Non-carcinogenicity of hair dyes: lifetime percutaneous applications in mice and rabbits

6 Final Report on the Safety Assessment of p-Phenylenediamine

p-Phenylenediamine is a cosmetic hair dye intermediate used in permanent hair coloring products at concentrations of up to 5 percent (diluted 1:1 with an oxidizing agent prior to application). The extensive animal toxicity test data on p-Phenylenediamine and permanent cosmetic hair dyes containing this compound show that the degree of toxicity varies with concentration, test system and animal species. Animal data support a conclusion that this compound is neither a teratogen nor a carcinogen. Epidemiological data also support that hair dyes containing this ingredient are not carcinogenic. p-Phenylenediamine is a sensitizer and some persons may be sensitized under intended conditions of use.

For those persons not sensitized, it is concluded that p-Phenylenediamine is safe as a hair dye ingredient at the current concentrations of use.

Final Report on the Safety Assessment of Ammonium and Glyceryl Thioglycolates and Thioglycolic Acid

Ammonium and Glyceryl Thioglycolates and Thioglycolic Acid are used predominantly in cosmetic permanent waving lotions at concentrations up to 15.4% (as Thioglycolic Acid). At use concentrations, these cosmetic ingredients are only slightly toxic in acute single oral and dermal exposures. In repeated dermal tests for extended periods of exposure, these ingredients were toxic. Commercial permanent wave products produced transient conjunctival redness to both rinsed and unrinsed eyes.

The results of skin testing for irritation and sensitization of these Thioglycolates depends on the type of test system used. Under occlusive patch testing, the data indicate that these ingredients are cumulative irritants and possibly weak sensitizers, but not under semi-occlusive test conditions. In clinical patients, mainly hairdressers, Glyceryl Thioglycolate elicited allergic reactions at concentrations down to 0.25%. It is concluded that these cosmetic ingredients may be safely used at infrequent intervals. However, hairdressers should avoid skin contact.

Final Amended Report on the Safety Assessment of Ammonium Thioglycolate, Butyl Thioglycolate, Calcium Thioglycolate, Ethanolamine Thioglycolate, Ethyl Thioglycolate, Glyceryl Thioglycolate, Isooctyl Thioglycolate, Isopropyl Thioglycolate, Magnesium Thioglycolate, Methyl Thioglycolate, Potassium Thioglycolate, Sodium Thioglycolate, and Thioglycolic Acid

This safety assessment includes Ammonium and Glyceryl Thioglycolate and Thioglycolic Acid Butyl, Calcium, Ethanolamine, Ethyl, Isooctyl, Isopropyl, Magnesium, Methyl, Potassium, and Sodium Thioglycolate, as used in cosmetics. Thioglycolates penetrate skin and distribute to the kidneys, lungs, small intestine, and spleen; excretion is primarily in urine. Thioglycolates were slightly toxic in rat acute oral toxicity studies. Thioglycolates are minimal to severe ocular irritants. Thioglycolates can be skin irritants in animal and in vitro tests, and can be sensitizers. A no-observable-adverse-effect level for reproductive and developmental toxicity of 100 mg/kg per day was determined using rats. Thioglycolates were not mutagenic, and there was no evidence of carcinogenicity. Thioglycolates were skin irritants in some clinical tests. Clinically significant adverse reactions to these ingredients used in depilatories are not commonly seen, suggesting current products are formulated to be practically nonirritating under conditions of recommended use. Formulators should take steps necessary to assure that current practices are followed.

The debate on carcinogenicity of permanent hair dyes: new insights

Oxidative (permanent) hair dyes contain one or several "primary intermediates" (e.g., p-phenylenediamines, p-aminophenols) and "couplers" (e.g., m-aminophenols, m-hydroxyphenols). In the presence of peroxide, the primary intermediate(s) and the coupler(s) undergo a chemical reaction to form colored oligomers. In the 1970s a number of aromatic amines used in oxidative hair dyes were identified as mutagenic and/or carcinogenic in rodents after lifetime oral administration. In response, regulatory action was taken, and some hair dye ingredients were banned in the European Union. Although recent results suggest that the main "primary intermediate" of oxidative hair dyes, p-phenylenediamine, has a weak genotoxic potential in vitro, it was not mutagenic in a mixture with nonmutagenic couplers, if tested under conditions comparable to those of practical use. Under conditions of use of permanent hair dyes, between 0.1 and 0.5% of the applied p-phenylenediamine may be absorbed through the skin. Acetylation in the skin is a key metabolic step for the primary intermediates p-phenylenediamine and p-aminophenol. Because of the involvement of aromatic amines, the discussion on the carcinogenicity of hair dyes in humans has been focused on urothelial cancer. Numerous epidemiological studies have investigated the risk of bladder cancer associated with the profession as a hairdresser, as well as the risk to consumers of hair dyes. Although some earlier studies suggested an overrepresentation of bladder cancer in male hairdressers, the majority of modern studies do not show an increase in relevant bladder cancer risk for professional or personal use of oxidative hair dyes. Today, there seems to be no relevant bladder cancer risk from the use of oxidative hair dyes. Such a conclusion can be derived from new toxicokinetic and metabolism investigations and is in general accordance with current epidemiological data. Human urothelial cancers, chemically induced by aromatic amines, have typical latency times often longer than 20 years. Since earlier exposures could have an impact decades later, the possibility of bladder cancer in hairdressers having intensively worked with permanent hair dyes during earlier decades (prior to the 1980s) should be taken into account.

Toxicity and human health risk of hair dyes

Hair dyes and their ingredients have moderate to low acute toxicity. Human poisoning accidents are rare and have only been reported following oral ingestion. Contact sensitisation to hair dyes has been a safety issue, mainly as a consequence of unprotected professional exposure. Although the use of hair dyes has dramatically increased in industrialised countries during the last decades, the prevalence of sensitisation to hair dyes in the general and professional populations has stabilised or declined. In vitro genotoxicity tests on hair dye ingredients frequently had positive results, although their correlation with in vivo carcinogenicity for the chemical class of oxidative hair dye ingredients (aromatic amines) is uncertain. Positive in vivo genotoxicity results on hair dyes are rare. Studies in man found no evidence of genotoxic effects of hair dyes or their ingredients. On the basis of mechanistic studies, some in vivo positive hair dye ingredients (p-aminophenol, Lawsone) have been shown to pose no or negligible risk to human health. Although a recent case-control epidemiology study suggested an association of hair dye use and bladder cancer, a number of other studies, including prospective investigations on large populations, found no or negative correlations for bladder or other cancers. Although in vivo topical carcinogenicity studies on hair dye ingredients or commercial formulations yielded no evidence for systemic toxicity or carcinogenicity, oral carcinogenicity studies on hair dye ingredients at oral doses up to the maximum tolerated dose (MTD) suggested that some ingredients are carcinogenic in rodents. Human systemic exposure to various (14)C-labelled oxidative hair dyes under conditions of use was below 1.0% of the amount applied. Conservative risk assessments suggested no or negligible cancer risk, including for ingredients that were found to be positive in oral carcinogenicity studies. The results of reproductive toxicity studies and epidemiological investigations suggested that hair dyes and their ingredients pose no risk of adverse reproductive effects. In conclusion, the weight of evidence suggests that consumer or professional exposure to hair dyes poses no carcinogenic or other human health risks.

Non-carcinogenicity of 2,2'--(4-aminophenyl)imino-bisethanol sulfate in a long-term feeding study in Fischer 344 rats

2,2'-[(4-aminophenyl)imino]bisethanol sulfate (4APE) was administered at dietary levels of 0 (control), 300, 1000 and 3000 ppm to groups of 50 male and 50 female Fischer 344/DuCrj rats for 104 wk. As slight body weight retardation was observed in the male 3000 ppm group in the preliminary 13-wk feeding study, this dose was selected for the highest exposure level. Mean body weights of both sexes in the 3000 ppm group were lower than those of the controls from wk 2 to termination. However, there were no treatment-related clinical signs or adverse effects on survival rate, food consumption or haematology data. Very slight but statistically significant increases in relative thyroid weights were found in males of the 3000 ppm group, but there was no significant treatment-related increase in the incidence of any non-neoplastic or neoplastic lesions. Thus, under the experimental conditions used, 4APE was not carcinogenic in Fischer 344 rats of either sex.

An epidemiologic case-control study of breast cancer and exposure to hair dyes

An epidemiologic case-control study of 1617 patients with a primary breast cancer and 1617 control subjects was conducted to test the hypothesis that use of hair dyes is related to breast cancer. No overall association was observed between breast cancer risk and "ever use" of hair dyes (odds ratio, 1.04; 95% confidence interval, 0.90 to 1.21), age when hair dye use started and age when it stopped, duration of hair dye use (years), types of hair dyes used, and estimated lifetime number of individual applications. The current data set also failed to show an increased risk for breast cancer in women who had been diagnosed with benign breast disease and were exposed to hair dyes.

Multigeneration reproduction and carcinogenicity studies in Sprague-Dawley rats exposed topically to oxidative hair-colouring formulations containing p-phenylenediamine and other aromatic amines

Two-generation reproduction and chronic toxicity-carcinogenicity studies were conducted in Sprague-Dawley rats receiving topical applications of six oxidative hair-colouring formulations. These formulations were prepared as prototypes of permanent hair colourings using the base ingredients and primary intermediates and couplers most often used in this kind of product. Among the dyes included in the various formulations were p-phenylenediamine, p-toluenediamine, p-aminophenol, resorcinol, m-aminophenol, 1-naphthol, 2-amino-4-nitrophenol, 4-chlororesorcinol, p-aminodiphenylamine hydrochloride and N-methyl-p-aminophenol sulphate. The dye solutions were mixed with an equal volume of 6% hydrogen peroxide prior to application. In the reproduction study the samples were applied topically twice weekly throughout the growth, mating, gestation and lactation phases of the F0 parents to the weaning of the F1a and F2b litters. Fertility, gestation and foetal viability indices and body weights were evaluated for the six treatment groups and these were compared with the values for the three concurrent control groups. Weanlings selected from the F1a litters were the subjects for the lifetime carcinogenesis study. For 24 months they received twice-weekly topical applications of the same dyes as were administered to their parents. Clinical chemistry, haematological and urinalysis studies were performed at months 3, 12, 18 and 24, and five animals/sex/group were killed at month 12 and autopsied for histological examination of the rat tissues. All animals in the chronic study were evaluated for incidence of neoplastic and non-neoplastic lesions. In the reproduction phase the application of hair dyes had no adverse effect on the fertility of the males or females, or on gestation, lactation and weaning indices. The average number weaned per litter and the mean body weights of the weanlings were comparable among the treated and control groups. No treatment-related gross lesions were observed in any animals necropsied at month 12 or at study termination, or in any rats that died during the course of the carcinogenicity study. Comparison of the tumour incidences among the six treated and three control groups showed some significant variations among those tumours occurring most frequently in this strain of rats, and pituitary adenomas were also increased significantly (P less than 0.05) in the females of one of the treated groups. The incidence of this tumour is known to be high and variable in untreated female Sprague-Dawley rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Chemical carcinogens. A review and analysis of the literature of selected chemicals and the establishment of the Gene-Tox Carcinogen Data Base. A report of the U.S. Environmental Protection Agency Gene-Tox Program

The literature on 506 selected chemicals has been evaluated for evidence that these chemicals induce tumors in experimental animals and this assessment comprises the Gene-Tox Carcinogen Data Base. Three major sources of information were used to create this evaluated data base: all 185 chemicals determined by the International Agency for Research on Cancer to have Sufficient evidence of carcinogenic activity in experimental animals, 28 selected chemicals bioassayed for carcinogenic activity by the National Toxicology Program/National Cancer Institute and found to induce tumors in mice and rats, and 293 selected chemicals which had been evaluated in genetic toxicology and related bioassays as determined from previous Gene-Tox reports. The literature data on the 239 chemicals were analyzed by the Gene-Tox Carcinogenesis Panel in an organized, rational and consistent manner. Criteria were established to assess individual studies employing single chemicals and 4 categories of response were developed: Positive, Negative, Inconclusive (Equivocal) and Inconclusive. After evaluating each of the individual studies on the 293 chemicals, the Panel placed each of the 506 chemicals in an overall classification category based on the strength of the evidence indicating the presence or absence of carcinogenic effects. An 8-category decision scheme was established using a modified version of the International Agency for Research on Cancer approach. This scheme included two categories of Positive (Sufficient and Limited), two categories of Negative (Sufficient and Limited), a category of Equivocal (the evidence of carcinogenicity from well-conducted and well-reported lifetime studies had uncertain significance and was neither clearly positive nor negative), and three categories of Inadequate (the evidence of carcinogenicity was insufficient to make a decision, however, the data suggested a positive or negative indication). Of the 506 chemicals in the Gene-Tox Carcinogen Data Base, 252 were evaluated as Sufficient Positive, 99 as Limited Positive, 40 as Sufficient Negative, 21 as Limited Negative, 1 as Equivocal, 13 as Inadequate with the data suggesting a positive indication, 32 as Inadequate with the data suggesting a negative indication, and 48 Inadequate with the data not suggesting any indication of activity. This data base was analyzed and examined according to chemical class, using a 29 chemical class scheme.(ABSTRACT TRUNCATED AT 400 WORDS)

Evaluation of the toxicity and carcinogenicity of hair dyes

The chronic toxicological and carcinogenic potential following skin painting in mice was evaluated for nine oxidative and three nonoxidative hair dyes. Groups of male and female Swiss mice were treated one time weekly for at least 20 mo with one dose level of each dye. The oxidative dyes were mixed 1:1 with 6% hydrogen peroxide before treatment and the three semipermanent formulations were applied without dilution. Control groups were shaved only and received no applications. Body weights and survival rates did not differ between appropriate male and female treatment and control groups. Absolute and relative liver and kidney weights were equivalent for treatment and control groups. After 7 and 9 mo of treatment, 10 males and 10 females randomly selected from each group were necropsied and tissues taken for histopathologic evaluation. Animals found dead or sacrificed in moribund condition or at termination of the study were necropsied and evaluated histopathologically. Comparison of incidence of tumors and of nontumor pathology among the various treatment and control groups revealed no biologically significant differences. Toxicological and carcinogenic effects were not induced by the hair dye formulations.