Emamectin benzoate (EMB) is the active ingredient of Proclaim^®, a biopesticide extracted from the actinomycete soil microorganism Streptomyces avermitilis. Subchronic toxicity testing was performed in order to determine its potential effects on some selected blood parameters and histopathology of kidney of rats.

Emamectin benzoate was administered orally to male Wistar rats at doses of 5 (low) and 10 (high) mg/kg/day for 45days. Plasma samples at 28 and 45days were used to determine glucose, urea, creatinine, uric acid, direct and total bilirubin, albumin, ASAT and ALAT, as well as acetyl- and butyrylcholinesterase activities. The residual concentrations of emamectin benzoate mixture B1a and B1b were determined by UPLC–MS/MS.

A decrease in body weight after 45days of treatment and a significant increase after the post-treatment period were observed in the EMB high dose group. Treatment with EMB did not affect the mean weight of most organs. There were decreases in acetylcholinesterase and butyrylcholinesterase activities and a significant (P<0.05) increase in glucose, uric acid, total bilirubin, albumin levels, ASAT and ALAT activities, in rat plasmas after 28 and 45days of EMB exposure. Plasma EMB, B1a and B1b, were clearly detected after 28 and 45days. Our histological results showed congestion and dilation of proximal and distal tubules at low dose and inflammatory cell invasion, tissue congestion and vacuolization in tubular cells at high dose.

Taken together, these results suggest that the subchronic exposure to emamectine benzoate affects the renal function and alters plasma biomarkers of neurological and liver functions in Wistar rats.