The analysis of markers enzymes activity changes of subcellular organells in pre-school children residing in the chemical centre - the town of Sterlitamak, was carried out in ecotoxicants effect condition. The increased level of free malatedehidrogenase activity in relation to the control (by 2 - 2,5 times), microsomal acethylesterase (by 1,4 times), β-galactosidase (by 3 - 6 times) was detected in the blood of the children living closest to the industrial area. The investigation has shown lipoperoxidation induction in urine (malondialdehyde content was increased by 1,3 - 2,2 times as well). On the whole the changes revealed show membranotropic effect and cytopathogenic action of chemical factors on the organism. The latter support the results of cytogenetic analyses of the adult population: increased chromosome aberations frequency - 4,6 % among the employees of chemical plants (15 people) and 3,9 % (10 people) in the control group which testifies to increased genotoxicity level (top border limit being about 3 %).