Carcinogenicity studies, rodent neoplasms

Scales MDC, Andrews Z. The use of two compatible rodent strains to improve the sensitivity of carcinogenicity studies a data review of spontaneous rodent neoplasms. Adv Drug React Toxicol Rev 1991 10 99-111. 

Decreased incidences were found in some neoplasms. These included fibroma and fibroadenoma of the mammary gland in female Sprague-Dawley rats treated with MTBE pancreatic islet adenoma or carcinoma in male rats treated with TBA Harderian gland adenoma and carcinoma in male mice and hepatocellular adenomas and adenomas and carcinomas combined in male mice also treated with TBA. These findings received no supporting evidence from other studies and are therefore considered to be chance findings. It is considered that the variations observed are typical of those that occur in rodent carcinogenicity studies and no interpretation of a beneficial effect of exposure to TBA is intended. 

Chronic inhalation exposure of rodents to 1,2-dibromoethane has been associated with neoplasms in the respiratory tract, as well as in other organ systems. Two studies have examined the carcinogenic potential of 1,2-dibromoethane in rodents after inhalation exposure (NTP 1982 Wong et al. 1982). There was also an A strain mouse assay (Adkins et al. 1986). 

Two-year inhalation studies (6 hours/day, 5 days/week for 103 weeks) in rodents showed clear evidence of carcinogenicity. Mice exposed at 375 and 750ppm had increased incidences of harderian gland adenomas and carcinomas female mice exposed at 188 and 750 ppm had increased liver neoplasms female rats in the 188 and 375ppm-exposed groups had increased incidences of mammary gland fibroadenomas and carcinomas. Other treatment-related effects were an increase in nasal lesions and degeneration of the respiratory epithelium in mice. 

A number of early studies also demonstrated the carcinogenicity of VCD in rodents. Dermal application of 16 mg, 5 days per week, for 12 months resulted in squamous cell carcinomas or sarcomas in 9 of 20 exposed male mice. One skin neoplasm and four malignant lymphomas occurred in 16 of 20 mice surviving a total dermal dose of 70 mg over 14 months. ... 

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