[Carcinogenic hazard of chloroform and other drinking water chlorination by-products].

The paper presents the results of studying the carcinogenic effect of chloroform and its combination with carbon tetrachloride, 1,2-dichloroethane, trichloroethylene during chronic oral administration to F1(CBAxC57Bl6) mice. There is a relationship between the manifestation of carcinogenesis to the dose of chloroform and a combination of chemicals, as well as its enhancement upon exposure to the combination as compared with acute administration of chloroform. Exposure to a combination of substances at the level of their maximum permissible concentrations does not affect carcinogenesis. The possible mechanisms of the specific features of carcinogenesis in this experiment are discussed.

[Setting normal levels of benz(a)pyrene in foods]. / Normuvannia vmistu benz(a)pireny u produktakh kharchuvannia.

In the paper, methodological requirements are formulated for validation of permissible levels of benz(a)pyrene (B(a)P) in foodstuffs. A list is submitted of allowable levels of this carcinogen in food products for the population of Ukraine, their specific values being dependent on the accepted tolerance daily done intake and on the structure of the standard food ration. Prevention of B(a)P formation and its elimination from the human habitat together with the use of the modern environmentally appropriate technologies designed to prepare food products will form a basis for stabilization of the permissible dose of the carcinogen, finding its way to the human body as a food component through dietary intake.

[Methodological issues of standardization of environmental carcinogenic agents]. / O metodologicheskikh voprosakh normirovaniia khimicheskikh kantserogennykh veshchestv v okruzhaiushchei srede.

The paper considers the basic methodological principles for standardization of environmental carcinogenic agents. It shows it necessary to take into account carcinogenic hazards presented by environmental chemical pollutants. Emphasis is laid to the standardization of these substances in terms of the combined and complex action.

[Oncologic hygienic aspects of regulation of benz(a)pyrene in food products]. / Onkogigienicheskie aspekty reglamentirovaniia benz(a)pirena v produktakh pitaniia.

The paper presents a methodological scheme for regulating the acceptable levels of benz(a)pyrene in the foodstuffs is presented. It also gives a list of the acceptable levels of this carcinogen in the foodstuffs whose specific values depend on its daily dosage and the pattern of a standard diet for the Ukraine's population.

[Hygienic aspects of the study of the synthesis of nitrosamines from their precursors]. / Gigienicheskie aspekty izucheniia sinteza nitrozaminov iz ikh predshestvennikov.

The paper presents data on the content of nitrosamines (NA), such an nitrosodimethylamine, nitrosodiethylamine, and their precursors (NO2 and amines) in the ambient air of different functional zones of a city. A high correlation between NA and NO2 in the air was established. NO2 was shown to have the leading role as a nitrosating agent in the model system and air during exogenous synthesis. The findings support the possible endogenous production and the role of NO2 in this process.

Peculiarities of carcinogenesis under simultaneous oral administration of benzo(a)pyrene and o-cresol in mice.

A modifying influence of ortho-cresol (o-cresol) on the carcinogenic effect of benzo(a)pyrene (BaP) with combined oral administration to CC57Br mice had been found. During simultaneous administration of o-cresol (1 mg) and BaP (1 mg), the incidence of tumors, the multiplicity of tumors, and the degree of malignancy all increased, but the latency was shortened. When o-cresol was administered before or after BaP (in identical doses), the carcinogenic effect was weakened. When o-cresol (10 mg) and BaP (5 mg) were administered simultaneously, the incidence of malignant tumors was similar to controls receiving BaP only (13.8%), indicating inhibition of carcinogenesis.

[Experimental study of combined effects of benzo(a)pyrene and ortho-cresol on the body]. / Eksperimental'noe izuchenie kombinirovannogo deistviia benz(a)pirena i ortokrezola na organizm.

Ortho-cresol (o-cresol) produces a modifying influence on the effect produced by benz/a/pyrene (BP) under mice CC57B exposure to the combined peroral administration of the two chemicals. A low-toxic dose of o-cresol (Img) abruptly activates the effect of the same dose of BP (1 mg) according to all parameters (increase of the frequency, coefficient of multiplicity and degree of malignancy of tumours, shortening of the latency period) and somewhat inhibits its activity when administered before or after BP. Simultaneous administration of o-cresol in a ++super-toxic dose (10 mg) and BP in an optimal dose (5 mg) does not change the frequency of tumours, as compared to the control, however, inhibits the progression of induces neoplasms, which is manifest in the decrease of the frequency of malignancy, multiplicity of appearance and lengthening of the time of the onset of their malignization. Simultaneous administration of o-cresol in the dose relevant to the MAC for water does not change the carcinogenic activity of BP, which testifies to the necessity of sanitary control of observing hygienic regulations for both chemicals, as the most effective measure of prophylaxis of the malignant tumours morbidity of the population.

[Experimental substantiation of MPEL of dibenz(a,n)anthracene in atmospheric air]. / Eksperimental'noe obosnovanie PDK dibenz(a,n)antratsenav atmosfernom vozdukhe.

Overt dependence of lung tumour development on the values of the dose administered was shown in experiments on inbred white rats under intratracheal administration of various doses of dibenz (a, h) anthracene (DBA); minimal-effect dose and maximal no-effect dose of DBA were established in the experiment. A theoretically calculated allowable dose was used to calculate MAC of the chemical under study for the ambient air 5 ng/m3 was recommended as an average 24-hour maximum allowable concentration of DBA in ambient air.

[The modifying effect of ortho-cresol on benzo(a)pyrene-induced carcinogenesis in mice]. / Modifitsiruiushchee vliianie orto-krezola na kantserogenez, indutsirovannyi benz(a)pirenom u myshei.

A modifying influence of ortho-cresol (o-cresol) on the carcinogenic effect of benzo(a)pyrene (B(a)P) in their combined peroral administration to CC57Br mice has been revealed. During the simultaneous administration of the o-cresol (1 mg) and B(a)P (1 mg) the rate of tumours, their multiplicity index, the degree of malignancy increased and the latent period shortened. In case of o-cresol administration before or after B(a)P (in the same doses) the decrease of carcinogenic effect has been revealed. In case of simultaneous administration of 10 mg of the o-cresol and 5 mg of the B(a)P the tumor incidence did not change in comparison with the animals of the control group which received only B(a)P. But their progression was hampered which was confirmed by a decrease of the malignancy rate, frequent occurrence and prolongation of the period of the malignization beginning.

[Kinetics of metallo-enzymatic paramagnetic centers and free radicals in the rat liver in lung carcinogenesis]. / Kinetika metallofermentnykh paramagnitnykh tsentrov i svobodnykh radikalov v pecheni krys pri kantserogeneze legkikh.

Kinetics of the content of nonheme iron-sulphur-containing (iron-sulphur) proteins, free radicals of electron-transport mitochondrial system, as well as of microsome terminal oxidase cytochrome P-450 is studied in the liver of rats at early stages of carcinogenesis and in the process of tumour growth induced by intratracheal administration of various benz(a)pyrene doses. It is found that the content of iron-sulphur proteins increases after the first administration, then it falls against a background of higher concentration of free radicals. A degree of pronounced changes in the content of the studied iron-sulphur proteins correlates with carcinogen dose. The cytochrome P-450 content is lowered for almost the whole period of carcinogen administration. In later periods animals with morphologically determinable pretumour changes exhibit a much higher content of iron-sulphur proteins, somewhat increased concentration of free radicals and a tendency to an increased level of cytochrome P-450. The appearance and growth of malignant tumours is followed by a considerable decrease in the content of iron-sulphur proteins and cytochrome P-450. On the basis of the results obtained it is supposed that the changes in the content of iron-sulphur proteins in the rat liver is the earliest and most pronounced reaction which depends on the benz(a)pyrene dose and may be of prognostic significance.