Assessment of Nickel content in costume earrings sold by small-scale retailers in Kandy, Sri Lanka: Implications for consumer safety

Nickel (Ni) is used in high quantities in the costume jewellery industry as a plating material, diffusion barrier material, and a base metal. The high incorporation of Ni in costume jewellery causes nickel-induced Allergy Contact Dermatitis (ACD) in humans.  It is advisable to avoid wearing costume jewellery that exceeds the threshold limits established by the European Union Ni directive, as such items may increase the risk of causing ACD. To assess whether earring samples sold by small-scale retailers in the local market of the Kandy area comply with nickel (Ni) regulations, 180 of samples were collected at monthly intervals from five selected retailers and subjected to two tests to determine, 1) Ni content in earring samples and 2) Ni concentration released from the sample into artificial sweat solution according to EN1811: 1998, (a reference test method to determine nickel concentration released into an artificial sweat solution). An X-ray fluorescence spectrophotometer (XRF) was used as a preliminary identification technique, and the Ni concentrations were measured using a Flame Atomic Absorption Spectrophotometer (FAAS).  According to the results, out of 180 earring sample sets tested, 132 exceeded the threshold limit of 0.05% w/w for Ni content, which ranged from 0.01 µg g-1 to 4.70 µg g^-1. 104 samples exceeded the threshold limit for Ni release 0.2 µg cm^-2 week^-1 in the artificial sweat solution test, with release rates ranging from 0.04 µg cm^-2 week-1 to 317.7 µg cm^-2 week^-1. According to the results, a silver- or gold-plated outer layer does not prevent the release of Ni from the jewellery, and no direct relationship could be established between the percentage Ni content and the amount of Ni released into the artificial sweat solution. Consequently, consumers using artificial earrings from the local markets investigated in the Kandy area may be at risk of developing nickel-induced ACD.