Predicting Earthworm Toxicity in Untested Soils with Toxicokinetic Modelling: Concept and Validation.

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Soil Science

Background:

• Earthworm toxicity tests typically use artificial soils with limited organic matter.
• Soil organic matter and pH significantly affect chemical bioavailability and toxicity.
• Predicting earthworm toxicity in diverse natural soils remains a challenge.

Purpose of the Study:

• To develop a novel approach for predicting chemical effect concentrations in untested soils.
• To improve the environmental realism of earthworm risk assessments.
• To address bias in current risk assessment protocols.

Main Methods:

• Utilized a toxicokinetic model incorporating earthworm species properties, chemical properties (topological polar surface area), and soil characteristics (organic matter, pH).
• Combined results from standard toxicity tests with an empirical model for chemical uptake.
• Validated the predictive model against an independent dataset of 145 effect concentrations.

Main Results:

• The model accurately predicted toxic effect concentrations (EC50 and LC50) for 90% of cases within a factor of 3 of observed values.
• Demonstrated that the new approach removes bias caused by differences between standardized and agricultural soils.
• Showcased potential application using fungicide examples for enhanced environmental risk assessment.

Conclusions:

• The developed model offers a more accurate and environmentally relevant method for earthworm risk assessment.
• This approach can significantly enhance the reliability of chemical safety evaluations in diverse soil environments.
• Application of this model is crucial for refining European risk assessment practices and ensuring ecological safety.