Research from the Department of Environmental Health Sciences explores how common sunscreen ingredients behave under light exposure. Led by associate professor Eric Vejerano, the team tested seven commercially available sunscreens (including four mineral-based formulas) and found that every sample produced persistent free radicals (PFRs) when exposed to artificial light. The study, published in Environmental Science & Technology Letters, provides new insight into sunscreen photochemistry and may help guide future evaluations of product performance and safety.