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2242368 
Technical Report 
Health effects of selected chemicals. Vol 4-5. 9H-Carbazole (1996) 
Anonymous 
1999 
RISKLINE/2000040012 
15 
1999 
eng 
is a chapter of 3160596 Health effects of selected chemicals
The toxicological documentation for acute toxicity of carbazole is not comprehensive. The oral LD50 in mice was reported to be more than 400 mg/kg body weight. The LDLO in rats ranged from 500 to 5000 mg/kg body weight. There is no information on symptoms, or any indications of the possible cause of death. These data do not lead to a classification. A 5% solution of carbazole in olive oil caused only very slight irritation when applied several times to rabbit skin. Carbazole has been tested for carcinogenic effects in four studies. Although some of the studies are not entirely in accordance with guidelines on carcinogenicity studies, the results of the animal experiments are "clear". In a 96-week study B6C3F1 mice were fed with diet containing 0.15% to 0.6% carbazole 192 to 863 mg/kg bw. Statistically significant increased incidences of neoplastic lesions were found in liver and forestomach of all treated animals. Carbazole caused hepatocellular carcinomas and neoplastic nodules in the liver. Furthermore, squamous cell carcinomas of the forestomach were significantly increased as well as the incidence of papillomas was higher after treatment with carbazole.
In three studies carbazole was adminstered to rats and hamsters subsequent to a dose of a nitrosamine. These studies showed that carbazole also promoted urinary bladder carcinogenesis and kidney tumours. Furthermore, an increase in number and size of hepatocellular foci and hyperplastic and papillomatous lesions in the forestomach was shown in hamsters independently of prior treatment with nitrosamine. These data lead to classification as a carcinogen, category 3, R40. The available data (references 1- 19) lead to the conclusion that carbazole seems to be slightly to moderately acute toxic to mice and rats, although the documentation is very scarce. Carbazole is carcinogenic to mice by oral administration.