LAUSR

To the Editor, Nickel is the most common cause of contact allergy affecting 8%–19% of the adult general population and 8%–10% of adolescents and children, whereas girls and women are affected disproportionally more often. Even though nickel release from articles in prolonged contact with skin has been regulated in Europe for more than 20 years, the prevalence of nickel allergy has not decreased enough and seems to have stabilized on a high level. Market studies have repeatedly demonstrated excessive nickel release from regulated articles. This indicates that there is not enough compliance testing by companies and authorities in relation to the number of articles on the market. To counteract the unacceptably high prevalence of nickel allergy, we propose a revision of the legal requirements for metallic items placed on the European market. The current regulation is within REACH. The European Chemicals Agency (ECHA) has explained how “prolonged contact with the skin” is defined (https://echa.europa.eu/support/qas; ID 935), and which articles are under the scope of the restriction (ID 1911). In Europe, articles should comply with the European standard EN 1811, which is the reference method for showing compliance with the EU nickel restriction. According to this method, articles or metallic parts of articles are suspended in a solution of artificial sweat for a week and the transfer of nickel ions to the solution is measured. Results are reported in mass of nickel release per square centimetre and week. The legal limit is 0.5 μg/cm/week for objects with prolonged skin contact and 0.2 μg/cm/week for objects to be inserted into pierced skin. The method is complex, time-consuming, destructive, and expensive. A consequence of this is that only a small proportion of articles placed on the market is tested according to EN 1811 by authorities and business operators alike. Furthermore, over time, light has been shed on reproducibility issues with EN 1811. These include difficulties to measure the surface area of many articles, to keep the required area to volume ratio, and to analyse (separate parts of) articles made of more than one material. The dimethylglyoxime (DMG) test is a tool to test for excessive nickel release. A positive DMG test indicates, by turning cerise-red, that an article may cause nickel allergy. It has also been shown that a positive DMG test strongly indicates that the nickel release is above the limit value of 0.5 μg/cm/week. The DMG test has sometimes been criticized for limited sensitivity (false negatives), not being quantitative, and for doubtful (uncertain) results owing to discoloration (other colour than cerise-red) that may mask any cerise-red colour from nickel. Such discoloration may be caused by cobalt, copper, palladium or iron. The specificity of a positive DMG test is however generally very high (up to 98%). The DMG test has several advantages, including being quick and easy to use, cheap, suitable for articles of any surface area, size or shape, and the non-destructive procedure. The DMG test has been standardized by the European Committee for Standardization (CEN) as a screening test for nickel release, published in 2002 (CEN/CR 12471:2002), and was recently slightly revised (CEN/TR 12471:2022). The sensitivity and specificity are probably increased by CEN/TR 12471:2022, compared with the ordinary DMG test. This is achieved by additional or optional steps in the procedure, based on established knowledge on corrosion including simple pre-treatment with artificial sweat and heat; confirmation of nickel ions by dithiooxamide and abrasion of coatings are optional. We strongly urge regulators and the European Commission to add the DMG test, based on CEN/TR 12471:2022, to the test methods for assessing compliance with REACH, Annex XVII, Item 27, alongside testing with EN 1811 (preceded by EN 12472 for coated articles). We suggest that articles with prolonged skin contact and that are positive in the DMG test, should not be placed on or be immediately removed from the market. With this amendment, the compliance of articles on the market could be increased considerably, without any or much higher costs for analysis. Regulation is only efficient if compliance is sufficiently tested and enforced. We believe that this amendment would be an effective way to reduce the unacceptably high prevalence of nickel allergy in Europe.