Assessment of Content and Release of Nickel, Cobalt and Lead in Metallic and Rhinestone Nail Charms in the United States

BACKGROUND: Metallic nail adornments and other charms are increasingly popular additions to traditional nail treatments. Nickel and cobalt are well-recognised causes of allergic contact dermatitis (ACD) in jewellery and other daily consumer exposures. Nickel-releasing nail charms complicating acrylate allergic contact dermatitis in a young woman have been reported. No current studies have evaluated the presence of nickel and cobalt in metallic nail charm products in the United States. OBJECTIVE: To assess nickel and cobalt release and total metal content with x-ray fluorescence spectroscopy (XRF) from nail charm products available in the United States. METHODS: Convenience samples of nail charm products were obtained from nail supply stores in Arizona, Nevada and online retailers. Nickel and cobalt content and release were assessed in 231 nail charms from 25 nail product brands by spot tests and XRF, respectively. In charms with lead content assessed by XRF, confirmatory spot testing was performed. RESULTS: Nickel release was detected in 89/231 (38.5%) products by dimethylglyoxime (DMG) spot test and 156/231 (67.5%) products by XRF. Cobalt release was not detected. Lead was detected in 5/231 (2.2%) products by XRF and 2/231 (0.87%) by spot test. CONCLUSIONS: Nickel release is common from nail charm products purchased in the United States, which could be an emerging novel source of consumer and occupational nickel exposure. Lead was also detected in a small subset of charms, indicating that nail charms may be a rare but emerging source of exposure to lead.