Derivation of avian dermal LD50 values for dermal exposure models using in vitro percutaneous absorption of [14 C]-atrazine through rat, mallard, and northern bobwhite full thickness skin

The Science of the Total Environment
Jonathan D MaulRichard A Brain

Abstract

Understanding dermal exposure is important for higher-tier avian ecological risk assessments. However, dermal exposure and toxicity are often unknown for avifauna. The US EPA's Terrestrial Investigation Model (TIM) uses a method to estimate avian dermal LD50 values (and ultimately dermal exposure) that frequently results in unusually high dermal exposure and low dermal LD50 estimates. This is primarily a result of using organophosphate and carbamate toxicity data to develop the oral-dermal relationship. An estimated dermal LD50 is necessary to generate a dermal route equivalency factor that normalizes potency relative to oral toxicity within the dermal pathway dose equation. In this study, atrazine dermal absorption experiments were conducted with mallard, northern bobwhite, and rat skin. These data were used to derive an avian-mammal dermal route equivalency factor for atrazine and introduce a new approach for estimating dermal LD50 values and ultimately predicting exposure via the TIM dermal pathway. Compared to the default TIM method, this new approach yielded TIM output with lower mean total dose, lower dermal fraction of total dose, greater oral fraction of total dose, and reduced model predicted mortality for atrazine. In...Continue Reading

Citations

Mar 10, 2019·Annals of Work Exposures and Health·Henk A GoedeJody Schinkel
Jul 6, 2021·Journal of Toxicology and Environmental Health. Part B, Critical Reviews·Philip N SmithKeith R Solomon

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