Skin sensitization quantitative risk assessment for occupational exposure of hairdressers to hair dye ingredients.

Occupational exposure of hairdressers to hair dyes has been associated with the development of allergic contact dermatitis (ACD) involving the hands. p-Phenylenediamine (PPD) and toluene-2,5-diamine (PTD) have been implicated as important occupational contact allergens. To conduct a quantitative risk assessment for the induction of contact sensitization to hair dyes in hairdressers, available data from hand rinsing studies following typical occupational exposure conditions to PPD, PTD and resorcinol were assessed. By accounting for wet work, uneven exposure and inter-individual variability for professionals, daily hand exposure concentrations were derived. Secondly, daily hand exposure was compared with the sensitization induction potency of the individual hair dye defined as the No Expected Sensitization Induction Levels (NESIL). For PPD and PTD hairdresser hand exposure levels were 2.7 and 5.9 fold below the individual NESIL. In contrast, hand exposure to resorcinol was 50 fold below the NESIL. Correspondingly, the risk assessment for PPD and PTD indicates that contact sensitization may occur, when skin protection and skin care are not rigorously applied. We conclude that awareness of health risks associated with occupational exposure to hair dyes, and of the importance of adequate protective measures, should be emphasized more fully during hairdresser education and training.

Contact allergy to hair-colouring products: a cosmetovigilance follow-up study by four companies in Europe from 2014 to 2017.

BACKGROUND: A previous analysis of undesirable events (UEvs), reported to four major companies following the use of hair-colouring products in Europe, showed that the reporting rates were stable for both oxidative and direct hair-colouring products over the period 2003-2006. OBJECTIVES: In order to verify the impact of risk management measures implemented since 2006, as well as the impact of a new Commission Regulation (No 1223/2009), the same four companies analysed cosmetovigilance data collected over an additional four-year period (2014-2017). The objective was to determine whether there was any time effect, country effect, or product type effect, as well as identify risk factors. MATERIALS AND METHODS: Each company collected reports of alleged UEvs, undesirable effects (UEfs) and serious undesirable effects (SUEs) for their products in their key European markets, and calculated the respective reporting rates (number of events/million units sold). A detailed analysis was performed on allergic contact dermatitis-type events. RESULTS: The reporting rates for alleged UEvs and allergic-type UEfs associated with hair-colouring products remained stable over the four-year period, although a statistically significant decrease was observed for some companies. No time effect on SUEs was observed for three companies but a statistically significant decrease in SUEs was observed for one company. Black henna tattoos remained a major risk factor regarding SUEs due to hair dyes. CONCLUSION: The reporting rates of undesirable events, including contact allergy-type events, were stable over time. This was true for oxidative and direct hair dyes, for both home use and professional exposure scenarios.

Allergy Alert Test for p-Phenylenediamine-Allergic Hair Dye Users.

BACKGROUND: Contact dermatitis to hair dyes remains a health concern. Regulations in many countries require consumer self-testing for hair dyes, but no standardized procedure exists. OBJECTIVE: The aim of this study was to develop a self-test protocol for an allergy alert test (AAT) that can elicit a self-noticeable alert signal in p-phenylenediamine (PPD)-allergic consumers. METHODS: Simulating consumer use conditions (open application for 45 minutes after mixing with a developer), PPD-positive hair dye-allergic subjects and PPD-negative control subjects were tested on the forearm and behind the ear with experimental products containing 0.05%, 0.25%, 0.75%, and 2% PPD. Reactions were self-evaluated by subjects and independently assessed by dermatologists. CONCLUSIONS: The AAT caused a reaction self-noticeable on the forearm in 90.5% (38/42) and behind the ear in 93% (39/42) of the PPD-positive subjects. This was objectified by a dermatological evaluation. The strength of the AAT response and the number of responding subjects increased with increasing PPD concentrations. Allergy alert test responses were also dependent on the reaction strength of the diagnostic patch test to PPD before the study; in subjects with (+++) patch test reactions, 19 of 19 were positive. All 48 control subjects were negative to the AAT. Therefore, the AAT protocol provides a signal indicative of an allergic reaction in PPD-allergic hair dye consumers.

Optimization and characterization of an engineered human skin equivalent.

Skin equivalents (SEs) have been designed to meet both basic and applied research needs. The successful application of tissue-engineered SEs requires that the reconstituted tissues be endowed with the correct organization and function. A large body of experimental evidence now supports the notion that the inducing effects of mesenchymal tissue on epithelial cell morphogenesis are mediated, at least in part, by extracellular matrix components in addition to cell-cell interactions. A coculture model including both fibroblasts and keratinocytes was used to study the effects of progressive serum reduction on epidermal differentiation, quality of dermal and dermal-epidermal junctions, and expression of extracellular matrix proteins. The cells were successively added to a dermal substrate composed of collagen, glycosaminoglycans, and chitosan. The main aim of this study was to optimize this model for pharmacotoxicological trials. Control skin equivalents were cultured with medium containing 10% serum throughout the production process. Serum content was reduced to 1 and 0% at the air-liquid interface and compared with control skin equivalents. First, we demonstrated that serum deprivation at the air-liquid interface improves keratinocyte terminal differentiation. Second, we showed that, in the absence of serum, the specific characteristics of the SE are maintained, including epidermal and dermal ultrastructure, the expression of major dermal extracellular matrix components (human collagen types I, III, and V, fibronectin, elastin, and fibrillin 1), and the dermal-epidermal junction (laminin, human type IV collagen, alpha6 integrin). Furthermore, our results indicate that coculture models using keratinocytes and fibroblasts have both morphological and functional properties required for biologically useful tissues.