The NTP has published two final reports, on the long-term toxicology, genotoxicity and carcinogenicity of indole‑3‑carbinol, and on the subchronic toxicity of tetrabromobisphenol A-bis(2,3-dibromopropyl ether) (TBBPA‑DBPE).

Rats and mice received indole-3-carbinol by oral gavage at respective doses of up to 300 and 250 mg/kg bw/day on 5 days per week for 2 years. There was “no evidence of carcinogenic activity” in male rats or female mice. “Some evidence of carcinogenic activity” was reported in female rats, based on increased incidences of malignant uterine tumours. There was “clear evidence of carcinogenic activity” in male mice, with increased incidences of liver tumours reported. A range of non-neoplastic lesions were observed in these animals. No convincing evidence of genotoxicity was reported.

The flame retardant TBBPA-DBPE was administered to rats and mice for 3 months (5 days/week) at gavage doses of up to 1000 and 2000 mg/kg bw/day, respectively. There were no treatment-related clinical findings, or effects on survival, body or organ weights, haematological or clinical chemistry parameters, or incidence of lesions. No genotoxicity was seen.

US National Toxicology Program (2017). Technical report on the toxicology studies of indole-3-carbinol in F344/N rats and B6C3F1/N mice and toxicology and carcinogenesis studies of indole-3-carbinol in Harlan Sprague Dawley rats and B6C3F1/N mice (gavage studies). NTP TR 584. July 2017.

Technical Report on the toxicity studies of tetrabromobisphenol A-bis(2,3-dibromopropyl ether) administered by gavage to F344/NTac rats and B6C3F1/N mice. NTP TOX-85. August 2017.


The above items were taken from the October 2017 issue of Toxicology and Regulatory News which is sent automatically to members of bibra.

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