A procedure for the determination of N-nitrosodiethanolamine (NDELA) in personal care products was evaluated in collaborative studies by member organizations of the United Kingdom's Cosmetic Toiletry and Perfumery Association (CTPA) and LGC Limited, formerly known as the Laboratory of the Government Chemist (LGC). Samples were prepared depending on the matrix of the cosmetic product: aqueous samples were prepared by diluting in water followed by solid-phase extraction; emulsions, oils and solid materials were dissolved in dichloromethane and extracted with water. NDELA was separated from the sample matrix using reverse-phase liquid chromatography. The N-nitroso bond was cleaved by photolysis to give nitrite, which was colorimetrically quantified. The nitrite functional group reacted with sulphanilamide in an acid medium to form a diazonium ion which was then coupled with N-(1-naphthyl)ethylenediamine dihydrochloride according to the Griess reaction to give a purple-coloured azo dye that absorbed at 540 nm. Compared with other published methods for NDELA, the method described here is quick and easy to use. It has the required sensitivity and specificity, and can accurately and reliably quantify NDELA in a wide range of personal care product matrices.

Synopsis A certain number of hairdressing parlour employers have been taken to court because their employees allegedly suffered from lung allergies caused by the vapours from PPD (paraphenylendiamine) which allegedly developed when applying hair dyes. These conclusions may be reached if the specific hazards of the rubber and particularly leather and fur dyeing industry are extrapolated as is widely reported in literature, to hairdressing employees. The purpose of this study is to assess the actual exposure rate to PPD vapours of hairdressing employees during a working day, on the basis of the type and characteristics of the salon (small, medium and large), the number of dye applications per day and the chemical-physical characteristics of the oxidation dyes. The results prove that, even under the hypothesis of experimental conditions pushed to the extreme, it is not reasonable to speak of exposure to PPD through the lungs of hairdressing employees.

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