International Agency for Research on Cancer (IARC) - Summaries & Evaluations

(Group 2B)

For definition of Groups, see Preamble Evaluation.

VOL.: 56 (1993) (p. 197)
CAS No.: 77094-11-2
Chem. Abstr. Name: 3,4-Dimethyl-3H-imidazo[4,5-f]quinolin-2-amine

5. Summary of Data Reported and Evaluation

5.1 Exposure data

MeIQ (2-Amino-3,4-dimethylimidazo[4,5-f]quinoline) has been found in cooked meat and fish. A few determinations indicated that the levels of MeIQ were lower than those of IQ, MeIQx and PhIP.

5.2 Human carcinogenicity data

No data directly relevant to an evaluation of the carcinogenicity to humans of MeIQ were available. Studies on the consumption of cooked meat and fish are summarized in the monograph on IQ.

5.3 Animal carcinogenicity data

MeIQ was tested for carcinogenicity by dietary administration in one study in mice and in one study in rats. In mice, hepatocellular adenomas and carcinomas were induced in females and papillomas and squamous-cell carcinomas of the forestomach in animals of each sex in a dose-dependent manner. In rats, oral administration of MeIQ produced squamous-cell carcinomas of the Zymbal gland and oral cavity and adenomas and adenocarcinomas of the colon in animals of each sex, squamous-cell carcinomas of the skin in male rats and mammary adenocarcinomas in female rats.

Sequential administration of MeIQ after N-nitrosodiethylamine enhanced the appearance of foci of altered hepatocytes in rat liver.

5.4 Other relevant data

No data were available on the genetic and related effects of MeIQ in humans.

MeIQ bound to DNA and induced DNA damage and sister chromatid exchange in rodents treated in vivo. It induced DNA damage and gene mutation in rodent cells in vitro and gene mutation in insects. It induced DNA damage and mutation in bacteria.

MeIQ can be metabolized by human liver microsomes to a species that damages bacterial DNA.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of MeIQ.

There is sufficient evidence in experimental animals for the carcinogenicity of MeIQ.

Overall evaluation

MeIQ (2-Amino-3,4-dimethylimidazo[4,5-f]quinoline) is possibly carcinogenic to humans (Group 2B).

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Suppl. 7 (1987) (p. 65)

Last updated 08/21/1997

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       Toxicological Abbreviations