Cytogenetic effects of paraoxon and methyl-parathion on cultured human lymphocytes: SCE, clastogenic activity and cell cycle delay.

Paraoxon and methyl-parathion (Wofatox), frequently used organophosphate pesticides, were tested for cytogenetic effects in lymphocytes of persons with different phenotypes of paraoxonase activity. Sister chromatid exchanges (SCE), chromosome breaks, and cell cycle traverse were studied in ten individuals. Paraoxon showed no significant effects whereas methyl-parathion showed a dose-dependent increase in the SCE and a definite delay in the cell cycle as assessed by fluorescence plus Giemsa technique. No significant clastogenic effects and no difference in response were observed among individuals with different phenotypes of paraoxonase.