Aim: The aim of this study was to assess the acute toxic interaction and lethal dose (LD₅₀) of pesticide combination product (acephate 50% and imidacloprid 1.8% as active ingredients) available in the market in Sprague-Dawley female rats by oral route.

Materials and Methods: A total of 10 Sprague-Dawley female rats were divided into two groups, comprising five rats in each dose group. Both groups were identified as control and test groups, respectively. Control group received sterile water as vehicle and test group received pesticide combination (acephate 50% and imidacloprid 1.8% as active ingredients) at a dose of 0 and 2000 mg/kg body weight. As per the Organization for Economic Cooperation and Development Guideline 420, initially one animal each from both the control and test groups were dosed with 0 and 2000 mg/kg, respectively, as sighting study. Based on the results of sighting study, additionally, four animals each from both groups were dosed with the same dose to make a total of five animals in each group. Dose volume was constant as 10 mL/kg. All animals were observed daily twice for clinical signs and mortality. Body weight was recorded on day 0 and weekly thereafter during 14 days' observation period; last body weight (fasted) was recorded on day 15. All the rats of both the groups were humanely sacrificed on day 15 for gross pathology, collection of organs for histopathology, organ weighing, and morphometry. Organ weights were taken as absolute values, and relative organ weights to last fasted body weights were calculated.

Results: Pesticide combination (acephate 50% and imidacloprid 1.8% as active ingredients) treated rats showed cholinergic signs with one mortality in the test group. No significant difference was observed in body weight, relative organ weights, and organ morphometry between pesticide combination exposed and non-exposed groups. Gross pathology of the treated rats was also comparable with respect to control group. Histopathological changes in the liver, kidneys, heart, lung, adrenaline, spleen, and ovaries of test group rats were found to be comparable with control group rats.

Conclusion: The present study demonstrated the LD₅₀ of one of the combination products available in the market having acephate 50% and imidacloprid 1.8% as active ingredients in Sprague-Dawley female rats which is >2000 mg/kg body weight. Furthermore, gross, histopathology and histoarchitectural alterations of all the vital organs of the test group were comparable to the control.

Keywords: acephate 50%, acute oral toxicity, histopathology, imidacloprid 1.8%.

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