Introduction. High morbidity rates of diseases of the endocrine system and the existing features of drinking water pollution with organochlorine compounds (OCCs) make it necessary to study the mechanisms of the influence of low doses of organochlorine pesticides on public health. The purpose of the study is to study the features of the formation of non-carcinogenic risk in the population associated with exposure to OCCs in drinking water and endocrine disorders, using the example of 2,4-dichlorophenoxyacetic acid (2,4-D) under conditions of chronic oral exposure in small doses in the experiment. Materials and methods. According to the results of a comparative hygienic assessment of more than 10 thousand samples of drinking water from centralized water supply in 41 municipalities of the Orenburg region, a rural area with the highest content of OCCs and 2,4-D was identified. There was executed an analysis of the incidence of diseases of the endocrine system, digestive system and metabolic disorders (E00-E90) in the population. The experimental part of the work was carried out on 2 groups of Wistar rats: the 1st group was control, the 2nd group consumed water containing 2,4-DA (ammonium salt of 2,4-dichlorophenoxyacetic acid) at a concentration of 0.015 mg/l (0 .5 MPC). In the blood serum of animals, an analysis was made of the level of hormones: triiodothyronine (T3) and thyroid hormone (T4), testosterone and insulin, with an assessment of body weight and epididymal fat. Results. The observation area was established to be characterized by a high level of contamination of drinking water with OCCs and mainly with 2,4-D. Non-carcinogenic risk for the endocrine system (0.005), corresponding to an acceptable level, is significantly higher by 2-4 times (p < 0.05) for adults and children than in the comparison area. The primary incidence of diseases of the endocrine system, digestive system and metabolic disorders (E00-E90) in the observation area (34.88±5.9) is by 2 times higher than the average regional value and 6 times in the comparison area, which indicates the manifestation of disruptive properties 2,4-D and OCCs. The experiment showed that in animals of the experimental group, body weight on day 135 is 10% higher than the control one. An increase in the level of insulin in animals of the experimental group by 70% on day 45 and by 25% on days 90 and 135 of the experiment was established. In the experimental group, on the 45th, 90th and 135th days, the concentrations of T3 decreased by 22%, 5% and 6%, and T4 - by 13%, 12% and 38%, respectively. By the end of the experiment, the testosterone content in the experimental group was lower by 36%. Limitations. The limitations of the study are related to the transfer of the results of experimental data to the studied exposed population and the assessment of only OCCs and 2,4-dichlorophenoxyacetic acid (2,4-D) in drinking water without taking into account other environmental factors. Conclusion. The conducted study testifies to the manifestation of the disruptive properties of 2,4-D in an animal experiment, which is expressed by a violation of the mechanisms of metabolism regulation. The results of the experiment showed the intake of small doses (0.5 MPC) of 2,4-D into the body to have an obesogenic effect, manifested in a gain in total body weight and epididymal fat, accompanied by a decrease in the level of testosterone and thyroid hormones in the blood serum.

There was studied the effect of 6-weeks intake of small doses of the herbicide 2,4-DA on the body weight of animals. The consumption of water containing the herbicide in a concentration of 0.5 MPC was shown to have led to the greater gain of the body weight in experimental rats in comparison with the control. Simultaneously there was noted the gain of the mass of epididymal fat and increase in the concentration of leptin. This effect was more pronounced in rats treated with 2,4-DA, under the diet with high caloric content. The results obtained are likely to be associated with the disrupting action of the herbicide, leading, in particular, to the disturbance of the regulatory function of the thyroid gland and insulin resistance.

There were studied features of the manifestation of incoming with potable water nontoxic doses of the herbicide 2,4-D on the body mass index, some indices of lipid metabolism and immune system in different types of diets in the experiment in rats. There was shown a significant gain in body weight of animals, and MDA and leptin level in the serum under the action of a herbicide in conjunction with a high-calorie diet. In all experimental groups there was noted the increased level of total cholesterol, tendency to the increase of LDL cholesterol. Under the action of the herbicide there was noted an increase of IL-6, TNF-a and the numbers of leukocytes and, on the contrary, the reduction of the number of thymocytes and kariocytes in thymus and spleen.