Reproductive risk of Neonicotinoids: A review of male rodent studies.

Background: Neonicotinoid pesticides (neonics) are the most widely used insecticides in the world. Numerous studies have identified detectable levels of neonics in soil and water, and population-based biomonitoring studies have documented human exposure. Neonics are designed to target the insect nervous system; however, their mechanisms of action have been shown to affect the mammalian nervous system. The impacts on human reproductive systems remain largely unknown.

Methods: A review of experimental studies examining reproductive toxicity of neonics in male rodents was conducted. Studies published in English between 2005 and 2025 were identified using the PubMed, and Web of Science databases. Study outcomes were restricted to endocrine and/or reproductive endpoints in male rats and mice. Studies were evaluated for bias using Office of Health Assessment and Translation criteria.

Results: Twenty-one studies were identified that varied widely by neonic, administered dosage, and the reproductive health outcomes investigated. All studies demonstrated negative impacts on male reproductive endpoints in association with neonic exposure, including reduced sperm count, reduced sperm motility, and altered sperm morphology.

Conclusions: This narrative review employed a systematic approach and determined that neonics exhibit reproductive toxicity in male rats and mice, particularly impairing testicular function and sperm quality at high exposure levels. Despite species-specific differences, the conserved nature of reproductive processes across mammals supports the relevance of these findings to human health. The convergence of animal data, and the lack of human epidemiological studies to date, show a critical need to investigate potential reproductive health risks of neonic exposure in humans.