Systematic review on skin adverse effects of important hazardous hair cosmetic ingredients with a focus on hairdressers.

BACKGROUND: The burden of occupational hand eczema in hairdressers is high, and (partly strong) allergens abound in the hair cosmetic products they use. OBJECTIVES: To systematically review published evidence concerning contact allergy to an indicative list of active ingredients of hair cosmetics, namely, p-phenylenediamine (PPD), toluene-2,5-diamine (PTD), persulfates, mostly ammonium persulfate (APS), glyceryl thioglycolate (GMTG), and ammonium thioglycolate (ATG), concerning the prevalence of sensitization, particularly in terms of a comparison (relative risk; RR) between hairdressers and non-hairdressers. METHODS: Following a PROSPERO-registered and published protocol, eligible literature published from 2000 to February 2021 was identified, yielding 322 publications, and extracted in standardized publication record forms, also considering risk of bias. RESULTS: Based on 141 publications, the contact allergy prevalence to PPD was 4.3% (95% CI: 3.8-4.9%) in consecutively patch tested patients. Other ingredients were mostly tested in an aimed fashion, yielding variable, and partly high contact allergy prevalences. Where possible, the RR was calculated, yielding an average increased sensitization risk in hairdressers of between 5.4 (PPD) and 3.4 (ATG). Additional evidence related to immediate-type hypersensitivity, experimental results, exposures, and information from case reports was qualitatively synthesized. CONCLUSIONS: An excess risk of contact allergy is clearly evident from the pooled published evidence from the last 20 years. This should prompt an improvement in working conditions and product safety.

Factors associated with p-phenylenediamine sensitization: data from the Information Network of Departments of Dermatology, 2008-2013.

BACKGROUND: Risk factors for p-phenylenediamine (PPD) sensitization include the use of hair dyes, the application of temporary black henna tattoos, working as a hairdresser, and, possibly, exposure to hair dye pretests. OBJECTIVES: To quantify the impact of these (putative) risk factors on PPD sensitization. METHODS: Six items related to PPD exposure were added to the routine Information Network of Departments of Dermatology questionnaire from 2008 to 2013. A retrospective analysis of data from 4314 patients tested with PPD 1% pet. was conducted. RESULTS: Of the PPD-positive patients (n = 271), 80% had their hair dyed, and, of these, 57% subsequently developed scalp dermatitis, whereas only 11% had had a henna tattoo. The self-administrated pretest with hair dye was performed by only a few patients, precluding a more detailed analysis. Hair dyeing [odds ratio (OR) 6.0; 95% confidence interval (CI): 3.9-9.4], henna tattoos (OR 2.4; 95%CI: 1.5-3.7) and being a hairdresser (OR 2.1; 95%CI: 1.3-3.2) increased the risk of PPD sensitization. Neither dyeing of own hair nor application of a temporary henna tattoo seemed to affect PPD sensitization in hairdressers. p-Aminoaryl compounds more often gave positive reactions in patients with henna tattoo. CONCLUSIONS: Hair dyeing is the major risk factor for PPD sensitization in this clinical setting, and application of a temporary black henna tattoo may also lead to (strong) PPD sensitization.

ESSCA results with the baseline series, 2002-2012: p-phenylenediamine.

BACKGROUND: Allergic contact dermatitis caused by p-phenylenediamine (PPD) is common among all age groups and both sexes. Monitoring of prevalence and intensity of sensitization is important. OBJECTIVE: To evaluate contact allergy to PPD in Europe, and to compare reaction intensities in different European regions. METHODS: Data collected by the European Surveillance System on Contact Allergies (ESSCA) network between 2002 and 2012 from 12 European countries were analysed regarding prevalence, grading of positive reactions to PPD, and relevance. RESULTS: A total of 99 926 PPD-positive patients from 63 departments were included for analysis. The overall (2002-2012) prevalence of PPD sensitization in Europe is ∼4%. Stratified for country, the highest overall standardized prevalence was found in Lithuania, and the lowest in Slovenia. The prevalence of PPD sensitization did not decline over the years. In the southern European countries, higher numbers of strong and extremely strong reactions were registered. The clinical relevance of PPD sensitization varied from half to three-quarters. CONCLUSION: The prevalence of PPD sensitization has not changed over time. Strong and extremely strong patch test reactions are seen more often in the South, probably because of the higher number of PPD-containing hair dye products.

The role of the antioxidant ascorbic acid in the elicitation of contact allergic reactions to p-phenylenediamine.

BACKGROUND: An allergic contact reaction is accompanied by high oxidative stress in the skin. Pretreatment of the skin with antioxidative substances could reduce the elicitation reaction. OBJECTIVES: To investigate, in a proof-of-principle study, whether pretreatment of the skin with the antioxidant ascorbic acid reduces the elicitation reaction to a p-phenylenediamine (PPD)-containing hair dye in sensitized subjects. METHODS: Twelve subjects with contact allergy to PPD, a documented skin reaction to a hair dye simulation exposure model and a history of hair dye-related skin complaints were included in this study. Skin areas on the forearms were, in a left versus right design, exposed to an emulsion with ascorbic acid and an emulsion without ascorbic acid, and then to a 2% PPD-containing hair dye testing formulation. In addition, control areas were exposed to the emulsions and to the PPD-containing hair dye formulation without pretreatment. Skin reactions were graded on day (D)2 and D3. RESULTS: Pretreatment with ascorbic acid emulsion resulted in a reduction in the elicitation reaction in 7 of 12 subjects at D3 (p = 0.046). No statistically significant difference was observed at D2. CONCLUSIONS: Pretreatment of the skin with the antioxidant ascorbic acid had an attenuating effect on the elicitation reaction to PPD in sensitized individuals.