Carcinogenic potential of cooked food mutagens (IQ and MeIQ) in Wistar rats after short-term exposure

Two potent cooked food mutagens, 2-amino-3-methylimidazo/4,5-f/quinoline (IQ) and 2-amino-3,4-dimethylimidazo/4,5-f/quinoline (MeIQ), were examined in an initiation-promotion assay in the male wistar rat. Fourteen doses of 10 mg IQ or 10 mg MeIQ/kg b.wt. were given during initiation, followed by promotion with 500 p.p.m. phenobarbital sodium (PB) in the drinking water up to week 58. A small number of tumours of Zymbal's gland were seen in all groups treated with IQ or MeIQ, irrespective of PB-treatment. Though the promotional regimen failed to produce the expected number of liver tumours, it did induce a significant amount of gamma-glutamyltranspeptidase (GGT) activity. These results suggest that even short exposures to low doses of IQ or MeIQ produce persistent procarcinogenic lesions in the rat, and that secondary factors, e.g. promoters or high cell turnover, may over time develop these lesions into cancer.