From Environmental Fate to Ecological Risk: A Review of Nitenpyram's Behavior, Degradation Pathways, and Ecotoxicity Impacts

Nitenpyram (NIT), a widely used neonicotinoid insecticide, has gained attention due to its extensive use in agriculture and veterinary medicine and frequent detection in aquatic and terrestrial environments. Although considered relatively short-lived, evidence suggests NIT exhibits complex environmental behavior and notable ecological risks under realistic exposure. This review provides a comprehensive integration of current knowledge on the physicochemical properties, environmental fate, degradation pathways, and ecotoxicological impacts of NIT. We summarize NIT’s sources and distribution in surface waters, sediments, soils, and biota, emphasizing its high water solubility, mobility, and continuous input via agricultural runoff and wastewater. Key abiotic and biotic degradation processes—including photolysis, hydrolysis, and microbial transformation—are evaluated, with focus on the formation and ecological relevance of transformation products. Toxicological evidence shows that NIT induces acute and chronic effects in aquatic invertebrates, fish, and non-target organisms through neurotoxicity, oxidative stress, endocrine disruption, and behavioral changes, often at environmentally relevant concentrations. Major limitations in current risk assessments include overreliance on short-term endpoints, limited consideration of mixture effect, and neglect of transformation products and food web–mediated exposure. Future research should prioritize mechanism-informed toxicity assessment, realistic exposure scenarios, and integrated fate–effect modeling. Overall, NIT’s environmental risks are likely underestimated, highlighting the need for a holistic, ecosystem-relevant approach to pesticide risk assessment and management.