Although sunscreen is critical for preventing sunburns and skin cancer, some of its ingredients are not so beneficial to ocean-dwelling creatures. In particular, sunscreen chemicals shed by swimmers are thought to contribute to coral reef decline. Now, researchers reporting in ACS’ journal Analytical Chemistry say that one such chemical, octocrylene (OC), which is also in some cosmetics and hair products, accumulates in coral as fatty acid esters that could be toxic to the marine organism.