What is the superior choice between mineral-based sunscreen, chemical sunscreen, or no sunscreen at all?
Despite the acknowledged benefits of sunscreen, discussions about its safety and necessity have lingered for years. This controversy has been partly fed by an escalating number of social media influencers and the 2021 detection of carcinogen benzene in some recalled sunscreens. The benzene appeared to be linked to the aerosol propellant rather than an ingredient in sunscreen. Moreover, the US Food and Drug Administration pushed for manufacturers to conduct more safety research on a dozen common sunscreen components.
Separating fact from fiction and determining what warrants worry can sometimes be challenging.
The connection between sun exposure and skin cancer is well-established. Ultraviolet radiation is believed to be responsible for up to 95% of basal and squamous cell carcinomas, and between 70-95% of melanomas in individuals with fair skin.
As Dr. Rachel Neale, a researcher at QMR Birkhoff in Brisbane, Australia, explained to CNN Medical Correspondent Meg Tirrell during a recent episode of the podcast Chasing Life, skin cancer is caused by UV radiation exposure, particularly UVB radiation. Exposure of skin cells to these harmful rays can lead to mutations in DNA, which can in turn result in more mutations and potentially cause skin cancer.
Since the 1990s, it has been known that sunscreen helps reduce the risk of developing skin cancer, especially melanoma and squamous cell carcinoma. Basal cell carcinoma, the most common type of skin cancer, though rarely fatal, can cause distress and disfigurement.
Ingredients under scrutiny
However, there are now concerns about the safety of certain sunscreen ingredients.
Sunscreen can be classified into two types: mineral (also known as physical) and chemical. "The physical blockers — so the titanium and zinc sunscreens — they sit on top of the skin and form a barrier," explained Neale. "On the other hand, chemical sunscreens bind to the top surface of the skin and convert UV radiation into heat, which then disperses from the body’s heat."
The FDA, which regulates sunscreen as a non-prescription drug, requested additional safety data on 12 common ingredients from sunscreen manufacturers in 2019 and 2021, aiming to establish GRASE (Generally Regarded As Safe and Effective) status for them.
The FDA's request is motivated by two factors. First, when scientists initially evaluated sunscreens in the 1970s, they were not fully aware of how readily chemicals could be absorbed through the skin. Today, transdermal application is a common delivery method for certain medications, such as nicotine, pain, and hormone patches.
Second, the recommended sunscreen application amount has increased significantly over the years, from a few dabs here and there to a shot glass-full every two hours spent outside. "If used as intended, which would make it effective, there's a lot more of it that's ending up in our bloodstream than we realized, and the concern is that we don't know enough about its safety," said researcher Laura Vandenberg. Vandenberg is a professor of environmental health sciences at the University of Massachusetts Amherst and studies endocrine disruptors.
The FDA has asked sunscreen manufacturers to conduct studies where the sunscreen is used as intended and measure how much of these chemicals end up in the bloodstream. The FDA has standards for the amount of these chemicals that should be present in the bloodstream, and currently, they are unable to meet both the safety and effectiveness criteria.
Vandenberg has raised concerns about certain ingredients, including oxybenzone, which she studies in her lab. Studies in cell cultures and research animals indicate that the chemical can mimic estrogen, block androgen's actions, and alter thyroid hormone function, which could potentially have negative consequences in vulnerable populations, such as children, pregnant women, or those going through puberty.
Disruptions to hormones can lead to life-altering changes and increased disease risk, sometimes appearing decades later in humans. However, some critics argue that there is no evidence to suggest that these chemicals can cause harm in human populations. Vandenberg counters this by citing studies that show exposures to oxybenzone are associated with increased neurodevelopment problems in children, metabolic issues in children, and increased thyroid hormone issues in adults.
Vandenberg acknowledges that linking something to a result, like oxybenzone causing specific effects, isn't automatically true just because they're linked. She explains, "So, is it true that a chemical like oxybenzone causes those effects in people? No, because we're not intentionally exposing some individuals to oxybenzone while avoiding those who've never been exposed to it (since such people don't exist)."
Credit goes to the FDA for requesting more safety investigations, says Vandenberg. She asserts that just because certain sunscreen ingredients pass through the skin doesn't inherently mean they're hazardous. In her opinion, "I think what they're really signaling is that there isn't enough evidence to declare them dangerous. Yet, when it comes to products we slather on our bodies, or those of our kids, we're seeking assurance of safety and effectiveness."
When it comes to protecting themselves, both Vandenberg and Neale agree on the necessity of sunscreen. Neale opts for chemical sunscreens daily, explaining, "Chemical sunscreens are more comfortable to use due to their properties. Physical blockers, on the other hand, can be thicker and leave a white sheen on the skin." She also emphasizes the importance of clothing as a barrier and avoiding sun exposure during its most intense period.
Vandenberg, meanwhile, leans towards physical sunscreens in her personal practice. "Given what I know, I prefer physical sunscreens and use appropriate amounts, reapplying every 90 minutes. It's better to use something than nothing at all when it comes to skin cancer," she said, acknowledging the presence of these chemicals everywhere. "I worry that endocrine disruptors are in sunscreen products, but they're also prevalent in almost everything around us. Removing that one product may not lessen your risk of endocrine disruptions, while simultaneously increasing your risk of skin cancer isn't wise."
She concludes by urging for safer products and demanding it from consumer companies and regulatory agencies.
Maintaining good health is essential to minimize the risks associated with skin cancer. Regularly applying sunscreen can significantly reduce the chance of developing melanoma, squamous cell carcinoma, and basal cell carcinoma.
Despite the health benefits of sunscreen, there are concerns about the safety of certain ingredients, leading regulatory bodies like the FDA to request more research on their effects.
