A pilot study on the content and the release of Ni and other allergenic metals from cheap earrings available on the Italian market

Abstract

The capability of alloys used in cheap jewellery to release metal ions on contact with the skin causing allergic contact dermatitis (ACD) is generally acknowledged. To reduce the diffusion of the Ni-induced ACD the Council Directive 94/27/EC [Council Directive 94/27/EC of 30 June 1994. Official Journal L 188, 22/07/1994, 1.] limited the total Ni content in alloys and its release rate in artificial sweat. In this work, three different aspects were explored: i) the frequency of skin sensitization to Ni-containing earrings in patients before and after the introduction of the Directive's limit; ii) metal composition of alloys by X-ray analysis; iii) metal leaching in artificial sweat followed by Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS) quantification. Well-known allergenic metals, as Ni, Cr and Co, and possible emergent allergens, as Al, Ag, Au, Cd, Cu, Fe, Ir, Mn, Pb, Pd, Pt, Rh, Sn, V and Zn, were studied. Results showed that the frequency of allergy due to earrings did not decrease after the introduction of the Ni limit: in 1994 and in 2005 patients positive to Ni patch tests were 54.3% and 53.5%, respectively. The earring components analyzed were Fe-based or alloys of Cu/Zn or Fe/Cr/Ni, plated with a thin film of precious metal (Ag, Au) which, in several cases, was combined with a Ni layer beneath. Five out of 10 items were not in compliance with the Ni Directive 94/27/EC having a total Ni content > 0.05%. In three cases the release of Ni concentrations was higher than the safe sensitizing limit given by the above mentioned Regulation ( i.e., < 0.5 μg/cm 2/week). The release of Cu and Zn was very variable among the different pieces (Cu: 0.134–30.9 μg/cm 2/week; Zn: 0.141–160 μg/cm 2/week); two objects released high amounts of Fe (358 and 586 μg/cm 2/week) and one released considerable Mn (21 μg/cm 2/week). Lead was released from 70% of the objects, while Ag, Al, Cd, Co, Cr and Sn from ca. 30% of the items and concentrations of these elements were well below 0.5 μg/cm 2/week. Vanadium was released by only one item whereas Au, Ir, Pd, Pt and Rh were never leached.