Assessing the Risks to Bats from Plant Protection Products: A Review of the Recent European Food Safety Authority Statement Regarding Toxicity and Exposure Routes

Temperature-dependent in vitro hepatocytotoxicity of insecticides in bats

Heterothermic insectivorous bats are supposed to experience differential adverse effects of insecticidal pollutants depending on their seasonal and/or daily variation of metabolic and detoxification rates. Here, we investigated effects of imidacloprid, cypermethrin and fipronil on Nyctalus noctula bat-derived hepatocytes through cytotoxicity, cell inhibition and death at different concentrations (0.01, 0.1, 1, 10, 100, 1000 μg/ml), exposure times (10, 24, 48 hrs), incubation temperatures simulating hibernation (8 °C), daily torpor (20 °C), normothermy (37 °C) and active flight (40 °C), and cytochrome P450 addition. Toxic effects were significantly influenced by temperature (p < 0.05), with strong cytotoxicity after 10 hour exposure to fipronil or cypermethrin at 37 and 40 °C, cell replication inhibition (all insecticides at 8 °C) and cellular stimulation, with slight culture proliferation after 48 hours (all insecticides at 40 °C). Replacing protected chiropterans with cell cultures is a way to assess and extrapolate risks of insecticides for bats.

Toxicological effects assessment for wildlife in the 21st century: Review of current methods and recommendations for a path forward

Model species (e.g., granivorous gamebirds, waterfowl, passerines, domesticated rodents) have been used for decades in guideline laboratory tests to generate survival, growth, and reproductive data for prospective ecological risk assessments (ERAs) for birds and mammals, while officially adopted risk assessment schemes for amphibians and reptiles do not exist. There are recognized shortcomings of current in vivo methods as well as uncertainty around the extent to which species with different life histories (e.g., terrestrial amphibians, reptiles, bats) than these commonly used models are protected by existing ERA frameworks. Approaches other than validating additional animal models for testing are being developed, but the incorporation of such new approach methodologies (NAMs) into risk assessment frameworks will require robust validations against in vivo responses. This takes time, and the ability to extrapolate findings from nonanimal studies to organism- and population-level effects in terrestrial wildlife remains weak. Failure to adequately anticipate and predict hazards could have economic and potentially even legal consequences for regulators and product registrants. In order to be able to use fewer animals or replace them altogether in the long term, vertebrate use and whole organism data will be needed to provide data for NAM validation in the short term. Therefore, it is worth investing resources for potential updates to existing standard test guidelines used in the laboratory as well as addressing the need for clear guidance on the conduct of field studies. Herein, we review the potential for improving standard in vivo test methods and for advancing the use of field studies in wildlife risk assessment, as these tools will be needed in the foreseeable future. Integr Environ Assess Manag 2024;20:699-724. © 2023 His Majesty the King in Right of Canada and The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Reproduced with the permission of the Minister of Environment and Climate Change Canada. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

One Health challenges for pig reproduction

The current state of the world challenges pig reproduction as an important part of One Health, which involves interrelationships between animal, human and environmental health. The One Health concept underlines a comparative aspect in reproductive physiology and disease occurrence, bridging knowledge from one species to another. Seasonal changes in the environment affect pig reproduction and climate change may further strengthen those effects. Endocrine-disrupting chemicals (EDCs), and specifically phthalates and heavy metals, interfere with endocrine function, and thereby sexual behavior, fertilization capacity and steroidogenesis. Reproductive infections and extended semen storage are important indications for antimicrobial use. Innovative solutions are needed to explore alternatives to antimicrobials. Efforts to ensure reproductive efficiency have prolonged farrowing as litter size has doubled over the past three decades, compromising immune transfer and welfare. Physiological, metabolic and programming related events around parturition are key areas for future One Health research in pig reproduction. In conclusion, climate change challenges reproductive management and breeding. More resilient pigs that can tolerate harsh environment but maintain high reproductive performance are needed. EDCs continue to grow as an environmental challenge for reproductive management and alternatives to antibiotics will be required.

Predicted Dermal and Dietary Exposure of Bats to Pesticides

Wild birds and mammals that feed in agricultural habitats are potentially exposed to pesticides through various routes. The European Food Safety Authority (EFSA) recently published a statement which concluded that the current EFSA risk assessment scheme for birds and mammals does not adequately cover bats (Chiroptera). In the present study, we take a more detailed look at the EFSA statement and assumptions made regarding direct (dermal) and indirect (dietary) exposure of bats to pesticides in terms of their realism and the potential implications for risk assessment outcomes. Regarding dietary exposure, errors in the residue per unit dose (RUD) values for flying insects (bat food), proposed in the EFSA bat statement, were identified and corrected. Lower RUD values based on a much broader data base are proposed. Using these more realistic RUD values, together with current assumptions regarding toxicity and exposure, the acute and long-term risk to bats appears to be within the range of those calculated for birds and ground-dwelling mammals under the current risk assessment scheme. Depending on the assumptions made, some uncertainties may remain and should be investigated further. According to the EFSA bat statement, dermal exposure of bats is the most significant route of exposure, resulting in the highest predicted daily doses. We demonstrated that the dermal exposure models in the EFSA bat statement predict much higher residues for bats than those measured for other flying organisms that have larger surface area to volume ratios, and thus would be expected to have the reverse relationship. We also illustrated that the amounts of spray liquid required to achieve the predicted dermal exposures of bats are implausibly high, with bats carrying an amount of spray liquid that exceeds their body weight many fold. It is recommended that a bat risk assessment framework should be based on realistic, sound science, allowing resources to be focused on those scenarios that are not already covered by the existing bird and mammal framework. Therefore, a quantitative risk assessment scheme should not be implemented until the many scientific uncertainties within the EFSA bat statement are addressed. Environ Toxicol Chem 2022;41:2595-2602. © 2022 Cambridge Environmental Assessments. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.