Toxicity assessment of emamectin benzoate and its commercially available formulations in Pakistan by in vivo and in vitro assays

Abstract

Emamectin benzoate (EMB) is generally considered a safe insecticide in agriculture and veterinary practices, yet, it can cause cytotoxic and genotoxic effects. Hence, the aim of this study was to evaluate toxic effects of 80% EMB and its commercially used formulations (Tycon 1.9% EC and Tycon plus 5% EW) in Pakistan and tested for acute toxicity in albino rats, rabbits and fish (Labeo rohita). Genotoxicity was investigated by in vivo comet assay and bone marrow micronucleues test in the rats. In vitro mutagenicity was tested in Salmonella typhimurium TA98 and TA100. The tested EMB formulations were found moderately toxic (oral LD₅₀: 122-168 mg/kg), causing severe eye irritation in rabbits, highly toxic to fish (LC₅₀: 9-43 μg/L) and found non mutagenic. Oral administrations of EMB (80% and 5%) at 100 mg/kg of body weight to male rats reduced red blood cells, hemoglobin, and slightly increased the blood glucose, urea and liver enzymes levels but had no significant damage to DNA. EMB induced bone marrow toxicity was observed as reduction of polychromatic erythrocytes. Overall, EMB exposure was highly toxic to fish, and caused hemo- and hepatotoxicity in rats. These findings warrant cautious use of EMB formulations in agrochemicals and veterinary medicine.

Keywords: Acute toxicity; Biopesticide; Emamectin benzoate; Genotoxicity; Tycon 5%.