Another clinical trial has shown that 6 chemical sunscreen ingredients are likely absorbed into the blood in amounts above the FDA’s recommended 0.5 ng/mL threshold levels.1 This is the second study conducted by the FDA that found active ingredients in chemical sunscreens exceed the recommended threshold, highlighting the need for further safety data.1,2
While the clinical implications of these findings are not yet known, the studies have raised some potential concerns among the general public. “Until these safety data are available, should clinicians continue to recommend the use of chemical sunscreen?” Adewole S. Adamson, MD, MPP, from the University of Texas, and Kanade Shinkai, MD, PhD, editor in chief of JAMA and from the University of California, ask in an accompanying editorial in JAMA.3
The Dermatologist has compiled the current evidence and talking points that can be used to help counsel patients while the implications of these findings is underway.
The Current Research
In February 2019, the FDA released new proposed regulations for sunscreens, which requested additional safety for 12 ingredients used in commercially available chemical sunscreens.4 This request did not apply to mineral sunscreens made with zinc oxide or titanium dioxide, which have a plethora of safety data on their use and were labeled as “generally recognized as safe and effective” by the FDA.4 Despite addressing some of the limitations of mineral sunscreens, chemical sunscreens lack sufficient safety data and thus require further investigation.
In the pilot study published in JAMA in 2019, 4 active ingredients applied under maximal use conditions (avobenzone, oxybenzone, octocrylene, and ecamsule) were found to exceed the maximal thresholds for systemic absorption (greater than 0.5 ng/mL). However, the study was conducted indoors, did not assess differences in formulation type, Fitzpatrick skin type, or age, and the sunscreen products were applied following the labeled dosage regimen, which is not reflective of how sunscreen is typically applied under real-world conditions.3,5,6
The latest study, also published in JAMA in January 2020, showed 6 tested ingredients in 4 different sunscreen formulations were absorbed in amounts above the FDA thresholds.1 This study included 48 participants randomized to 1 of 4 sunscreen products, where were applied at 2 mg/cm2 to 75% of body surface area at 0 hours on day 1 and 4 times on day 2 through 4 at 2 hour intervals. A total of 34 blood samples were collected over 21 days from each participant, which were used to measure the maximum concentrations of avobenzone, oxybenzone, octocrylene, homosalate, octisalate, and octinoxate.
Q&A: David Strauss, MD, on Systemic Absorption of Sunscreen
Active Ingredients Exceed FDA Absorption Limits for Sunscreen
Q&A: Rita Pichardo, MD, on Sunscreen and UV Protection Strategies
The researchers observed that the geometric mean maximum plasma concentrations for all 6 active ingredients were greater than the FDA threshold and exceeded it after a single application on day 1.
For lotion, aerosol spray, nonaerosol spray, and pump spray formulations with avobenzone, the overall maximum plasma concentrations were 7.1 ng/mL, 3.5 ng/mL, 3.5 ng/mL, and 3.3 ng/mL, respectively. The concentrations of oxybenzone were 258.1 ng/mL for the lotion formulation and 180.1 ng/mL for the aerosol spray. For octocrylene, the concentrations for the lotion, aerosol spray, and nonaerosol spray were 7.8 ng/mL, 6.6 ng/mL, and 6.6 ng/mL, respectively. Concentrations of homosalate were 23.1 ng/mL for the aerosol spray, 17.9 ng/mL for the nonaerosol spray, and 13.9 ng/mL for the pump spray. Octisalate concentrations for the aerosol spray, nonaerosol spray, and pump spray were 5.1 ng/mL, 5.8 ng/mL, and 4.6 ng/mL, respectively. For octinoxate, the concentrations were 7.9 ng/mL for nonaerosol spray and 5.2 ng/mL for the pump spray.
In both studies, rashes were the most common adverse event.1,2
Both studies support the FDA’s decisions to evaluate the safety of chemical sunscreens; however, the impact of these concentrations is not known. Future studies are needed to determine the clinical significance of sunscreen use, the absorption levels of sunscreen use under real-world conditions, and the long-term implications of systemic absorption.
In an editorial published in JAMA, Dr Adamson and Dr Shinkai highlighted the need for further investigation into the safety of chemical sunscreens, particularly for pediatric patients and individuals with darker skin types who may not benefit as much from sunscreen use as those with lighter skin types.3
Sunscreen, however, is a key part of sun protection. It is important to note that neither the FDA nor the authors of the editorial recommended people stop using sunscreen.1-3 For patients who are concerned about the safety of chemical sunscreens, mineral sunscreens remain a safe alternative. In addition, patients should still be using other sun protective measures, which include staying in the shade, wearing protective eyewear and hats, wearing UV protective clothing, and avoiding the sun during the hottest parts of the day.
In addition, some people may prefer “natural” products and may seek ones promoted on social media or various homeopathic websites or attempt to recreate recipes for these “natural” sunscreens at home. A 2019 study showed these recipes were not only popular on Pinterest, but also contained questionable ingredients and claims about skin cancer and sun protection that are unsupported by evidence.7
Brief Review for Patients:
- Data on the systemic absorption of sunscreen are being collected as a part of the FDA’s new rules and regulations for over-the-counter sunscreen. These studies are not questioning the efficacy of sunscreen, which is known to prevent skin cancer and sun-related aging.
- According to new findings, chemical sunscreens may be absorbed into the blood above the maximum threshold levels the FDA created for these over-the-counter products.
- The exact effects of this absorption are not known; however, the FDA does not recommend stopping the use of sunscreen.
- Sunscreen is a key part of sun protective measures, which also includes wearing UV-protective clothing, avoiding being outside during peak sun, staying in the shade, wearing hats and protective eyewear.
- Mineral sunscreens have been in use for decades and are considered generally safe and effective by the FDA. These include sunscreens made with zinc oxide and titanium dioxide.
- Natural and home-made sunscreens are not safer alternatives and do not offer the same protection as mineral or chemical sunscreens.
Additional Resources for Patients
- American Academy of Dermatology: Sunscreen Resource Center.
- American Academy of Dermatology: Is sunscreen safe?.
- CDC: Sun safety.
1. Matta MK, Florian J, Zusterzeel R, et al. Effect of sunscreen application on plasma concentration of sunscreen active ingredients: A randomized clinical trial. JAMA. 2020;323(3):256-267. doi:10.1001/jama.2019.20747
2. Matta MK, Zusterzeel R, Pilli NR, et al. Effect of sunscreen application under maximal use conditions on plasma concentration of sunscreen active ingredients: A randomized clinical trial. JAMA. 2019;321(21):2082-2091. doi:10.1001/jama.2019.5586
3. Adamson AS, Shinkai K. Systemic absorption of sunscreen: Balancing benefits with unknown harms. JAMA. 2020;323(3):223-224. doi:10.1001/jama.2019.20143
4. FDA advances new proposed regulation to make sure that sunscreens are safe and effective [press release]. Silver Spring, MD: FDA; February 21, 2019. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm631736.htm. Accessed January 23, 2020.
5. Jovanovic Z, Schornstein T, Sutor A, Neufang G, Hagens R. Conventional sunscreen application does not lead to sufficient body coverage. Int J Cosmet Sci. 2017;39(5):550-555. doi:10.1111/ics.12413
6. Petersen B, Wulf HC. Application of sunscreen--theory and reality. Photodermatol Photoimmunol Photomed. 2014;30(2-3):96-101. doi:10.1111/phpp.12099
7. Weiss M. Why dermatologists should be concerned about DIY sunscreen. The Dermatologist. https://www.the-dermatologist.com/article/why-dermatologists-should-be-concerned-about-diy-sunscreen. Published June 24, 2019. Accessed January 23, 2020.