What you've heard
Sunscreen is dangerous, and you are better off without it
Verdict
The danger claim is unsupported, and the one long trial runs the other way
Is sunscreen dangerous?
The danger claim is unsupported, and the one long trial runs the other way.
In trials run by the US Food and Drug Administration, heavy, repeated use put several chemical filters into the blood above the level that prompts further safety testing. The agency has not concluded that those ingredients are unsafe. Against that sits a randomized trial in Nambour, Queensland, where adults were assigned to put on sunscreen every day or as they pleased. The daily group developed about two-fifths fewer squamous cell tumors, though no fewer people got one, and a decade after the trial ended, it had three invasive melanomas against eleven, a small count.19 If the worry is vitamin D, a daily supplement settles it without giving up sunscreen. If you want less on your skin, lean on shade, clothing and a hat first.
Where the book tests it
Sources
- 19.Matta, M.K., Zusterzeel, R., Pilli, N.R., Patel, V., et al. (2019). "Effect of sunscreen application under maximal use conditions on plasma concentration of sunscreen active ingredients: a randomized clinical trial." JAMA, 321(21), 2082-2091. https://doi.org/10.1001/jama.2019.5586 ; U.S. Food and Drug Administration (2026). Questions and answers: FDA's regulatory actions on over-the-counter sunscreen. https://www.fda.gov/drugs/understanding-over-counter-medicines/questions-and-answers-fdas-regulatory-actions-over-counter-sunscreen ; Green, A., Williams, G., Neale, R., Hart, V., et al. (1999). "Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial." The Lancet, 354(9180), 723-729. https://doi.org/10.1016/S0140-6736(98)12168-2 (1,621 adults. Tumors, rate ratio 0.61; people with a new squamous cell cancer, 0.88, 95% CI 0.50-1.56.) ; Green, A.C., Williams, G.M., Logan, V., and Strutton, G.M. (2011). "Reduced melanoma after regular sunscreen use: randomized trial follow-up." Journal of Clinical Oncology, 29(3), 257-263. https://doi.org/10.1200/JCO.2010.28.7078 (Invasive melanoma hazard ratio 0.27, 95% CI 0.08-0.97; all melanomas 0.50, 0.24-1.02.)
Note numbers are those of Chapter 7, Light and Dark.
This verdict is one of the "What you've heard" boxes in Chapter 7, Light and Dark, where the book tests the claims people repeat against the studies behind them.
Educational content, not medical advice. Disclaimer.