Final report on the safety assessment of Basic Blue 99

Basic Blue 99 is a direct, nonoxidative hair colorant used in temporary and semipermanent hair dyes. According to current reported usage data, Basic Blue 99 is used at concentrations from 0.004% to 2% and the most often reported use is in hair tints. Hair dyes containing Basic Blue 99, as "coal tar" hair dye products, are exempt from the principal adulteration provision and from the color additive provision of the Federal Food, Drug, and Cosmetic Act of 1938 when the label bears a caution statement and "patch test" instructions for determining whether the product causes skin irritation. Preliminary testing on or by individuals should be done using an open patch test that is evaluated at 48 h after application of the test material. Users, therefore, would be able to determine their individual reactions to hair dye products containing Basic Blue 99. Basic Blue 99 dye is approximately 60% to 63% dye, whereas the remainder of the mixture is composed of sugar (similar to 25.7%), volatile matter/water crystallization (similar to 1.8%), and inorganic salts (bringing the mixture to 100%). The dermal absorption of Basic Blue 99 is low in both rats and humans. The LD50 values of Basic Blue 99 in mice and rats were 2.7 g/kg and between 1.0 g/kg and greater than 2.0 g/kg, respectively. Mice and rats orally administered Basic Blue 99 for 90 days did not show any indications of cumulative toxicity. Discoloration of organs involved in the elimination of Basic Blue 99 from the animals was noted in both test species. In rabbits, Basic Blue 99 did not cause ocular irritation, but some discoloration was noted. Basic Blue 99 caused minimal dermal irritation in rabbits. Sensitization occurred in animals exposed to Basic Blue 99 in a DMSO vehicle, but not in a water vehicle in guinea pigs and mice. Basic Blue 99 administered by gavage did not cause developmental toxicity in rats. Basic Blue 99 was a weak mutagen with and without metabolic activation in the Ames test, producing both reverse and frameshift mutations, but did not induce mutations in Escherichia coli or in any mammalian cells tested. In a modified repeated-insult patch test (RIPT), no volunteers had any reaction to Basic Blue 99 after a 1-h occlusive challenge. Case reports have documented positive patch test results to 1% Basic Blue 99 in three patients. A current review of the hair dye epidemiology literature identified that use of direct hair dyes, although not the focus in all investigations, appears to have little evidence of an association with cancer or other adverse events. The Panel recognizes that hair dye epidemiology studies do not address the safety of individual hair dyes. Based on the available safety test data on Basic Blue 99, however, the Panel determined that this ingredient would not likely have carcinogenic potential as used in hair dyes. The Cosmetic Ingredient Review Expert Panel concluded that Basic Blue 99 is safe as a hair dye ingredient in the practice of use and concentration as described in this safety assessment.