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.

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.

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.

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.

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.

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.

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.

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.

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 aquarium fish

The effects of nine carcinogens on 1,220 guppies [Poecilea reticulata (Lebistes reticulatus)] and 40 zebra fish (Danio rerio) were studied. Multiple exposure techniques included skin application, im and ip injections, feeding, implantation in pellets, and dissolving of the compound in the aquarium water. 7-12-Dimethylbenz[a]anthracene, 3-methylcholanthrene, and benzidine produced no tumors in the fish. N-2-Fluorenylacetamide, omicron-aminoazotoluene, 4-dimethylaminoazobenzene, diethylnitrosamine, and dimethylnitrosamine induced tumors in the livers of some of the fish. These neoplasms included cholangiomas, hepatoadenomas, cholangiocarcinomas, and hepatocellular cancers. Nitrosomorpholine caused not only hepatic tumors in guppies and zebra fish but also intestinal adenocarcinomas and poorly differentiated connective-tissue lesions in the abdominal cavities of zebra fish. Experimental induction of tumors in aquarium fish offers wide possibilities for comparative cancer research. Fish are a suitable model for the testing of compounds for carcinogenic activity and for the screening of environmental carcinogens.