Oxyquinoline is a heterocyclic
phenol and
Oxyquinoline Sulfate is its
salt, both of which are described as cosmetic
biocides for use in cosmetic formulations. In an earlier Cosmetic Ingredient Review (CIR) safety assessment, the available data were found insufficient to support safety. Currently, some uses are reported to the Food and Drug Administration (FDA) by industry, but industry reports to CIR indicate no use. In Europe,
Oxyquinoline and
Oxyquinoline Sulfate are accepted for use as stabilizers for
hydrogen peroxide in rinse-off and leave-on hair care preparations, with concentration limitations.
Oxyquinoline is metabolized and excreted in the urine as
glucuronides.
Oxyquinoline and
Oxyquinoline Sulfate exhibit little acute or subchronic toxicity in animal studies. A 100-mg dose of
Oxyquinoline was only slightly irritating to the eye.
Oxyquinoline and
Oxyquinoline Sulfate were genotoxic in certain Salmonella typhimirium strains with metabolic activation and in a mouse
lymphoma assay. There was some evidence of increased
chromosome aberrations in an in vitro study, and an increase in sister-chromatid exchanges (but not
chromosome aberrations) in rats treated with
Oxyquinoline, but no genotoxicity was found in a Drosophilia sex-linked recessive lethal test, mouse bone marrow micronucleus test, a rat bone marrow and hepatocyte micronucleus test, and unscheduled
DNA synthesis in rat hepatocytes.
Oxyquinoline did bind to
DNA in the presence of liver
enzymes. Although the International Agency for Research on
Cancer concluded that the existing evidence is inadequate to determine carcinogenicity in animals,
Oxyquinoline was noncarcinogenic in several rodent feeding studies, and newly available studies using genetically altered mice, in one case carrying the human c-Ha-ras gene, demonstrated that
Oxyquinoline was not carcinogenic. In clinical tests,
Oxyquinoline is neither an
irritant nor a sensitizer when tested at 1% in
petrolatum. The available data demonstrate that
Oxyquinoline and
Oxyquinoline Sulfate are safe as stabilizers for
hydrogen peroxide in rinse-off hair care cosmetic products in the present practices of use. For leave-on cosmetic products, however, the absence of impurities and ultraviolet (UV) absorption data resulted in a finding that the available data are insufficient to support safety. The data needed in order to complete the safety assessment of
Oxyquinoline and
Oxyquinoline Sulfate in leave-on cosmetic products are (1) UV absorption data -- if significant absorption occurs, then photoirritation/
photosensitization data will be needed; and (2) data on impurities.