The endless debate about sunscreen safety

By Maggie Staszcuk

Sunscreen safety has long been debated, with the dangers of chemical ingredients weighed against the dangers of long-term sun exposure. In addition to entering the blood stream, chemical ingredients found in some sunscreens have been found to cause hormone disruption, trigger allergies, be carcinogens, or have other immune effects. In addition to these potential health risks, the sale of chemical-based sunscreens have been banned in Hawaii, where they have been shown to damage and kill coral reefs. 

In January 2020, the FDA published a study in the Journal of American Medical Association (JAMA) that tested 12 chemicals commonly found in sunscreens. All 12 chemicals entered the bloodstream after one use and were found at levels that surpassed the FDA’s threshold for safety. The chemicals were also found to stay in the body for up to 21 days. 

Mineral sunscreens are considered a safer alternative, but even these have come under scrutiny. Zinc and titanium dioxide, also referred to as mineral filters, are the two ingredients approved to reflect and refract UV photons to prevent sunburn. In 2021, zinc and titanium dioxide were granted the GRASE designation by the FDA. This designation stands for “generally recognized as safe and effective.” These were the only two out of 16 ingredients evaluated to receive this designation. Although recognized as generally safe and effective, zinc and titanium dioxide are often used in powder form, sprays, and aerosols, which may increase the potential for exposure through inhalation and therefore making them a carcinogen. The FDA proposed additional tests and standards for sunscreens in these forms to ensure no nanoparticles are released that could damage the lungs when inhaled.  

Because zinc and titanium dioxide are known to leave a white cast on skin, manufacturers have adopted the use of nanoparticles to create a mineral-based product that is effective and more translucent. By reducing the particle size of zinc and titanium dioxide, the resulting formula is more translucent, and the white cast previously left on skin has been eliminated. 

But the use of nanoparticles isn’t the only feature that can increase the spread and performance of a sunscreen. Butyloctyl salicylate (BOS) is a booster responsible for the silky feel of mineral formulas and can increase a sunscreen’s protection level against UV rays. However, the safety of this ingredient has also been called into question. 

To achieve an SPF rating higher than 30 in mineral form, manufacturers must include a booster.  Boosters improve a sunscreen’s ability to block UV rays without actually doing the blocking themselves. BOS is structurally similar to the chemical ingredient octisalate, one of the 12 ingredients reviewed and listed in the FDA’s 2020 study. Manufacturers have argued that boosters are inactive compounds, since they are not actively blocking UV rays and so do not have to provide the concentration on the ingredient dec. It’s argued that including an ingredient that closely resembles a chemical sunscreen in a mineral block formulation is misleading. 

As with any skin product—especially ones we may use or recommend to our clients—it’s important to stay informed about a sunscreen’s safety as well as its efficacy. Knowing a product’s ingredients and staying up to date on studies and research about those ingredients is the best way for you and your clients to choose the best products for them. After all, we all want to have a safe and happy summer. 

Interested in more content like this? Tune in to ASCP's Esty Talk Ep 264, Is There a Perfect Sunscreen, where hosts Ella and Maggie discuss UV filters and boosters, and share their take on sunscreen safety. 

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