Genotoxicity and carcinogenicity testing of 1,2-dibromopropane and 1,1,3-tribromopropane in comparison to 1,2-dibromo-3-chloropropane.

The activities of 1,2-dibromopropane (DBP) and 1,1,3-tribromopropane (TBP) were studied in seven genotoxicity assays, (i) SOS-induction in E. coli, (ii) DNA repair in primary rat hepatocyte culture, (iii) the Salmonella/microsome assay, (iv) a host-mediated assay using Salmonella, (v) the somatic mutation and recombination assay in Drosophila melanogaster, (vi) HGPRT-mutagenesis assay in ARL 18 cells, and (vii) micronucleus formation assay in mouse polychromatophylic erythrocytes (PCE), forestomach (FS), glandular stomach (GS), duodenum (D), jejunum (J), cecum (C) and liver (L). The halopropanes were also tested for tumor formation in the fish Danio rerio. DBP was active in assays (ii), (v), (vii FS) and (vii L). TBP was positive in assays (ii) and (iii), strongly positive in (vii L) and borderline positive in (iv). However, neither DBP nor TBP induced tumors in fish, in contrast to the carcinogenic 1,2-dibromo-3-chloropropane. The genotoxicity and potential carcinogenicity of DBP and TBP in mammals is discussed.

Induction of hepatocellular carcinomas in the Egyptian toad Bufo regularis by an antifungal drug (griseofulvin).

Neoplastic lesions (hepatocellular carcinomas) were induced in the liver in 18 of 100 experimental toads (Bufo regularis) force fed with the antifungal drug griseofulvin, at a dose level of 0.4 mg/50 g every day. Maximal time of exposure and observation was 12 weeks. The first tumors appeared in 2 male toads 4 weeks after the initiation of feeding.

The carcinogenicity of some antimalarial drugs using the Egyptian toad Bufo regularis as a biological test animal.

Feeding Egyptian toads (Bufo regularis) with chloroquine and primaquine separately induced tumor formation in 14% and 19% of the animals, respectively. When chloroquine and primaquine were given in combination, the tumor incidence increased to 23.5%. Chloroquine feeding resulted in tumors located in the liver (lymphosarcomas) and primaquine in tumors in the kidney (histiocytic sarcomas). Toads fed chloroquine plus primaquine developed tumors in the liver, kidney, lung, and urinary bladder, and all the tumors were diagnosed as histiocytic sarcomas. It is speculated that one or more metabolites of chloroquine and primaquine (e.g., quinone) may be responsible for tumor induction in the toads.

Induction of neoplasms in Egyptian toads Bufo regularis by oil of chenopodium.

Feeding the Egyptian toad Bufo regularis with oil of the chenopodium plant induced hepatocellular carcinomas in 23% of the animals, and metastases of the primary liver tumors appeared in the kidneys of 6 toads. The earliest evidence of tumors appeared after 3 months of treatment. The average latent period of tumor induction was 3.6 +/- 0.4 months. It is speculated that oil of chenopodium may be one of the constituents of Chenopodium ambrosoides which is responsible for tumor induction in the toads B. regularis.

Flour infested with Tribolium castaneum, biscuits made of this flour, and 1,4-benzoquinone induce neoplastic lesions in Swiss albino mice.

The carcinogenic effect of flour infested with beetles (Tribolium castaneum), biscuits made of this flour, and 1,4-benzoquinone (a quinoid secretion of this beetle) was investigated using Swiss albino mice. Force feeding flour infested with T. castaneum induced liver and spleen tumors (lympholeukemia) in 35.2% of the animals. The tumor incidence was 29% in mice force fed biscuits made of infested flour, and the tumors were located in the liver (lympholeukemia) and breast (adenocarcinoma type A). In animals fed 1,4-benzoquinone, the tumor incidence was 33.6%, and the tumors were located in the liver and spleen (lympholeukemia). It is speculated that 1,4-benzoquinone, alone or in combination with other quinoid secretions of the beetles present in the flour, may be responsible for tumor induction in the organs of mice.

Adriamycin-induced neoplastic lesions in the Egyptian toad Bufo regularis.

Injecting adult toads (Bufo regularis) subcutaneously in the dorsal lymph sac with adriamycin at a dose of 2 mg/kg body weight, once every 3 weeks for 20 weeks, induced hepatocellular carcinomas in 20 out of 100 animals. Metastases of the primary liver tumors appeared in the kidneys of 7 toads.

Carcinogenic effect of force-feeding an extract of black pepper (Piper nigrum) in Egyptian toads (Bufo regularis).

50 male and 50 female Bufo regularis were treated, by force-feeding, with an extract of black pepper, at a dose level of 2 mg, 3 times a week for 5 months. The first tumors appeared after 2 months. Liver tumors (hepatocellular carcinomas, lymphosarcomas and fibrosarcomas) were found in 12 males and 18 females. Metastatic deposits of hepatocellular carcinomas were registered in the spleen, kidney, fat body and ovary.

The study of mutagenic activity of carcinogens and other chemical agents with Salmonella typhimurium assays: testing of 126 compounds.

126 chemical compounds were tested in the Ames assay with bacterial Salmonella typhimurium of 8 various strains (mainly TA 98 & TA100). For metabolic activation liver S9 from arochlortreated rats was used. In the first group of substances tested (51 compounds with confirmed carcinogenicity for animals) 45 agents possessed mutagenicity and 6 gave false-negative response (1.2-dimethylhydrazine, urethane, DDT, chloroform, carbon tetrachloride, 1.4-dioxane). In group 2 (27 compounds which did not possess carcinogenic activity) 22 agents were correctly identified and the rest 5 gave false-positive response (acrolein, styrene-oxide, acridine-orange, 1-naphtylamine, dichlormethane). After summation of data obtained test sensitivity for both groups together made 88.2%, specificity--81.5%, and predictive value--90%. In group 3 (48 compounds, presented by chemical, pharmaceutical and food industries, in respect of which either there are insufficient data on their carcinogenicity, or they were tested for the first time), 8 appeared mutagenic (1-aminoanthraquinone, 2-aminoanthraquinone, 1-amino-4-chloranthraquinone, 2-amino-3-oxyanthraquinone, Rhodulin blau 5B, dinitrochlorbenzene, nitrosodiphenylamine and 2,3,5-trinitronaphthalene).

Chemical carcinogens and chemical carcinogenesis--a glossary.

A glossary of terms related to chemical carcinogenesis is presented. The definitions proposed are based on the current state of understanding mechanisms of the action of chemical carcinogens.

Use of aquarium fish, Danio rerio and Poecilia reticulata, as test species for evaluation of nitrosamine carcinogenicity.

The carcinogenic effects of various doses of dimethylnitrosamine (DMNA), diethylnitrosamine (DENA), and nitrosomorpholine (NM), as well as the results of varying temperature and length of exposure to these carcinogens, were studied in short-term (20-21 wk) experiments in aquarium fish (820 Danio rerio and 944 Poecilia reticulata). All nitroso compounds induced liver tumors (hepatocellular carcinomas and adenomas, cholangiomas, and cholangiocarcinomas) and esophageal papillomas. Exposure to NM also induced intestinal adenocarcinomas in D. rerio. At a conventional temperature (22 degrees +/- 1 degree C), tumors were induced in 76% of the D. rerio in an average of 13.8 weeks following an initial 8-week exposure to 100 ppm DMNA and in 22% of P. reticulata in an average of 10.9 weeks. The DENA exposure resulted in tumors in 61.5% of Danio by 15 weeks and in 29% of Poecilia in 15.5 weeks. Under the same conditions, 500 ppm NM induced tumors in 78% of the zebra fish in 15.6 weeks and in 75% of the guppies after 12.3 weeks. When exposure time was shortened to 2 weeks, the dosage was decreased, or if the temperature was reduced to 17 degrees +/- 1 degree C, the tumor incidence dropped and the latency increased. An increase in temperature to 27 degrees +/- 1 degree C resulted in a 72-89% tumor incidence and shortened the latency to 11.3-14.1 weeks. Thus the modulation of our experimental conditions to maximize tumor incidence and minimize mean latency permitted the use of the aquarium fish D. rerio and P. reticulata for the screening of carcinogenic nitrosamines.

Dysplastic lesions and abnormalities in amphibians associated with environmental conditions.

High incidence of developmental anomaly and tumor-like dysplasia of osteochondrous tissue of hind limbs has been detected in frogs and toads the larval development of which has taken place in water, contaminated with sewage. Correlation between frequency of dysplasia and the level of water oxidation has been noted. Study on histogenesis of the marked tumor-like dysplasia were performed. It is assumed that the major mechanism responsible for anomaly consists in cytotoxic effect of teratogenic agent and that the differentiation lesion of cartilaginous tissue is caused by blocking of maturation and death of chondrocytes.

Peculiarities of N-nitramines carcinogenic action.

Carcinogenic action of dimethylnitramine (DMNO), diethylnitramine (DENO), and dibuthylnitramine (DBNO) on various animal species was studied. 200 ppm of DMNO in tap water induced no tumours in outbred rats, while DBNO induced hyperplastic lesions on the urinary bladder and DENO produced liver tumours in 2 of 5 rats. DMNO dissolve in aquarium water at a dose of 5 ppm induced tumours (kidney and liver adenocarcinomas and hemocytoblastosis) in 18 out of 40 and 6 out of 18 frogs respectively. Another amphibian species, Xenopus, showed similar sensitivity to DMNO action: hepatocellular cancers, cholangiocarcinomas and kidney tumours were found in 6 out of 14 animals and in another group, in 6 out of 17 animals treated with 400 ppm of DMNO dissolved in aquarium water. Few neoplasms were observed in experiments on fish (guppies zebrafish) and freshwater mollusks treated with DMNO and DENO. The carcinogenic effect of nitramines, appears to be much lower than that of related nitrosamines.

Liver and kidney tumors induced by N-nitroso-dimethylamine in Xenopus borealis (Parker).

N-nitroso-dimethylanine dissolved in aquarium water at a concentration of 400 ppm (1/4 of the LD50/30d) induced malignant tumors in 39 (54.2%) out of 72 young adult animals of the amphibian species Xenopus borealis. The first tumor was detected at 11 weeks, and the average latency was 35.1 weeks. Tumors were located in the liver (32 cholangiocarcinomas and 13 hepatocellular cancers) and the kidney (9 adenocarcinomas and 2 anaplastic cancers). Thirteen animals bore two or more types of tumors. These results demonstrate that a high percentage of tumors can be induced in amphibians by chemical carcinogens if appropriate methods are used.

On spontaneous skin tumours in amphibia.

In 7 from 320 Rana temporaria grass frogs and 16 from 978 Rana ridibunda pond frogs, the 31 and 47 spontaneous skin tumors respectively, were observed. The tumors were represented by cystadenopapillomas and adenocarcinomas, and developed from epithelium of skin mucous glands. The spontaneous pigment tumors (melanophoromas) were found in 2 axolotls Ambistoma mexicanum. These tumors developed from hyperplastic melanophores in pigment spots and focal proliferations of melanophores located deeply in derma.

Multiple melanomas in the axolotl Ambystoma mexicanum.

Multiple melanophoromas in the axolotl Ambystoma mexicanum were characterized by cell anaplasia and polymorphism. Pigment spots may be the first stage of tumor development.

Tumor induction by N-nitroso compounds in bivalve mollusks Unio pictorum.

Diethylnitrosamine (DENA) and dimethylnitrosamine (DMNA) dissolved in tank water induced neoplasms in bivalve mollusks Unio pictorum. DENA induced tumors in 18% of the animals exposed to 200 ppm and 68% of those exposed to 400 ppm; average latent periods were 71 and 61 days, respectively. DMNA induced tumors in 8% of the animals exposed to 200 ppm for 51 days and 27% of those exposed for 152 days with average latent periods of 85 and 81 days, respectively. Neoplasms were observed in the digestive gland (basophilic cell tumors; 38 cases), the hemopoietic system (hemocytoblastosis; 12 cases) and the kidney (poorly differentiated carcinoma; 1 case). It is expedient to use mollusks, both for testing of N-nitroso compounds and as a biologic indicator of hydrospheric pollution.

Tumor induction by carcinogenic agents in anuran amphibian Rana temporaria.

Effects of 12 chemical cancerogenic agents have been studied in 910 anuran amphibia of the grass frog Rana temporaria. Tumors developed by administration of 8 of the agents studied. Dimethyl, diethyl and dibutylnitrosamines dissolved in water induced tumors in 44.2, 43.6 and 50% of animals, respectively; benzidine and 2-acetylaminofluorene administered subcutaneously and per os--in 46.6 and 41.2%, respectively, whereas p-dimethylaminoazobenzene and orthoaminoazotoluene (per os and subcutaneously)-in 30--33.3% of cases. Diethylstilbestrol-propionate induced tumors in 21% of cases. All the tumors developed within relatively short periods of time (15.6--31.9 weeks) and were located in the liver (hepatocellular cancer, hepatoadenomas) and the haemopoetic system (hemocytoblastosis). In control group of animals 3 amphibia developed multiple tumors of skin-cystadenopapillomas. The results obtained testify to the common mechanism of cancerogenesis in classes of vertebrates. In addition, the findings presented indicate to the suitability of amphibia as a new experimental object in oncology as well as to the applicability of these animals for purposes of express diagnostics of cancerogenicity. It may successfully serve as a biological indicator of environmental pollution with blastomogenic agents.

The induction of tumors in Rana temporaria with nitrosamines.

Dimethylnitrosamine (DMNA) and diethylnitrosamine (DENA) dissolved in tank water in a dose of 5 and 50 ppm, resp. induced tumors of liver (hepatocellular cancers and adenomas), and of hematopoietic system (hemocytoblastosis). DMNA induced neoplasms in 19 of 43 frogs (44.2%); the average latent period being 18.2 weeks, while DENA induced tumors in 41 of 94 animals (43.6%) within a mean latent period 19.7 weeks. Results of this investigation show the possibility to use anuran amphibians in shorttermed experiments in the study of nitrosocompounds carcinogenicity as well as a biological indicator for environmental pollution.