Assessment of the immune-developmental toxicity risk of the hygienic insecticide dimefluthrin in zebrafish (Danio rerio) model.

Abstract

Hygienic insecticides play a key role in the prevention of vector-borne diseases and are closely related to human health. Pyrethroids have become widely used household hygienic insecticides following restrictions on organophosphorus insecticides. Given that increased mosquito resistance had brought to the fore the misuse of hygienic insecticides, understanding the immunotoxicity risks of hygienic insecticides is essential for future risk management. The present study provided a comprehensive assessment of the immunotoxicity of dimefluthrin, one of the hygienic insecticides with the highest percentage of international use. After exposure to dimefluthrin at different doses (0, 0.2, 0.4, 0.8 μg/mL) for 72 h, it was shown that dimefluthrin induced intestinal developmental malformations and inflammation. Zebrafish exposed to 5 μg/L dimefluthin for 30 days developed an increase in pathogenic bacteria and a decrease in beneficial bacteria in the gut. Exposure to dimefluthrin impeded the formation of intrinsic immune cells (neutrophils, macrophages) and adaptive immune cells, T lymphocytes (T cells), and their migration and phagocytosis were impaired. Additionally, dimefluthrin markedly reduced the zebrafish's resistance to external tumor stimuli, inhibited the respiratory burst of leukocytes, and ultimately affected the immune response. This study implied that exposure to hygienic insecticides might pose potential immunological risks.