A Closer Look at Sunscreens

Summer is here, and the time is right to buy and apply sunscreens, or at least this is the time when most Americans think about sunscreens. But deciding when, where, how much, and what kind of sunscreen to apply has become a pretty complicated business. 

The bottom line remains the same: using sunscreens can help prevent sunburn and skin damage and reduce the risk of developing skin cancer. But new research on the systemic absorption and effects of sunscreen ingredients, as well as ecological effects, is making what used to be a relatively simple choice more difficult. 

Sunscreens are formulated to work on the surface of the skin. It had previously been thought that sunscreens would not be absorbed systemically in appreciable quantities; however, a study published May 6, 2019 in JAMA, confirmed that ingredients in sunscreens are absorbed in the bloodstream. Researchers looked at four active ingredients (avobenzone, oxybenzone, octocrylene, and ecamsule) in commercially available sunscreens. Application of these four commercially available sunscreens under maximal use conditions resulted in plasma concentrations that exceeded the threshold established by the FDA. These new findings raise concerns that high levels of sunscreen ingredients in the bloodstream may lead to hormonal and other changes.

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Now, the FDA is taking a closer look at sunscreen ingredients. In February, the agency issued a proposed rule that would update regulatory requirements for most sunscreen products in the United States. The new rule would address active ingredient safety, dosage forms, sun protection factor (SPF), and broad-spectrum requirements. It also proposes updates to product labeling.

The FDA currently is seeking public comment on the proposed rule, which will address dosage safety on sprays, oils, lotions, creams, gels, butters, pastes, ointments, sticks, and powders. It is proposing sunscreen wipes, towelettes, body washes, shampoos, and other dosage forms be categorized as new drugs because of a lack of data on their safety. The agency is also raising the maximum proposed SPF value on sunscreen labels from SPF 50+ to SPF 60+.

In November 2018, Zambrana and colleagues presented new data at the American Association of Pharmaceutical Scientists PharmSci 360 Meeting showing that heat and reapplications may influence the safety and toxicity of the UV filters in sunscreens. The findings suggest that current safety testing procedures may be underestimating the amount of oxybenzone being absorbed into the skin by someone sunbathing on a beach. 

Consumers should be applying sunscreen several times a day across large portions of their body when they are out in the sun. Ingredients from sunscreens have been found in blood, urine, and breast milk. There has always been a concern that individuals may inadvertently inhale sunscreen when spraying it on or ingest some of the ingredients when applying products to their lips, potentially harming the lungs or internal organs. 

Companies commonly add a form of vitamin A to sunscreens and moisturizers with SPF. Vitamin A may help contribute to skin tumors and lesions when used on skin in the presence of sunlight. 

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Marie Perucci-Bailey, PharmD, quality and operations supervisor with the University of Virginia Health System Ambulatory Pharmacy Services in Charlottesville, says there is no current reason to recommend against the use of vitamin A in sunscreens or other skin products. “However, if a patient is concerned and would prefer a sunscreen product that does not contain a form of vitamin A, I would recommend a chemical barrier sunscreen, such as zinc oxide or titanium oxide,” she says. 

“I am not concerned about vitamin A penetration,” says Alice C. Ceacareanu, PharmD, PhD, professor of translational biomedical research management at Hartwick College, Oneonta, NY. “I am more concerned about lack of vitamin D production due to sunscreen use. Vitamin D is an anti-inflammatory molecule that protects against cancer and diabetes, and of course osteoporosis as well. Nonetheless, taking vitamin D is an option. Not applying sunscreen has far bigger consequences,” she says.

Currently, several groups of investigators are looking at whether ingredients in sunscreens may adversely affect hormonal levels, including testosterone levels in adolescent boys. Other studies have raised red flags about oxybenzone exposure during pregnancy. Perucci-Bailey does not think that the hormonal effects of sunscreens are a significant concern and that pregnant women should be advised to use sunscreens appropriately. “There is no evidence to support avoidance of sunscreens while pregnant,” she says. If a woman is concerned and wants to avoid use of sunscreens with oxybenzone or retinyl palmitate she would recommend a barrier sunscreen. 

To complicate the subject of sunscreens further, some ingredients in sunscreens may be harmful to marine animals. Researchers found octocrylene, which is also in some cosmetics and hair products, may buildup in coral and become toxic to marine organisms. Studies have shown that sunscreen ingredients shed by swimmers can contribute to coral reef decline. The state of Hawaii has banned sunscreens containing oxybenzone and octinoxate, two chemicals known to harm coral. The law takes effect in January 2021. 

Sunscreens and Skin Cancers

There is overwhelming evidence that sunscreen prevents or limits sunburn, which is what causes skin cancer. Although there is no proof that sunscreens prevent all types of skin cancers, sunscreens are still the best-known prevention. “Sunscreens are always recommended when people are going to be exposed to intense ultraviolet rays. Experts recommend that the highest possible SPF values be used to avoid painful sunburns which can cause various types of skin damage including predisposition to various skin cancers, including basal cell, squamous cell, and melanoma,” Dwight Kloth, PharmD, director of pharmacy at Fox Chase Cancer Center, Philadelphia, PA tells Drug Topics. “Children are especially susceptible and have the greatest number of years to experience the negative sequelae from a severe sunburn.” 

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Blake Phillips, MD, a dermatologist at University of Alabama at Birmingham, says there are many studies that show a protective benefit from sunscreen use for melanoma and nonmelanoma skin cancers. “There are not overwhelming numbers of large-scale long-term randomized trials, largely because running these trials would be considered unethical,” Phillips tells Drug Topics. “I encourage patients to choose a sunscreen that they will actually use.”

Sunscreens effectively protect against UV exposure, Phillips says. The majority of skin cancers arise from exposure to UV radiation which tends to be chronic, accumulating over decades. “There is a wealth of human safety data for sunscreens.” said Phillips.

Phillips says he believes pharmacists play a key role in advising patients about skin cancer prevention. They can effectively counsel patients about which medications they may be taking that are photosensitizing. 

Pharmacists also can help patients review all their drug regimens and identify any agents that may increase skin cancer risk, such as immunosuppressive medications, voriconazole, and other agents, Phillips notes. “I tend to direct children and those with sensitive skin towards the physical-blocking sunscreens. “

“Pharmacists can also reinforce proper techniques for using sunscreens,” adds Kloth.