Comparisons of PNEC derivation logic flows under example regulatory schemes and implications for ecoTTC

• Published in: Regulatory toxicology and pharmacology Vol. 123; p. 104933
• Main Authors: Belanger, S.E., Beasley, A., Brill, J.L., Krailler, J., Connors, K.A., Carr, G.J., Embry, M., Barron, M.G., Otter, R., Kienzler, A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.07.2021
• Subjects: Animals; Aquatic; Databases, Factual; Hazard; Hazardous Substances - toxicity; Logic; No-Observed-Adverse-Effect Level; Predicted No Effect concentration; Probability; Risk Assessment; Statistic; Threshold of toxicologic concern; Toxicity Tests, Chronic - methods; Water Pollutants, Chemical; Threshold of toxicologic concern; Statistic; Aquatic; Predicted No Effect concentration; Hazard
• ISSN: 0273-2300; 1096-0295; 1096-0295
• DOI: 10.1016/j.yrtph.2021.104933

Derivation of Predicted No Effect Concentrations (PNECs) for aquatic systems is the primary deterministic form of hazard extrapolation used in environmental risk assessment. Depending on the data availability, different regulatory jurisdictions apply application factors (AFs) to the most sensitive measured endpoint to derive the PNEC for a chemical. To assess differences in estimated PNEC values, two PNEC determination methodologies were applied to a curated public database using the EnviroTox Platform (www.EnviroToxdatabase.org). PNECs were derived for 3647 compounds using derivation procedures based on example US EPA and a modified European Union chemical registration procedure to allow for comparisons. Ranked probability distributions of PNEC values were developed and 5th percentile values were calculated for the entire dataset and scenarios where full acute or full chronic data sets were available. The lowest PNEC values indicated categorization based on chemical attributes and modes of action would lead to improved extrapolations. Full acute or chronic datasets gave measurably higher 5th percentile PNEC values. Algae were under-represented in available ecotoxicity data but drove PNECs disproportionately. Including algal inhibition studies will be important in understanding chemical hazards. The PNEC derivation logic flows are embedded in the EnviroTox Platform providing transparent and consistent PNEC derivations and PNEC distribution calculations. [Display omitted] •Transparent logic for PNEC derivation would improve environmental risk assessment.•EnviroTox (www.EnviroToxdatabase.org) was used to develop PNECs for two example assessment systems and ~3500 compounds.•PNECs are driven disproportionately by algal and invertebrate toxicity.•Ecological thresholds of toxicologic concern can be developed on a regional basis using explicit PNEC logics.