Dermal exposure represents a major pathway of chlorpyrifos uptake in insectivorous bats: Insights from a toxicokinetic model.

Bats help to control populations of agricultural pests by eating large amounts of insects; however, foraging in croplands can present a threat to bats through exposure to pesticides via contaminated prey or through their skin and lungs. Although exposure to pesticides is known to occur in bats, it is unclear which routes predominate, and how toxic compounds are distributed among different tissues after being taken up from the environment. A non-invasive approach to evaluating the risk of exposure is the use of toxicokinetic modeling. Here, we developed a physiologically-based toxicokinetic model to evaluate how Chlorpyrifos, a widely used insecticide, is taken up, metabolized, distributed, and excreted in the insectivorous bat Eptesicus fuscus, as a model species, under multiple exposure scenarios. Simulations showed that dermal exposure can be a major route of pesticide uptake, especially when bats forage in soybean and corn fields, with dermal uptake predicted to be approximately 600-fold greater than in rats under comparable exposure assumptions. Dermal exposure appears to be a uniquely important route of pesticide uptake in bats and should therefore be explicitly considered in future pesticide risk assessments. This information is key to understanding the significance of toxicant exposure as a threat to bat conservation.