Does cobalt spot testing of copper items result in false‐positive test reactions?

Thyssen, Jacob P.; Johansen, Jeanne Duus; Menné, Torkil; Jellesen, Morten Stendahl

doi:10.1111/cod.12158

Cited by 2 publications

(2 citation statements)

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“…The cobalt spot test is relatively new , and interference by other metals or materials has been reported . In this study, we found green and/or rust‐like discolouration in metal parts with high iron contents, and light brown discolouration caused by nickel or copper.…”

Section: Discussionmentioning

confidence: 49%

Nickel and cobalt release from fidget spinners on the Danish market

et al. 2018

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Fidget spinners, which are toys used by children of school age, became very popular in 2017. During normal use, they are in direct and prolonged contact with the skin on the hands. Fidget spinners may have metals parts, and therefore represent a potential source of metal contact allergy and thus allergic contact dermatitis. The aim of this study was to screen a random selection of fidget spinners on the Danish market for nickel and cobalt release. MethodsIn July to August 2017, M.G.A. purchased, avoiding duplicates, 41 random fidget spinners from a wide variety of stores: toy stores (n = 10), on the internet (n = 10), accessory stores (n = 9), markets (n = 4), bookshops (n = 2), Danish discount design chains (n = 2), a greengrocer (n = 1), a supermarket (n = 1), a sports shop (n = 1), and a piercing and tattoo studio (n = 1). In total, we spent €440, and the price varied from €2.7 to €23. The dimethylglyoxime (DMG) test and the cobalt spot test were used for screening of nickel and cobalt release, respectively (1, 2), as previously described (3), in our laboratory at the Department of Dermatology and Allergy. The DMG result was classified as positive (pink), negative (no colour change), or doubtful (discolouration other than pink). All locations with doubtful reactions were retested: a remaining doubtful test reaction was classified as doubtful. The cobalt spot test was performed before the Correspondence: MD Malin Glindvad Ahlström, DMG test to decrease the risk of false-positive reactions (1). The fidget spinners were placed on a non-woven swab (Curi-Med; Abena, Aabenraa, Denmark), ∼50 ml of cobalt spot test solution was poured over them, and the result of the test was read after ∼20 min. Also, metal parts that were not considered to be in direct contact with the swab were tested with one drop of the cobalt spot test solution on a cotton stick and rubbed for 30 seconds (1). The test result was classified as positive (orange-red), negative (yellow), or doubtful (light brown to rust-like). If the cobalt spot test had resulted in a colour change, the fidget spinner was rinsed with tap water before DMG testing.Qualitative analysis with X-ray fluorescence (XRF) (Maxxi 6, 2016, S/N 21G1627; Oxford Instruments, Taunusstein, Germany) was performed on 10 spinners with a positive or doubtful spot test reaction, or with a green discolouration with the cobalt spot test, at the Technical University of Denmark. One aluminium-containing spinner was analysed with a TM3000 Tabletop Microscope (Hitachi, Tokyo, Japan) equipped with a Bruker (Berlin, Germany) Nano energy dispersive spectroscopy (EDS) detector (product ID 2107; Serial no.: 0357). All metallic sites considered to be in direct contact with the hands, that is, the centre pad (where fingertips are placed) (Fig. 1b), the wings (arms) (Fig. 1b), and the outer bearings of the wings ( Figure S1b), were tested. Also, the centre ball bearing (under the centre pad) ( Figure S1a) was tested, as it was made of metal. Parts that were visibly made from plastic were not tested. Re...

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Section: Discussionmentioning

confidence: 49%

Nickel and cobalt release from fidget spinners on the Danish market

et al. 2018

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“…The cobalt test was only recently developed, and experience with it is still limited. It is a test that may be more difficult to interpret than the dimethylglyoxime test for nickel ; however, it is a step forwards to have an easily accessible tool for exposure assessment that may help in filling the remaining gaps of knowledge about cobalt exposures. An updated table of known cobalt exposure sources has recently been published .…”

Section: Discussionmentioning

confidence: 99%