An international collaborative study critically reviewed the derivation methods for ecological screening values (ESVs) protective of aquatic and terrestrial ecology that are currently endorsed and adopted in Australia, Belgium, Canada, the Netherlands and the United States of America. The study identified that each country adopted different ESV derivation methods, accounted for bioaccumulation differently, and incorporated background concentrations and toxicity modifying factors (e.g. temperature, salinity and pH) in different ways. These results highlighted the importance of understanding the sources of data and the science used to underpin the ESV rather than blindly applying values during Tier 1 chemical screening for the protection of ecology.
To inform the appropriate selection of ESVs, we have developed a methodology to rank and score multiple ESVs based on key or desirable derivation attributes such that scientifically robust and environmentally relevant ESVs are identified. The scoring system considers the ESV derivation methodology (e.g., species sensitivity distributions, assessment factors, or other extrapolations), the underlying database (e.g., species/taxa represented, acute vs. chronic data, biological endpoint) and the level of species protection afforded to the ESV. Ultimately, we have developed a transparent and informed approach to the selection and adoption of ESVs based on country or site-specific needs and relevance.
We will present the key aspects of our critical review of the existing ESVs, the methodology to rank and score multiple ESVs for each chemical, and further country-specific considerations we identified for their selection and adoption. Our study and findings will provide a technical framework to ensure the selection of existing ESVs are technically robust and environmentally relevant particularly for jurisdictions without nationally endorsed/derived ESVs.