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Teratogenesis, toxicity, and bioconcentration in frogs exposed to dieldrin
G S Schuytema1, A V Nebeker, W L Griffis
1U.S. Environmental Protection Agency, Corvallis Environmental Research Laboratory, Oregon 97333.
Archives of Environmental Contamination and Toxicology
|September 1, 1991
Summary
This study investigated dieldrin toxicity in three frog species, finding Xenopus laevis most sensitive to chronic exposure and Rana catesbeiana to acute tadpole tests. Results inform wildlife-based water quality criteria.
Area of Science:
- Environmental toxicology
- Amphibian ecotoxicology
- Wildlife toxicology
Background:
- Development of wildlife-based water quality criteria requires understanding contaminant impacts on diverse species.
- Dieldrin is a persistent organic pollutant with known toxicity, necessitating evaluation across different life stages.
Purpose of the Study:
- To assess teratogenesis, acute and chronic toxicity, growth, and bioconcentration of dieldrin in Xenopus laevis, Rana catesbeiana, and Rana pipiens.
- To determine species-specific sensitivities and identify critical endpoints for risk assessment.
Main Methods:
- Exposure of frog embryos, tadpoles, juveniles, and adults to aqueous dieldrin in static-renewal and flow-through systems.
- Acute (96-h LC50) and chronic (24- or 28-day LC50, LOAEL, NOAEL) toxicity testing.
- Observation of teratogenic effects, specifically spinal deformities.
Main Results:
- Rana catesbeiana showed highest tadpole sensitivity in acute tests; Xenopus laevis was most sensitive in embryo-larval and chronic tadpole tests.
- LC50 values varied significantly, with tadpole 96-h LC50s ranging from 8.7 to 71.3 µg/L.
- Spinal deformities observed in Xenopus laevis at 1.3 µg/L and in Rana catesbeiana at 25.4 µg/L.
Conclusions:
- Xenopus laevis and Rana catesbeiana exhibit distinct sensitivities to dieldrin across different exposure durations and life stages.
- Findings provide crucial data for establishing safe dieldrin concentrations in aquatic environments to protect amphibian populations.