FDA-sponsored trials showed that several sunscreen active ingredients enter plasma. Absorption is not evidence of harm, and the 0.5 ng/mL threshold triggers a request for more safety data rather than defining toxicity.[1]
What the absorption trial measured
In a randomized maximal-use study, avobenzone, oxybenzone, octocrylene, homosalate, octisalate and octinoxate exceeded 0.5 ng/mL. The study measured pharmacokinetics, not disease or toxicity.[1]
Do not turn absorption into a harm claim
The measured blood concentrations do not show endocrine injury, cancer or reproductive harm. They show that more safety data are required under FDA's framework.[1]
Sun protection has demonstrated benefit
A randomized trial found fewer squamous-cell tumors with daily sunscreen use. Follow-up found fewer invasive melanomas, although event counts were small. These benefits matter when considering uncertain ingredient concerns.[2] [3]
Choose a sunscreen you will use
Keep using broad-spectrum sunscreen as part of sun protection. Mineral formulas are an option, not proof that organic filters are harmful. FDA also added bemotrizinol to the US monograph in June 2026 under specified conditions.[2] [4] [5]
Sources for this article
Each source below states the claim it supports and the limits of that evidence.
Matta MK, Florian J, Zusterzeel R, et al.. 2020. Effect of Sunscreen Application on Plasma Concentration of Sunscreen Active Ingredients: A Randomized Clinical Trial. JAMA. DOI: 10.1001/jama.2019.20747. PMID: 31961417.
Supports: Six tested UV filters exceeded the FDA 0.5 ng/mL threshold under maximal-use conditions. That threshold requests more safety data and is not a toxicity threshold.
Evidence class: Human randomized pharmacokinetic trial
Green A, Williams G, Neale R, et al.. 1999. Daily Sunscreen Application and Betacarotene Supplementation in Prevention of Basal-Cell and Squamous-Cell Carcinomas of the Skin. Lancet. DOI: 10.1016/S0140-6736(98)12168-2. PMID: 10475183.
Supports: A randomized community trial found fewer squamous-cell tumors with daily sunscreen use. Basal-cell carcinoma was not significantly reduced.
Evidence class: Human randomized prevention trial
Green AC, Williams GM, Logan V, Strutton GM. 2011. Reduced Melanoma after Regular Sunscreen Use: Randomized Trial Follow-Up. Journal of Clinical Oncology. DOI: 10.1200/JCO.2010.28.7078. PMID: 21135266.
Supports: Trial follow-up found fewer invasive melanomas in the daily-sunscreen group, although event counts were small.
Evidence class: Follow-up of a human randomized trial
Centers for Disease Control and Prevention. n.d.. Title not stated in the supplied verified corpus. Centers for Disease Control and Prevention.
Supports: CDC recommends broad-spectrum sunscreen together with shade, protective clothing and hats.
Evidence class: Federal public-health guidance
US Food and Drug Administration. 2026. Final Administrative Order OTC000039. US Food and Drug Administration.
Supports: FDA added bemotrizinol to the US sunscreen monograph in June 2026 at up to 6% under specified conditions.
Evidence class: Final federal administrative order