IN-VITRO AND IN-VIVO GENOTOXIC ACTIVITY OF MIRAL, AN ORGANOPHOSPHORUSINSECTICIDE USED IN COLOMBIA

Miral(R) 500 CS (CAS# 42509-80-8), an organophosphorus insecticide, ha s been widely used in Colombia to fumigate coffee plantations. Therefo re, there is extensive human exposure to this pesticide. Miral's mutag enic and genotoxic activities, however, are not known. In this study, such activities of the pesticide were evaluated using the Salmonella T A98/S9 test and the chromosome aberration assay in bone marrow cells o f Swiss albino CD1 male mice. All doses tested with Salmonella in the presence of S9 mix (3.2, 16, 80, 400 and 2000 mu g/plate) induced a mu tagenic response that was three times the spontaneous mutation frequen cy. The mutagenic response without S9 was twice the spontaneous freque ncy. Based on a 4-day treatment (i.p.) of mice with Miral, the median lethal dose (LD50) and the maximum tolerated dose (MTD) were 912.5 mg/ kg and 730 mg/kg, respectively. A significant dose-dependent cell cycl e delay (r(2) = 0.85, p < 0.01) was observed in bone marrow cells when mice were treated for 24 h with 73, 146, 219, 292, 365, 438, 511, 584 , 657 and 730 mg/kg. Significant increases in mitotic indices (p < 0.0 2) and chromosome aberrations (p < 0.05) were induced in bone marrow c ells, when mice were treated for 18 h with the highest dose 511 mg/kg. Our results indicate that Miral is a mutagenic compound in Salmonella and is capable of inducing chromosome aberrations at high doses in mi ce. Additional genotoxicity studies in farmers exposed to Miral should be conducted to determine the potential human health risk resulting f rom chronic low-dose exposures to this pesticide. (C) 1998 Elsevier Sc ience B.V. All rights reserved.