Permanent hair dyes. Exposure, diagnostics, and prevention of contact allergy.

Permanent hair dyes are widely used for hair coloring and the substances used are often well known sensitisers, causing contact allergy and dermatitis in hairdressers and consumers. The aromatic amines p-phenylenediamine (PPD) and toluene-2,5-diamine (TDA) are both important components of permanent hair dyes and extremely strong sensitisers. The prevalence of contact allergy to PPD in the general population in Europe was reported to be 0.8%. Allergic contact dermatitis may especially in those colouring their hair have very dramatic clinical appearance, sometimes giving rise also to systemic reactions. Due to the daily exposure to skin irritants and contact allergens as permanent hair dyes ingredients, hairdressers have an increased risk of developing occupational hand eczema, which often can be a reason to leave the profession. Exposure: one of the aims of this thesis was to investigate the exposure to known sensitizers in hairdyes in products bought in different countries and on the internet. We performed chemical analisys of the most important allergens (PPD and 2,5-TDA) in 52 samples of permanent hair dyes. The findings of the chemical analysis were compared with the labelling of the products. The products purchased in Europe contained concentrations of PPD and 2,5-TDA within the limits stated by the European Union (EU) regulations, whereas the concentration of PPD in products purchased outside Europe were higher and in two cases exceeded up to four times the limits of the EU regulations. Diagnostics: the aim of study IV was to improve patch testing, trying to find the best patch test preparations (also with regard to chemical form and concentration) for the hair dye allergens PPD and 2,5-TDA. We tested 2,477 consecutive dermatitis patients at the Department of Occupational and Environmental Dermatology (DOED) in Malmö with two different groups of hair dye ingredients. As has been found previously PPD was the best hair dye marker. The patch test concentration of 1.0% in petrolatum (pet.) should remain as patch test preparation in the baseline series. The free forms, PPD and 2,5-TDA, trace more contact allergy than the respective salt. The patch testing with 2,5-TDA can be optimised and should be considered within the hairdressers series and when the suspicion of hair dye allergy is raised especially in countries where exposure to 2,5-TDA or 2,5-TDA sulphate (2,5-TDA-S) is more common than PPD. Prevention of contact allergy: in studies I and III, we investigated in vivo the performance of protective gloves used by hairdressers, mimicking their exposure to chemicals during the hair dye procedure with oxidative dyes. In study I we observed poor protective performance by many of the glove materials commonly used by hairdressers (natural rubber latex, polyvinyl chloride, polyethylene), when tested with a permanent hair dyes containing PPD in PPD-sensitised individuals. Nitrile gloves showed an excellent performance even at the longest exposure time of 60 minutes. In study III, the same in vivo provocation test system was used to test 3 different professional hair dyes (containing PPD, 2,5-TDA-S, and 2-methoxymethyl-PPD, respectively) and an hair dye intended for home-use (containing 2,5-TDA-S) with different glove materials in volunteers allergic to PPD and 2,5-TDA. We found that nitrile gloves protect efficiently against all the hair dyes tested. Nitrile gloves can thus be recommended to hairdressers and customers to protect the skin during hair dyeing tasks. The polyehtylene gloves provided in the package of the hair dye for home-use protected the skin against the recommended hair dye in the sold kit.