Neurotoxic Effects of Pyrethroid Insecticides: Mechanisms, Health Risks, and Future Perspectives

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ABSTRACT

Pyrethroid insecticides, synthetic derivatives of natural pyrethrins, are widely used in agriculture and public health due to their potent insecticidal properties and relatively low mammalian toxicity. However, emerging evidence highlights their neurotoxic potential, raising concerns about human and environmental health. This review comprehensively examines the mechanisms of pyrethroid toxicity, focusing on their interaction with voltage-gated sodium, calcium, and chloride channels in neuronal membranes. Pyrethroids prolong sodium channel activation, leading to repetitive nerve firing, hyperexcitation, and, in severe cases, seizures or paralysis. Additionally, they disrupt calcium homeostasis and inhibit chloride channels, exacerbating neurotoxic effects. These compounds are classified into Type I (non-cyano) and Type II (α-cyano) pyrethroids, each eliciting distinct neurotoxic syndromes—T-syndrome (tremors) and CS-syndrome (choreoathetosis-salivation), respectively. While adult mammals exhibit lower sensitivity due to differential sodium channel isoforms, developing organisms are particularly vulnerable, with prenatal and childhood exposure linked to cognitive deficits, developmental delays, and behavioral disorders. Beyond neurotoxicity, pyrethroids disrupt endocrine function, impair reproductive health, and induce organ damage, particularly in the liver, heart, and kidneys. Occupational exposure in agricultural workers and environmental contamination further amplify public health risks. Despite regulatory restrictions on certain pyrethroids, their widespread use persists, necessitating further research into long-term low-dose exposure effects and safer alternatives. This review synthesizes current knowledge on pyrethroid neurotoxicity, emphasizing the need for enhanced regulatory policies, advanced neuroprotective strategies, and sustainable pest control solutions to mitigate health risks.

Significance of the Study:

This study provides critical insights into the organ-specific toxicity of pyrethroid insecticides, demonstrating their potential to cause liver, heart, and kidney damage through oxidative stress, inflammation, and metabolic disruption. The findings highlight the risks associated with different exposure routes, particularly inhalation, and underscore the need for revised safety assessments. The research is vital for policymakers, healthcare providers, and occupational safety regulators to implement protective measures, especially for vulnerable populations and those with chronic exposure.

Summary of the Study:

Histopathological analysis revealed that pyrethroid exposure induces significant liver necrosis, cardiac atrophy, and renal tubular damage in animal models. Mosquito coil smoke caused the most severe toxicity, while antioxidant treatments showed partial protection. The study confirms pyrethroids’ multi-organ toxicity through oxidative stress and metabolic dysfunction, emphasizing the need for stricter exposure guidelines and alternative pest control strategies to mitigate long-term health risks in humans and wildlife.