Cytogenetic effect of the thiocarbamate herbicides butylate, molinate and vernolate in the mouse bone marrow micronucleus test.

Three thiocarbamate herbicides, butylate (S-ethyl-diisobutylthiocarbamate), vernolate (S-propyl dipropylthiocarbamate) and molinate (S-ethyl-N,N-hexamethylenethiocarbamate) were assayed for cytogenetic effect in the mouse bone marrow micronucleus test. Butylate was inactive in bone marrow, vernolate caused a marginal increase in the incidence of micronucleated polychromatic erythrocytes only at a high toxic dose level. Molinate, the N,N-hexamethylene derivative was, however, strongly active in the bone marrow, causing a high frequency of micronucleated erythrocytes, even at subtoxic concentrations.

Long-term carcinogenicity bioassay of the herbicide atrazine in F344 rats.

In Fischer F344/LATI rats of both sexes the herbicide atrazine was given in the diet at concentrations of 0, 375 and 750 ppm for 126 weeks. Food and water consumption was similar in the treated and control groups. Feeding of atrazine resulted in dose-dependent depression of body weight gain in both sexes. There was no difference in the survival among the females. The males in the treated groups lived significantly longer than the controls. Exposure to atrazine resulted in significantly increased incidence of mammary tumors in the high dose male group. Uterine carcinomas were observed at a dose-related, significantly increased incidence. The number of combined leukemias/lymphomas increased in the treated males and females, but it was statistically significant only for females. The total number of malignant tumors showed a dose-related increase in both sexes. Other tumors and nontumorous lesions occurred at background level and were not influenced by treatment.

Mutagenicity of emission and immission samples around industrial areas.

Urban air particulates (suspended particles and settling dusts), as well as dusts emitted by a Söderberg aluminium production plant and a coal-burning power plant, in the industrial town of Ajka were analysed for polycyclic aromatic hydrocarbon (PAH) content (liquid chromatography) and mutagenicity (Salmonella microsome test). The same parameters for air particulates from Pápa (a town of similar size without much heavy industry) were analysed and compared to those from Ajka. The dust content, PAH concentration and the mutagenic potency of the air in Ajka were higher than in Pápa. Mutagenicity of airborne particulates showed a clear seasonality with a winter maximum and a summer minimum in both towns. The mutagenic potency of air correlated well with the benzo[a]pyrene (BP) and PAH content in Ajka but not in Pápa. The amounts of extractable organic material and mutagenic potency, as calculated for unit quantity of airborne particulate matter, were higher in the Pápa samples. Similar differences between the two towns were observed in the case of deposited dust. As regards the emission dusts, the aluminium plant emissions are responsible for much more of the mutagenicity of the urban air than the power plant emission, which is the main component of air dust pollution in Ajka.

Analysis of genotoxic activity of 16 compounds and mixtures by the Drosophila mosaic test.

The mutagenicity of 16 compounds and mixtures were tested by the Drosophila melanogaster wing mosaic test. Fourteen of them gave negative results, two proved to be mutagenic. The positive compounds were chlor-diamino-toluene and 2-(2,4-dichlorophenoxy) propionic acid. Chlor-diamino-toluene increased the frequency of mitotic recombinations and gene mutations although it was found negative by the sex linked recessive lethal test. 2-(2,4-dichlorophenoxy) propionic acid caused only mitotic recombinations.

Genotoxicity of selected herbicides.

Twenty-two herbicides were studied in 67 tests for induction of DNA damage, gene mutation and chromosomal changes in vitro and in vivo. Triazine and urea-type herbicides were found to be inactive in all but one test. Of 4 thiocarbamates, molinate and vernolate caused chromosomal changes, namely increased incidence of sister chromatid exchanges and chromosomal aberrations in vitro and increased frequency of micronucleated polychromatic erythrocytes in mouse bone marrow. These compounds, however, did not cause gene mutation and only molinate gave equivocal positive result in bacterial repair test. Out of 11 miscellaneous herbicides, ethofumesate, alachlor, dichlorprop and fluorodifen proved to be positive only in one or two tests. In the light of clastogenicity of some thiocarbamates, serious consideration should be given to start animal carcinogenicity studies with these chemicals.

Mutagenicity and PAH content of airborn particulates and of fallen dusts from two Hungarian towns and emission samples from aluminum reduction and power plants.

Urban air particulates (suspended particles and settling dust), furthermore dust emitted by a Soderberg aluminum reduction plant and a coal burning power plant from an industrial town, Ajka (30,000 inhabitants) were analysed for PAH content (liquid chromatography) and mutagenicity (Salmonella microsome test). Air particulates from Papa--a town of similar size without considerable heavy industry--and corresponding plant emission from Inota, a third town in the study, served as controls. The dust content and the PAH concentration, as well as the mutagenic potency of the air in Ajka were higher than in Papa. Mutagenicity of the airborne particulates showed a clear seasonality with a winter maximum and a summer minimum in both towns. The mutagenic potency of air correlated well with the air BaP and total PAH content in Ajka, but not in Papa. The amounts of extractable organic material and mutagenic potency as calculated for unit quantity of airborne particulate matter was higher in the Papa samples. Similar differences between the two towns were observed in the case of fallen dust, too. On the basis of examination of emitted dust, it can be stated, that in the mutagenicity of urban air, the aluminum plant emission plays a considerably higher role than the power plant emission, which is the main component of air dust pollution in Ajka.

Mutagenicity studies on terbacil, an uracil-analogue pesticide.

The possible mutagenic effect of the uracil analogue pesticide Terbacil was examined on Drosophila melanogaster and in mammalian cell culture. Terbacil did not prove to be mutagenic in the sex-linked recessive lethal mutation test, and it did not cause an increase in sister chromatid exchange in CHO cells. It cannot be considered a chromosome-mutagenic compound. Considering the procaryote studies known from the literature, it is assumed that Terbacil does not represent a genotoxic hazard for the persons involved either in its production or its use.

Analysis of the genotoxic activity of four N-nitroso compounds by the Drosophila mosaic test.

Mutagenic activity of 4 nitroso compounds of environmental importance - N-nitroso-morpholine, dinitrosopiperazine, N,N'-dinitroso-pyridinol-carbamate and N-methyl-N-nitroso-p-toluenesulfonamide - was tested by the Drosophila mosaic test. Larvae were fed with the nitroso-compound-containing food for 2-4 days, and when they had developed into adults, their wings were screened for mosaic spots. All 4 compounds were positive. This finding supports the conclusion that the mosaic test - besides other test procedures - may become a tool for identifying mutagens.

Agriculturally-related carcinogenic risk.

Although all people are exposed throughout life to pesticides (during manufacture and use, in the environment, via the food chain), with the exception of vinyl chloride and the arsenic compounds, no human carcinogen pesticide is known. In experimental animals and short-term tests, however, many pesticides have proved to be carcinogenic or genotoxic. In order to elucidate possible modes of action related to genotoxicity (short-term tests) and carcinogenicity, data on 83 pesticides were analysed. A definitive promoter effect was demonstrated for five compounds, and a suspected promoter effect could be attributed to 16 compounds. Almost all were organohalogens. Ethylenthiourea and aminotriazole are also carcinogens, which induce tumours through hormonal imbalance. Ethylenthiourea is the degradation product and metabolite of certain ethylene-bisdithiocarbamate pesticides. Chlorphenol and chlorophenoxyacetic acid-type pesticides contain 2,3,7,8-tetrachlorodibenzo-paradioxin (TCDD) as a contaminant. TCDD has definite promoter action. Seventeen tumorigenic pesticides could be regarded as genotoxic, and similar activity could be suspected in three other carcinogenic pesticides. Many pesticides contain N-nitroso impurities in various amounts. Nitrosation of the original pesticide or its derivative, such as dialkylamines, alkyl-arylamines, methyleneimines, gives rise to the formation of N-nitroso compounds. Amides containing secondary amines, such as ethylcarbamate and alkylurea, could be nitrosated in vivo and in vitro. Most nitrosated pesticides are strong genotoxic carcinogens.

Inhibition by an antioxidant of the carcinogenic effect of nitrosomorpholine formed in vivo.

In earlier studies, it was found that the new antioxidant, MTDQ-DA ((6,6-methylene-bis)2,2-dimethyl-4-methane-sulphonic acid sodium salt-1,2-dihydroquinoline) (Patent No. 3172) prevented in vivo nitrosation and the acute hepatotoxicity of morpholine plus sodium nitrite in rats. The aim of the present experiments was to examine whether MTDQ-DA could decrease the frequency of tumours induced by simultaneous administration of morpholine and nitrite in the lung adenoma assay. Forty CFLP mice were used in each group and they were killed 8 months after treatment. In group A, treated with 1000 mg/kg morpholine i.g., and in Group B (untreated control) a similar frequency of lung adenomas could be observed (0.13 adenomas/mouse). After the combined i.g. treatment in Group C (MOR, 1000 mg/kg + nitrite, 125 mg/kg), the incidence of lung adenomas was found to be 16.58/mouse. A single dose of MTDQ-DA (500 mg/kg) added to the group C treatment reduced the lung adenoma frequency to 2.47/mouse (Group D). As MTDQ-DA shows neither toxic nor mutagenic effects and inhibits the in vivo nitrosation in both hepatotoxicity and lung adenoma assays, it may be considered to be a potential food additive.

Protective effect of a new antioxidant on acute hepatotoxicity caused by morpholine plus nitrite in rats.

Bis(2,2-dimethyl-4-methane sulphonic acid sodium salt-1,2-dihydroquinoline)-6,6'-methane (MTDQ-DA), a new, non-toxic, water soluble antioxidant, is shown to inhibit liver necrosis induced in rats by N-nitrosomorpholine (N-MOR), itself formed in vivo following the administration simultaneously of morphine (MOR) and sodium nitrite (NaNO2).

Endogenous formation of N-nitrosomorpholine from a new fungicide.

Trimorphamide [N-(1-formamido-2,2,2-trichloroethyl)morpholine], with an acute LD50 of 990 mg/kg, is a systemic fungicide under development. To examine its possible nitrosation in vivo, CFY rats were treated i.g. with 326 mg/kg trimorphamide, suspended in 40 mg/kg sodium nitrite. after 1 hour, another 40 mg/kg sodium nitrite was given i.g. and the animals were killed an hour later. The nitroso derivative was extracted by dichloromethane from the gastric content, after steam distillation. The samples were analysed by gas chromatography (GC) and mass spectrometry (MS). N-Nitrosomorpholine (NMOR) was identified by comparison with authentic samples, both by GC and MS, using retention times and electron impact mass spectra. Quantification was carried out by GC-MS-specific ion monitoring, using the m/e 116 peak. The yield of NMOR ws found to be 0.65%. By the use of the Ames test, NMOR formed in vivo proved to be strongly mutagenic for the strains TA 1535 and TA 100, both in presence and absence of S-9 fraction. Tumour-bearing animals, treated by sodium nitrite plus trimorphamide, are being analysed.

Mutagenicity of N-nitroso pyridinol carbamate with the Salmonella/mammalian microsome test.

Pyridinol carbamate was nitrosated to the N,N1-dinitroso derivative and the structure was proved by spectroscopic methods, including chemical ionization mass spectroscopy. By the Ames test, the dinitroso derivative showed a significant dose-dependent mutagenic response with Salmonella typhimurium strains TA 1535 and TA 100; the response became more pronounced in the presence of microsomes. As the dosage of N-nitroso pyridinol carbamate increased, the number of revertant colonies also increased. Pyridinol carbamate was not mutagenic.

[Morphogenesis of intracytoplasmic oncornaviruses]. / Intracitoplazmatikus A-típusú oncorna vírusok morfogenezise.

Intracytoplasmic oncorna viruses type-A are de novo formed in the cytoplasma, independently of the organella. In the early phase of the morphologenesis an electrondense patch-like area and the disappearence of the ribosomes can be observed. Double-membrane structures consisting of gylcoprotein can be seen in form of segments, horseshoes or rings. In the centre of the viruses ribosoma-like inclusions may be observed. Viruses of tubular structure appear to be of peculiar forms of the formation of crystals, the mechanism of which is yet unknown.

Carcinogenic effect of a quanidine pesticide administered with sodium nitrite on adult mice and on the offspring after prenatal exposure.

Adult Swiss mice were treated intragastrically during the last week of pregnancy with the fungicide dodecylquanidine acetate (dodine, DGA) together with 0.05% sodium nitrite. The incidence of malignant lymphomas, lung adenomas and hepatomas was 30--70% in females. The first tumors appeared 4 months after delivery in the FO generation and at 6--7 months in the F1 generation. Among the untreated control mice the frequency of spontaneous tumors was 6%, and lymphomas developed, if at all, only after 10 months. The oncogenic activity of DGA with sodium nitrite in the offspring was dependent on the dose of DGA.A and C type RNA virus particles were demonstrated in lymphomas by electronmicroscopy. DGA alone had no effect on the cancer incidence.

Transplacental induction of lymphomas in Swiss mice by carbendazim and sodium nitrite.

Swiss mice at different stages of pregnancy were treated intragastrically with the pesticide Carbendazim (MBC, BCM, methyl-2-benzimidazole carbamate) together with sodium nitrite. Lymphomas developed in 33.3% of young mice whose mothers were treated in the first week of pregnancy, in 53.3% of whose mothers were treated during the second week, and in 38.8% of those born of mothers treated during the third week. Treatment during the whole period of pregnancy yielded on an average 70.0% malignancy in offspring. However, administration of Carbendazim by itself did not produce lymphomas in the first generation. In lymphomas induced by in vivo-formed n-nitroso compounds, A- and C-type oncornavirus particles were observed with the electron microscope.