Percutaneous absorption and elimination of an aromatic hair dye

Hair dyes: a systematic review of pertinent in vivo human studies

What is the safety of hair dyes in human use? To address this, the penetration of hair dyes into human bodies must be quantified. This article provides a critical overview to update work published in the area of in vivo hair dye penetration in humans. Studies are in humans, with one including rhesus monkey and one including in vitro human skin. MEDLINE, PubMed, Embase, Scopus, Web of Science, and Google Scholar databases were searched from 2004 to October 2019 for articles with experimental methodology on in vivo percutaneous absorption of hair dyes in humans and six studies were included. Findings indicate that percutaneous penetration occurs with hair dye use, with less absorbed in hairdressers. However, much remains unknown about the penetration of the over 200 commercially available hair dyes. A major void exists in data confirming or denying the completeness of excretion once absorbed.

2 Final Report on the Safety Assessment of p-Aminophenol, m-Aminophenol, and o-Aminophenol

p-Aminophenol (PAP), m-Aminophenol (MAP), and o-Aminophenol (OAP) are used in permanent (oxidative) hair dyes at concentrations from 0.1 to 5%. In vivo and in vitro skin absorption studies indicated that 11% of the dermally applied 14C-PAP was detected in the excreta, viscera, and skin of the test animals. The oral LD50s of PAP, MAP, and OAP in rats ranged from 600 to 1300 mg/kg. Topical application of PAP at concentrations up to 8.00 g/kg to the skin of New Zealand white (NZW) rabbits produced no skin irritation and no mortality. PAP, MAP, and OAP were irritating to eyes of NZW rabbits at a concentration of 2.5%. MAP at 3% was nonsensitizing in guinea pigs; PAP at 2% sensitized 9 of 10 guinea pigs. Neither PAP nor MAP produced photosensitization in guinea pigs. No treatment-related toxicity was found in three separate four-generation chronic dermal toxicity and reproduction studies of hair dye formulations containing the three Aminophenols. Additional studies on the pure ingredients were also nonteratogenic; embryotoxicity was reported. A range of results was obtained from studies assessing the mutagenic activity of the Aminophenols. PAP tested positive in six of eight mutagenicity tests. MAP and OAP gave positive results in two of eight and five of seven mutagenicity tests, respectively. Oxidative hair dye formulations containing PAP, MAP, and OAP did not produce gross or microscopic alterations or have carcinogenic effects after chronic topical application to mice. Feeding of OAP-HCl and PAP to rats at a dose of 8 mmol/kg produced neither hepatic cirrhosis nor neoplastic lesions. A 3% solution of MAP in an aqueous vehicle was neither a significant irritant nor sensitizer in two clinical studies. A variety of epidemiological studies have not indicated that occupational exposure to, and personal use of, hair dyes containing the Aminophenols presented a carcinogenic risk. A discussion of the significance of the mutagenic data in the safety assessment and the potential for human effects is presented. On the basis of the available animal and clinical data presented in this report it is concluded that p-, m-, and o-Aminophenols are safe as cosmetic ingredients in the present practices of use and concentrations.

Urinary mutagens in cosmetologists and dental personnel

Cosmetologists are occupationally exposed to a wide range of toxic chemicals both dermally and by inhalation. Since many of these chemicals are mutagens and may be excreted in urine, the Ames Salmonella typhimurium assay was used to determine the presence of direct-acting and promutagens in the urine of practicing cosmetologists in central New York State. A comparable group (age, gender, smokers) of dental hygienists and assistants in the same geographic area was used as the control cohort. The cosmetologists had a significantly higher (39 vs. 24%, p less than .03) frequency of direct-acting urinary mutagens but there was no difference between the groups in the frequency of promutagens. In the multivariate model, cosmetologists were at two times the risk of direct-acting mutagens compared to dental workers. Smoking regularly, within 24 h of taking the urine sample, and the number of cigarettes smoked daily were not associated significantly with direct-acting mutagens in urine. Similarly, having had a hair permanent or hair dyed within 7 d of urine sampling, years of employment, age, gender and use of protective gear were not predictive of direct-acting urinary mutagens. In contrast, employment was not associated with urinary promutagens but the risk was significantly increased with increasing age and cigarette smoking. Among possible adverse health symptoms queried, only the prevalence of skin rashes differed between the cosmetologists (29%) and dental personnel (15%) (p less than .05).

Mutagenicity evaluation of HC Blue No. 1 and HC Blue No. 2. III. Effects in the Salmonella typhimurium/Escherichia coli reversion assay and the mouse lymphoma L5178Y TK+/- forward mutation assay

The hair-dye ingredients, HC Blue No. 1 (HCB1) and HC Blue No. 2 (HCB2), were tested for the induction of bacterial mutation using Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100; and Escherichia coli strains WP2uvrA-. In addition, both dyes were evaluated in the mouse lymphoma L5178Y TK+/- assay (MLA) for the potential to induce forward mutation. A liver homogenate (S9) prepared from Aroclor 1254-induced male Fischer 344 rats was used to provide a means for metabolic activation. HCB1 was not mutagenic in the Ames assay, but was weakly mutagenic in the MLA only in the presence of metabolic activation. In contrast, HCB2 was a strong mutagen in the Ames assay in tester strain TA98 both in the presence and absence of metabolic activation. A positive response was also noted with HCB2 in the MLA, both in the presence and absence of metabolic activation. Negative findings from the Ames assay of this study agree with other published results where an identical lot of HCB1 was used. Using the same lot, a weak positive result was observed in the MLA, however, the activation requirements and magnitude of the response were different from that of a lot evaluated by the NTP. In contrast, HCB2 appears to be both a bacterial and mammalian cell mutagen independent of lot variability.

Mutagenicity evaluation of HC Blue No. 1 and HC Blue No. 2, II. Effect on the in vitro induction of unscheduled DNA synthesis in rat, mouse, rabbit, hamster, and monkey primary hepatocytes

2 hair dyes, HC Blue No. 1 and HC Blue No. 2, were evaluated for the in vitro induction of unscheduled DNA synthesis (UDS) in primary hepatocytes of rat, mouse, hamster, rabbit and monkey. NC Blue No. 1, which is identified as a carcinogen by the National Toxicology Program, induced UDS in all 5 systems. HC Blue No. 2, which is identified as a non-carcinogen, induced UDS in rat, mouse, hamster and rabbit primary hepatocytes. 3-Methylcholanthrene and methyl methanesulfonate were used as positive controls to determine the sensitivity of the test system.