Non-carcinogenicity of 2,2'--(4-aminophenyl)imino-bisethanol sulfate in a long-term feeding study in Fischer 344 rats

2,2'-[(4-aminophenyl)imino]bisethanol sulfate (4APE) was administered at dietary levels of 0 (control), 300, 1000 and 3000 ppm to groups of 50 male and 50 female Fischer 344/DuCrj rats for 104 wk. As slight body weight retardation was observed in the male 3000 ppm group in the preliminary 13-wk feeding study, this dose was selected for the highest exposure level. Mean body weights of both sexes in the 3000 ppm group were lower than those of the controls from wk 2 to termination. However, there were no treatment-related clinical signs or adverse effects on survival rate, food consumption or haematology data. Very slight but statistically significant increases in relative thyroid weights were found in males of the 3000 ppm group, but there was no significant treatment-related increase in the incidence of any non-neoplastic or neoplastic lesions. Thus, under the experimental conditions used, 4APE was not carcinogenic in Fischer 344 rats of either sex.