Predicting fish acute toxicity using a fish gill cell line-based toxicity assay.

Area of Science:

• Environmental Toxicology
• In Vitro Toxicology
• Chemical Safety Assessment

Background:

• OECD Test Guideline 203 for fish acute toxicity relies on high animal numbers and lethality endpoints.
• Existing fish cell line assays often lack the sensitivity of whole-animal tests.

Purpose of the Study:

• To develop and validate a sensitive fish gill cell line-based assay (RTgill-W1) as an alternative to traditional fish acute toxicity testing.
• To assess the accuracy of the RTgill-W1 assay across a diverse range of organic chemicals.

Main Methods:

• Development of an optimized fish gill cell line (RTgill-W1) assay to enhance sensitivity.
• Application of the assay to determine the toxicity of 35 diverse organic chemicals.
• Comparison of in vitro effective concentrations with in vivo data from OECD Test Guideline 203.

Main Results:

• The RTgill-W1 assay demonstrated good agreement with in vivo toxicity for 73% of tested compounds (within 5-fold difference).
• The assay successfully predicted toxicity for baseline toxicants and compounds with specific modes of action.
• Accounting for measured concentrations resolved outliers, though some (e.g., allyl alcohol, permethrin) remained significant.

Conclusions:

• The RTgill-W1 assay is a viable alternative for predicting fish acute toxicity, reducing reliance on animal testing.
• Further assay development could expand its utility within adverse outcome pathways for chronic toxicity assessments.
• This in vitro method supports the replacement, reduction, and refinement of animal testing in chemical risk assessment.