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Environmental Risks and Toxicity of Fipronil and Imidacloprid Used in Pets Ectoparasiticides
by
, , , , , , , , and
Lucia De Marchi
1,*
,
Matteo Oliva
2,
Maria Nobile
3,*,
Mario Carere
4,
Luca Maria Chiesa
3,
Donatella Degl’Innocenti
5,
Ines Lacchetti
4,
Laura Mancini
4,
Valentina Meucci
1
,
Carlo Pretti
1,2,
Marzia Vasarri
5
,
Roberto Edoardo Villa
3 and
Luigi Intorre
1 1
Veterinary Teaching Hospital, Department of Veterinary Sciences, University of Pisa, 56124 Pisa, Italy
2
Consortium for the Interuniversity Center of Marine Biology and Applied Ecology “G. Bacci”, 57127 Livorno, Italy
3
Department of Veterinary Medicine and Animal Science, University of Milan, 26900 Lodi, Italy
4
Department of Environment and Health, Italian National Institute of Health, 00161 Roma, Italy
5
Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
*
Authors to whom correspondence should be addressed.
Animals 2025, 15(11), 1533; https://doi.org/10.3390/ani15111533
Submission received: 2 April 2025
/
Revised: 12 May 2025
/
Accepted: 21 May 2025
/
Published: 23 May 2025
(This article belongs to the Special Issue Bivalves as Bioindicators of Environmental Pollution in Aquatic Ecosystems)
Simple Summary
Fipronil (FIP) and imidacloprid (IMID) are common pet treatments for parasites, but their environmental impact is often overlooked. This study monitored their presence in wastewater from an animal shelter in Italy and assessed their effects on marine species and human cells. The findings revealed that FIP and IMID persist in water and can harm aquatic organisms, including copepods and mussels, while also causing toxic effects on human skin cells. These results suggest a need for stricter regulations and further research to understand the long-term environmental and health risks of these chemicals.
Abstract
Fipronil (FIP) and imidacloprid (IMID) are two of the most commonly used ectoparasiticides to control parasites in pets. Compared with those of farm animals, their environmental risks have generally been considered low because of their limited use; however, the growing pet population and evolving treatment practices make this assumption challenging. To assess these risks, water samples were collected at an animal shelter in Italy to monitor the abundance of ectoparasiticides in aquatic environments. Additionally, laboratory-based ecotoxicological assays were carried out on a range of marine non-target species across different trophic levels (algae, copepods, and mussels). In vitro toxicity tests on human epithelial cell cultures were also implemented to examine potential cytotoxic effects at the levels of human exposure detectable in a domestic setting after pet treatment. Wastewater samples from the shelter contained 0.18 µg L−1 of IMID, 0.50 µg L−1 of FIP, and 0.20 µg L−1 of FIP-sulfone, with these concentrations remaining stable for 60 days. Chronic exposure to FIP and IMID at 30.0 µg L−1 impaired the mobility of the copepods. The EC10 and EC20 values were determined to be 1.7 (0.06–6.59) µg L−1 and 2.8 (0.436–8.51) µg L−1 for FIP and 2.6 (0.80–6.33) µg L−1 and 7.6 (3.12–15.8) µg L−1 for IMID, respectively. FIP and IMID exposure led to lipid peroxidation in the digestive glands and gills of mussels, whereas only IMID exposure increased acetylcholinesterase activity in the digestive glands at concentrations between 0.5 and 5.0 µg L−1. Additionally, both fipronil and imidacloprid triggered the production of reactive oxygen species and lipid peroxidation and decreased the viability of human keratinocyte cells in a concentration-dependent manner. These findings highlight the persistence and potential risks of FIP and IMID, stressing the need for stricter regulations and further research on chronic environmental exposure to safeguard ecosystems and public health.
