[Disorders of antioxidant defence and their correction in experimental di-isopropyl-phenyl-isocyanate intoxication]. / Narushenie protsessov antioksidantnoi zashchity i ikh korrektsiia v éksperimente pri intoksikatsii 2,6-diizopropilfenilizotsianatom.

Using preventively natural and artificial antioxidants in experiments on white rats enabled to assess role of lipids peroxidation in mechanisms of acute inhalation toxicity caused by 2,6-diisopropylphenylisocyanate. Correlation and regression analysis revealed differences in mechanisms underlying antioxidants effects.

[Prospects of the development of preventive toxicology in the 21st century]. / Perspektivy razvitiia profilakticheskoi toksikologii v XXI veke.

The national toxicology has created considerable theoretical potential to enter XXI century. Significant experience is associated with introducing the novelties. However, some circumstances inhibit environmental protection from chemical disorder. Those circumstances necessitate deviation to adjacent spheres of science and practice (though every deviation inevitably lower the scientist's efficiency). Chances are that common sense will overmatch current hurry, and prophylactic toxicology will cooperate with other branches to overcome de mographic crisis in Russia and to contribute into health preservation.

[The toxicological, hygienic and clinical aspects of the action of low levels of organic solvents]. / Toksikologicheskie, gigienicheskie i klinicheskie aspekty deistviia nizkikh urovnei organicheskikh rastvoritelei.

The article presents experimental data showing that Average Shift Concentration (ASC) and Maximal Single Concentration (MSC) for some solvents (tetrachloromethane, tetrachloroethane, dimethylformamide, benzene) are expedient to be justified. Clinical and hygienic materials proved significant health parameters (nervous system, peripheral blood) and urine levels of main metabolites to depend on chlorbenzene and toluene concentrations influencing the workers. Having analyzed the results, the authors recommended following hygienic norms in the air of workplace: for chlorbenzene ASC--50 mg/cu m, MSC--100 mg/cu m; biologic MAC for urine 4-chlorcatechol--0.05 g/l; for toluene ASC--50 mg/cu m, MSC--150 mg/cu m; biologic MAC for urine hippuric acid--1.5 g/l. The article shows some features of ASC and MSC practical application.

[Hygienic aspects of the regulation of occupational chemicals]. / Gigienicheskie aspekty reglamentatsii khimicheskogo faktora proizvodstvennoi sredy.

Hygienic regulation of chemical hazards in the air of workplace has a 70-year history in this country. Now a definition "maximal allowable concentration in the air of workplace" needs to be more precise, and a list of MACs should be modified.

[Materials for the substantiation of the biological MAC of benzene]. / Materialy k obosnovaniiu biologicheskoi PDK benzola.

Relatively great amount of benzene-originated phenol, the presence of a definite relationship between phenol amount in the urine and benzene content in the air indicate that it is reasonable to use a phenol sample as an exposure test. To determine the intensity of benzene exposure, data on phenol content in the urine of people working at some big-tonnage enterprises has been analyzed. On the basis of the national and foreign literature data on the correlation between the phenol urine concentration and the level of benzene exposure a regression equation was deduced, which has made it possible to calculate phenol content in the urine on the level of average working day benzene concentration adopted in the USSR. This value equals 15 mg/l, which was proposed as a biological benzene MAC.

[Use of quantitative chemical characteristics of phenol ethers in the prognostication of toxicity and MPEL in the air of work areas]. / Ispol'zovanie kvantovo-khimicheskikh kharakteristik éfirov fenola dlia prognozirovaniia toksichnosti i PDK v vozdukhe rabochei zony.

The contributors use the molecular orbital technique to present, with due account of the metabolism specificity, a quantitative description of the phenol ether inhalation toxicity and their reactivity calculated against the energy of the ether and OH- complex formation. Linear dependencies were identified between the acute and chronic action threshold, MAC and the quantum chemical values of the energy of formation. The dependencies were utilized for forecasting the toxicity and safe levels for 37 substances.

Application of toxico-kinetic criteria as a basis for toxicometric parameters.

In an experiment with single exposure to benzene and styrene at a level corresponding, to the threshold of harmful effect established by functional indices the intensity of metabolism was found to decrease. Toxico-kinetic characteristics of the substance in a single experiment permit us to prognosticate the risk of developing chronic intoxication. In comparison with indices characterizing general state of the organism, toxicokinetic indices enhance the reliability of toxicometric parameters used in determining Mac's for the air of the working area.

Results obtained in short-term experiments and their application prospects in prognosticating threshold levels of chronic exposure to chemical compounds.

Joint studies carried out by toxicologists of CMEA countries have led to the development of new ways of approach to the problem of rapid establishment of toxicometric parameters and hygienic standards (TSEL, MAC) for the working-zone atmosphere. One of the most promising approaches is the rapid establishment of MAC from the threshold of acute specific effect. Upon this principle, methodical directives for determining MAC values for specifically active irritants were elaborated. A study of the quantitative relations between toxicometric parameters and the physicochemical properties of substances in the working-zone atmosphere furnished methods for calculating TSEL values for noxious substances in this atmosphere. The essential possibility was confirmed of using isolated mitochondria as a model for preliminarily estimating the toxicity and establishing safe concentration levels of noxious substances in the working-zone atmosphere. The application of a complex of functional, biochemical and morphometric indices made it possible to foretell from short-term experiments minimal effective concentrations of a substance on chronic exposure. Ways of further research in the field of prognosticating toxicometric parameters and hygienic regulations for chemical compounds are outlined.

Intermittent exposure to toxic compounds in the working-zone atmosphere viewed from the aspect of hygienic standardization.

Four highly cumulative substances (carbon tetrachloride, 1,1,2,2-tetrachloroethane, benzene and dimethylformamide) were studied at two exposure levels under a monotonous and an intermittent exposure regimen in subacute experiments on rats. The biological effect produced by the intermittent concentrations as compared with the stable concentrations under time-weighted average concentrations depended both on the physiochemical properties and biological action of the poisons as well as on the exposure level. The intermittent concentration rises within certain limits (threefold as a rule) were injurious with some of the substances at a relatively high exposure level, but were not detrimental as compared with stable concentrations at a low exposure level. The other substances showed no difference between the effect of the monotonous and the intermittent regimens at either low or high exposure levels. The results of these studies form an experimental basis for a dual hygienic standardization: the establishment of maximum and average-shift admissible concentrations for the compounds studied as well as other highly cumulative substances.

Development of methodological approaches to the determination of safe levels of activity of harmful substances in the air of the working environment.

1. An experiment study was carried out to substantiate fundamental approaches to the determination of shift-average and maximum instantaneous concentration of highly cumulative substances in the air of the working environment. 2. The determination of maximum instantaneous concentrations in the air of the working environment is maintained for some groups of chemical compounds (irritant poisons, substances having acute effect, etc). An express, method of determining MAC in the air of the working environment has been developed for the purpose of hygienic norm-setting for irritant substances.