Testing Hair Dyes

In addition to cream and gel formulations, powder hair dyes are also marketed, but to a lesser extent. Besides the dye intermediates, they contain thickeners and oxidants in powder form. They are stirred with water before use. 

Metal salt dyes cannot be removed with these preparations because of the catalytic decomposition of hydrogen peroxide and their resistance to reducing agents. 

Direct dye tints can be removed by washing with shampoo (the rate of removal depending on the type of dye) or, in some cases, by rubbing the hair with ethanol. 

Hair dyes must meet a number of conditions related to their end use. Color can be assessed by colorimetry [49], The limits of precision are set by the substrate on which the measurement is performed. Studies on test subjects are difficult because of the uneven natural hair color and the background color of the scalp. Tresses are hard to prepare at a constant quality level. Measurements on wool cloth give reproducible results, but for oxidation dyes the shades are not identical to those produced on hair. Colorimetric methods are therefore useful only for comparative measurements on the same object, for example, in lightfastness tests. Because hair must be redyed after four to six weeks due to growth, the fastness required of hair dyes is generally less than that needed for textiles. However, stability is still a problem with many indo dyes (see Section 5.4.3). Some of them 

The history of cosmetology, past experience with the safety of cosmetic products, and in particular statistics published by poisoning advisory centers show that the cosmetic industry in general has met these criteria [55], This is achieved by continuously evolving safety assessment strategies which take into account the actual state of the art in safety and toxicity testing. 

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The dibydrochloride salt is used as a photographic developer. It also is employed as an intermediate in the manufacture of fur dyes, in hair dyeing, as a reagent in testing for ammonia and formaldehyde, and as an oxygen scavenger in water to prevent boiler corrosion (173). 

Hair colorants, the fourth class of color additives, may be used only to color scalp hair and may not be used in the area of the eye. Use of these colorants is exempt, that is, coal-tar hair dyes may be sold with cautionary labeling, directions for preliminary (patch) testing, and restrictions against use in or near the eye. The EDA diligently enforces the rules governing color additives and limits the use of, or even dehsts colorants deemed unsafe. The Hst of substances specifically prohibited for use in cosmetics is short. 

RECOVERY OF TESTED COMPOUNDS IN OXIDATIVE HAIR DYES... 

Among the chemicals which have been shown to be mutagens in Salmonella (as well as other short-term tests) that have recently been shown to be carcinogens are 1,2-dichloroethane (10 x 109 Ibs/year, U.S.), tris-dibromopropyl phosphate (the flame retardant used in children s polyester sleepwear), sulfallate (a pesticide), o-phenylene-diamine, 2,4-diaminoanisole (hair dye ingredient), 2-nitro-p-phenylenediamine (hair dye ingredient), and 4-amino-2-nitro-phenol (hair dye ingredient). 

So what should we make of all this The upshot of all this analysis would appear to be that modern hair dyes present no risk of causing cancer either among those who apply them or those on whose hair they are applied. If you are still not convinced that synthetic chemical dyes are safe, and yet you want to change the colour of your hair or hide any grey then you must perforce turn to the dyes of old - see box - but even some of these should come with test patches and a warning. 

C. M. Burnett and J. F. Corbett, Food Chem. Toxicol., 25,703 (1987). Failure of Short-Term in Vitro Mutagenicity Tests to Predict the Animal Carcinogenicity of Hair Dyes. 

Hair dyes (for example henna, paraphenylenediamine, and paratoluenediamine) have been reviewed (1). They have moderate to low acute toxicity. Poisoning is rare and occurs only after oral ingestion. Contact sensitization usually occurs from unprotected professional exposure, but the prevalence has stabilized or fallen over the years. In vitro genotoxicity tests of hair dye ingredients have often been positive, but the relation to in vivo... 

Contact allergy to the paraphenylene group of hair dyes is well estabhshed (2). To test for cross-reactivity between these oxidative dyes and the new generation of hair dyes, 40 hairdressers allergic to paraphenylenediamine were selected none reacted to any of the four acid dyes, two FD C dyes, or four D C dyes, suggesting that these newer hair dyes are safe alternatives to the para-phenylene-based hair dyes (3). 

A 45-year-old woman developed extensive urticarial lesions 30 minutes after the application of a hair dye, starting on the scalp and face, followed by abdominal cramps, watery diarrhea, vomiting, dysphonia, and loss of consciousness. A prick test with a 1/128 dilution of the hair dye showed a positive reaction, but individual dye constituents did not. Prick testing with the oxidation products of the individual dye constituents showed a strongly positive reaction to oxidized paratoluenediamine, which was weaker after addition of an antioxidant to the mixture. 

In rats, teratogenicity was studied by testing four commercially available hair dye formulations containing 1, 2, 3 and 4% PPD and several aromatic amine derivatives among their constituents [18]. No abnormal foetal effects were noted, except with the formulation containing 2% PPD, which induced skeletal deformities [18]. 

Of all the short-term assays, the Ames Salmonella test is clearly the best validated and most widely used and will continue to be so for a number of years to come. The assay has an excellent record for identifying organic carcinogens, particularly carcinogens which are in the aromatic amine and polycyclic hydrocarbon classes. " In addition, positive results in the Ames assay and several other short-term mutagenesis assays, have been predictive of carcinogenic activity in rodent assays for a number of compounds with widespread human exposure. Examples of these include the food preservative furylfuramide AF-2 which was used extensively in Japan from 1965 to about 1977 the flame-retardant tris-B-P (tris[2,3-dibromopropyl]phosphate) which was used to treat children s sleepwear from 1972 to 1977 and aromatic amine components of hair dye preparations. 

There are three basic steps to the usage instructions for semipermanent hair dyes first, the allergy test second, the strand test (both are described under... 

Both Corbett [5] and Kirkland [60] have summarized the results of several common hair dye ingredients in in vitro mutation tests, in dominant lethal animal testing, and in epidemiological studies. One of these testing programs consists of a Cosmetics, Toiletries and Fragrance Association (CTFA) study involving more than 35 oxidation dye components and 34 textile dyes used in temporary hair color products. From this work and other studies, the FDA has determined (in October 1979) that all hair dye prod-... 

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