Sub-Acute Exposure of Fenvalerate in Buffalo Calves:Toxicokinetic Evaluation

The effect of sub-acute fenvalerate administration on its toxicokinetics was studied in male buffalo calves. Four healthy male buffalo calves were administered fenvalerate orally (@ 1 mg.kg^-1.day^-1) for 21 consecutive days. On day one, blood samples were collected for upto 48 h post administration for toxicokinetic study. The calves were then drenched at the same dose rate for 21 days and sampling was repeated on 21^st day for toxicokinetic analysis. Concentrations of fenvalerate in the serum samples were analysed using gas chromatography (GC) and toxicokinetic parameters were calculated as per the non compartmental analysis. Significantly reduced distribution at steady state (0.11 L.kg^-1 Vs 0.19 L.kg^-1) on 21^st day of continuous exposure compared to day one, clearly indicated limited distribution of the pesticide in various body fluids and tissues upon repeated administration. There was improved persistence of toxicant in the body upon sub-acute exposure as shown by significant increase in area under curve (AUC=156.4 Vs 69.1 μg.h.ml^-1) after sub-acute administration. This fact was further supported by increased mean residence time (MRT=16.7 h Vs 12.6 h) of the pesticide. There was significant increase in the elimination half life (11.6 h Vs 8.74h) of the toxicant on day 21 compared to that observed on day 1, which was further underlined by a significant decrease in its clearance (0.006 Vs 0.015 L.kg^-1.h^-1). Sub-acute exposure of fenvalerate at the proposed dose rate resulted in limited tissue distribution, augmented persistence and slow elimination from the body of animals. This altered toxicokinetics of fenvalerate upon subacute exposure might be due to its effect on organs of metabolism and/elimination, thereby posing increased risk of toxicity in buffalo calves.