Species sensitivity distributions (SSDs) are logistic cumulative probability
distributions of toxicity values for multiple species. For environmental risk assessment,
the chemical concentration that is protective of most species (95%) is extrapolated from
an SSD as the corresponding 5th percentile (HC5) of the distribution (Dyer et al. 2006).
This SSD module generates an SSD for a chemical from Web-ICE
estimated toxicity values when only the toxicity of one surrogate species is known.
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