Matthews NH, et al. - Among participants from the Nurses' Health Study (1984-2012) and the Health Professionals Follow-up Study (1986-2012), including 6,708 women and 3,730 men, respectively, researchers investigated the link between toenail trace element levels and skin cancer risk. They measured toenail levels of mercury, selenium, chromium, iron, and zinc among participants. At toenail collection, skin cancer was not present among study participants. For incident basal (BCC) and squamous cell carcinoma (SCC), and melanoma, a follow-up was performed for 26-28 years, which revealed 2,433 BCC, 334 SCC, and 130 melanoma cases. Increased skin cancer risk was observed in relation to increased toenail mercury concentrations, as revealed by prospective data. Only females demonstrated a positive association of chromium with BCC. Findings revealed no links between other metals and skin cancer risk.