Nickel exposure when working out in the gym.

In order to decrease the burden of contact allergy, release of nickel from products intended for direct and prolonged contact with the skin has since the year 2000 been limited to 0.5 µg Ni/cm 2 /week in the European Union. This is according to the former EU Nickel Directive, which is part of the EU chemicals regulation REACH since 2009 (1). The restriction has resulted in some reduction of the prevalence of nickel allergy, especially in young females (< 30 years) both in the general population and in dermatitis patients. Prevalence data from North Ame-rica and Western Europe show that nickel allergy is still frequent; approximately 17% of women and 3% of men in the general population are allergic to nickel (2). One reason for this might be that there are still several items on the market, including jewellery, that release nickel (3, 4). Also there are several items that come in brief and repeated contact with the skin that are not covered by the legislation. Examples are tools, keys, laptops and coins (4, 5). The nickel legislation restricts only the amount of nickel that is released from objects and not the actual skin dose (µg Ni/cm 2) of nickel, which is the key factor for developing contact dermatitis (6). To measure the dose of nickel exposure on the skin, different methods for quantification are available such as acid wipe sampling and the finger immersion method (7, 8), requiring an advanced chemical analysis after collection of samples. A spot test, dimethylglyoxime (DMG) test, is available for quick screening of items (Fig. 1). Its sensitivity around the limit value (0.5 µg Ni/cm 2 /week) is 59.3% and the specificity 97.5%, based on concentration determined by the EN 1811 reference method. It was shown that the DMG test may serve well for screening purposes (9), also to assess presence of nickel on the skin (10). Recently, an epidemic of acute dermatitis from a fitness wristband (Force Activity-Tracking Wristband, Fitbit Inc.) was experienced in North America and the product was retracted (https://www.cpsc.gov/en/