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

(Group 3)

For definition of Groups, see Preamble Evaluation.

VOL.: 79 (2001) (p. 607)

CAS No.: 123712-78-7
Chem. Abstr. Name: 5-Hydroxy-2(hydroxymethyl)-4H-pyran-4-one

5.  Summary of Data Reported and Evaluation

5.1 Exposure data

Kojic acid is a natural product, which is used as a food additive and preservative, in cosmetics as a skin-whitening agent, as a plant growth regulator and as a chemical intermediate.

5.2 Human carcinogenicity data

No data were available to the Working Group.

5.3 Animal carcinogenicity data

Kojic acid was tested by oral administration in one study in mice. It produced thyroid follicular-cell adenomas in both males and females. In two initiation–promotion studies in rats, kojic acid promoted thyroid follicular-cell carcinogenesis initiated by N-nitrosobis(2-hydroxypropyl)amine.

5.4 Other relevant data

No data were available on the absorption, distribution, metabolism or excretion of kojic acid.

Kojic acid is a potent goitrogen in rodents, in which treatment results in decreased serum thyroid hormone concentrations, increased thyroid-stimulating hormone secretion, increased thyroid gland weights and diffuse follicular-cell hypertrophy and/or hyperplasia.

Kojic acid inhibited iodine uptake by the thyroid and inhibited iodine organification at high doses.

No data were available on the genetic and related effects of kojic acid in humans. Kojic acid did not induce dominant lethal mutations in mice. In the presence and absence of metabolic activation, it induced sister chromatid exchange and chromosomal aberrations, but not mutations, in hamster cells in culture. Kojic acid was mutagenic in bacteria in the presence and absence of metabolic activation. The overall data indicate that kojic acid is genotoxic in vitro.

5.5 Evaluation

There is inadequate evidence in humans for the carcinogenicity of kojic acid.

There is limited evidence in experimental animals for the carcinogenicity of kojic acid.

Overall evaluation

Kojic acid is not classifiable as to its carcinogenicity to humans (Group 3).

For definition of the italicized terms, see Preamble Evaluation.


Last updated: 25 September 2001

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       Toxicological Abbreviations