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Derivation of algal acute to chronic ratios for use in chemical toxicity extrapolations
Citation:
Brill, J., S. Belanger, M. Barron, A. Beasley, K. Connors, M. Embry, AND G. Carr. Derivation of algal acute to chronic ratios for use in chemical toxicity extrapolations. CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 263:9, (2021). https://doi.org/10.1016/j.chemosphere.2020.127804
Impact/Purpose:
The purpose of this manuscript is to communicate the results of a scientific investigation of the relationship between acute and chronic toxicity of chemicals to algal species, known as acute to chronic ratios or ACRs. Algae are important because they are globally accepted in hazard assessment of chemicals as a sensitive taxa and representative surrogate for aquatic plants. The impact of the research is that determining ACRs for algae is vital to the assessment of hazards of chemicals to aquatic plants. Algal toxicity studies are required by regulatory agencies for a variety of purposes including classification and labeling and chemical risk assessment, and algae are frequently the most sensitive taxonomic group tested. ACRs have been challenging to derive for algal species because of the complexities of the underlying experimental data including: a lack of universally agreed upon algal inhibition endpoints; evolution of experimental designs over time and by different standardization authorities; and differing statistical approaches (e.g., regression versus hypothesis-based effect concentrations). Experimental data for developing globally accepted algal ACRs have been limited because of data availability, and in most regulatory frameworks an ACR of 10 is used regardless of species, chemical type or mode of action. Quantitatively and comprehensively deriving and reporting ACRs for algae will positively impact public safety by allowing the assessment of a broader range of chemicals for an important component of aquatic ecosystems: aquatic plants.
Description:
Algal toxicity studies are required by regulatory agencies for a variety of purposes including classification and labeling and environmental risk assessment of chemicals. Algae are also frequently the most sensitive taxonomic group tested. Acute to chronic ratios (ACRs) have been challenging to derive for algal species because of the complexities of the underlying experimental data including: a lack of universally agreed upon algal inhibition endpoints; evolution of experimental designs over time and by different standardization authorities; and differing statistical approaches (e.g., regression versus hypothesis-based effect concentrations). Experimental data for developing globally accepted algal ACRs have been limited because of data availability, and in most regulatory frameworks an ACR of 10 is used regardless of species, chemical type or mode of action. Acute and chronic toxicity (inhibition) data on 17 algal species and 442 chemicals were compiled from the EnviroTox database https://envirotoxdatabase.org/) and a proprietary database of algal toxicity records. Information was probed for growth rate, yield, and final cell density endpoints focusing primarily on studies of 72 and 96 h duration. Comparisons of acute and chronic data based on either single (e.g., growth rate) and multiple (e.g., growth rate, final cell density) endpoints were used to assess acute and chronic relationships. Linear regressions of various model permutations were used to compute ACRs for multiple combinations of taxa, chemicals, and endpoints, and showed that ACRs for algae were consistently around 4 (ranging from 2.43 to 5.62). An ACR of 4 for algal toxicity is proposed as an alternative to a default value of 10, and recommendations for consideration and additional research and development are provided.
URLs/Downloads:
DOI: Derivation of algal acute to chronic ratios for use in chemical toxicity extrapolations