One of the complex problems of modern experimental toxicology remains the molecular mechanism of formation of human health disorders separated at different time periods from acute or chronic exposure to toxic environmental pollutants (ecotoxicants). Identifying and understanding what epigenetic changes are induced by the environment, and how they can lead to unfavorable outcome, are vital for protecting public health. Therefore, we consider it important a modern understanding of epigenetic mechanisms involved in the life cycle of mammals and assess available data on the environmentally caused epigenetic toxicity and, accordingly fledging epigenenomic (epigenetic) regulatory toxicology.

Keywords: epigenetics, epigenomics, epigenetic mechanisms, toxicoepigenetics, epigenetic changes in early development, DNA methylation, bisphenol A, cadmium chloride, human cell cultures, chromosomes, chromatin, intergenerational inheritance of epigenome after exposure to tox

A study of the dynamics of preservation of the conditioned reflex of passive avoidance (passive avoidance response) in rats of two lines with different level of excitability of the nervous system was performed: with a high and low thresholds of excitability as normal and after exposure to sodium thiopental semi-lethal dose. It was shown that a long preservation of the memorable trace under standard conditions and a higher sensitivity to the sodium thiopental action manifest in rats with a high excitability threshold in comparison with low-excitable line of rats.

Keywords: sodium thiopental, conditioned reflex of passive avoidance, excitability

Water containing polyvinyl nitrate was experimentally assessed on the basis of organoleptic, general sanitary and toxicological indicators of harmfulness. It was established that that the compound did not change water organoleptic properties but produced a negative impact on viability of saprophytic microflora , nitrification processes and biochemical oxygen demand. Besides, in tests on animals. the substance caused acute, sub-acute and chronic toxicity. Based on those signs of harmfulness, threshold levels of exposure were established. Data obtained were taken into account for substantiation of MAC (Maximum allowable concentration) of polyvinyl nitrate in water bodies.

Keywords: water, poly vinyl nitrate, sanitary mode, in water bodies, general toxic action, threshold level

The modern technique for the determination of 2,4-D, that belongs to global environmental pollutants, including the use of the technology of sample preparation - dispersive solid-phase-liquid extraction (QuEChERS), new for products of animal origin, has been developed. The sample preparation procedure includes the steps of: preliminary freezing of the sample to be analyzed, extraction with acetonitrile containing 1% acetic acid in the presence of MgSO4 and NaCl, purification by dispersive solid-phase extraction using a mixture of sorbents based on primarysecondary amine, octadecylsilane and graphitized carbon black, the freeze of the solution - at the last stage. Using the proposed technique allows to isolate the desired component from a matrix with a high content of animal fat into a selected organic solvent with high efficiency, that made it possible to expand significantly the arsenal of analytical equipment used to detect residual amounts of 2,4-D in food products of agricultural production, for example milk, eggs and offal (liver, kidney): tandem liquid mass-spectrometry (HPLC-MS/MS), gas-liquid chromatography with mass-selective and electron-capture detectors (GLC-MSD, GLC-ECD). The lower limit of the quantitative determination is 2,4-D: 0,005 mg/kg for milk and eggs, 0.05 mg/kg for the liver and kidneys. Completeness of extraction is 85-94%, RMS of repeatability is 3,4-11,4%.

Keywords: sample preparation, liquid and gas-liquid chromatography, 2, 4-D, products of agricultural production

Changes in the histogram of the midgut in bees exposed to lead and cadmium salts polluting their carbohydrate feed was studied. Normally , the mitgut is composed of the mucosa and muscular membranes separated with a thin layer of the basal membrane. The muscular membrane that forms the outer wall is a layer of cross-striated muscle symplasis intersecting in mutually perpendicular directions. On the mucous side, the muscular layer is delimited by a basal membrane and its outer side freely connects with internal environments of the abdominal region. Specific signs of lead poisoning manifest in the development of total and sub-total coagulative necrosis of the midgut mucous membrane. Its lesion in poisoning with cadmium is characterized by dystrophy expressed in cytoplasmic micro vesiculation which is followed by desquamation of the mucous membrane and destruction of glandular crypts.

Keywords: honey bee, mtdgut, histogram, poisoning with lead and cadmium salts

Although the total content of organic s compounds in water is regulated, it is rather difficult to formulate and set standards for individual organic substances coming to the biological treatment facilities of urban aeration stations. Many experts believe it necessary to conduct further experimental studies to set their permissible concentrations and prevent slowing down biological treatment. One of the accepted experimental control methods for toxicity is a bio testing method. In the course of the present study, an investigation into ampicillin toxicity was performed for the test-objects daphnia and community of microorganisms in active silt. The experiment was carried out on crustaceans using N.S. Stroganov standard technique. The impact of antibiotics on active silt was assessed by changes in the microorganisms’ dehydrogenases activity. The research results allow to characterize ampicillin as very low toxic to Daphnia and to active silt community of microorganisms , toxic effect of the antibiotics was established in concentrations of 200 to 400 mg/l.

Keywords: ampicillin, toxicity, daphnia, activated sludge, dehydrogenase

Strain B. thuringiensis ssp. toumanoffi 25 does not have sensitizing properties, does not affect the cellular and humoral parts of the immune system, the intestinal microflora. The MAC of the strain in the air of the working area is recommended at 5x104 mg/m3, in the atmospheric air of residential areas it is 5x103 mg/m3.

Keywords: B. thuringiensis ssp. toumanoffi 25, sensibilization, MAC

Approaches to the evaluation of toxicity and hazard of unstable substance bis(cyclopentadienyl) magnesium MAGNESOCENE (Cp2Mg)) are presented . The toxicity of the substance is determined by its main transformation products -magnesium oxide, magnesium hydroxide and cyclopentadiene. Due to the instability of the substance (it exists only in an inert environment) it is not possible to conduct studies on its sensitizing effect ,its reprotoxic, teratogenic, mutagenic and carcinogenic action on the organism. Control of the unstable compound bis (cyclopentadienyl) magnesium in the air of the working area and human habitat should be based on its transformation products: magnesium oxide and cyclopentadiene.

Keywords: toxicity, substance, transformation