Sublethal chronic effects of oral dietary exposure to deltamethrin in Swiss albino mice

The hazards of dietary exposure to environmentally relevant levels of deltamethrin are poorly understood though studies enunciate the acute toxicity hazards. In this study, prolonged exposure to low levels of deltamethrin in mice was investigated. The mice were exposed daily via gavage method for 60 days. Four doses (0.1, 0.05, 0.01, and 0.005 mg/kg bwt/d) were selected, which are equal to or less than the maximum residue limits for deltamethrin permitted in animal food/feed. Liver, kidney, lungs, spleen, and testes were collected on day 61 for histology, residue, and biochemical analysis (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALKP), total bilirubin (TBIL), total proteins (TPs), cholesterol (CHOL), urea, and creatinine). No significant changes were observed in body weight gain in all treatment groups (p > 0.05). The gas chromatography analysis indicated that none of the tissue samples contained deltamethrin residues above the limits of quantification. The significant differences in biochemical profile (AST, ALT, TBIL, and creatinine) reported in animals exposed to 0.1 and 0.05 mg/kg bwt/d deltamethrin (p < 0.05) suggest respective tissue injury and lipid peroxidation; however, few significant changes in urea and CHOL were also reported in doses 0.01 and 0.005 mg/kg bwt. No significant differences in TP and ALKP were observed (p > 0.05). The target organs for deltamethrin toxicity showed prominent histopathological changes in concentrations of 0.1 and 0.05 mg/kg bwt. Other two doses showed no or sporadic changes. Our findings suggest that chronic exposure to environmentally relevant levels of deltamethrin can have detrimental effects on vital organs in the circumstances allowing daily exposure, in congruence with available literature.