

Species sensitivity distributions (SSD) are probability distributions of chemical toxicity of multiple species and have had limited application in wildlife risk assessment because of relatively small data sets of wildlife toxicity values. Interspecies correlation estimation (ICE) models predict the acute toxicity to untested taxa from known toxicity of a single surrogate species. ICE models were used to predict toxicity values to wildlife species and generate SSDs for 23 chemicals using four avian surrogates. The hazard levels associated with the fifth percentile of the distribution (HD5) were compared for ICE SSDs and independent SSDs created with measured data. SSDs were composed of either avian only or avian and mammalian taxa. ICE HD5s were within 5-fold of 90% of measured HD5s and were generally higher than measured HD5s. The first percentile of the distribution (HD1) and the fifth percentile of the lower confidence limit (HDL) of ICE SSDs produced values that were not significantly different from measured HD5s. Using a bird surrogate to predicttoxicity to birds and the Norway rat to predict toxicity to mammals improved some estimates of ICE HD5s compared with those generated using only bird surrogates. These results indicate that ICE models can be used to generate SSDs comparable to those derived from measured wildlife toxicity data and provide robust estimates of the HD5.