Sunscreens don't cause cancer, they protect AGAINST skin cancer
Sunscreens don't cause cancer, they protect AGAINST skin cancer
Chemical sunscreens are not *less safe* than mineral sunscreens. Disinformation about sunscreen safety is a public health issue.
It’s just about Labor Day weekend, and with that, comes the unofficial end of summer for many of us here in the US. It also means many of you will be embarking on your last beach weekend hurrah of the year.
As such, it’s a perfect opportunity to address common and pervasive misinformation as it relates to sun exposure and sunscreen.
Chemical sunscreens are safe for use, don’t cause cancer or endocrine disruption, and aren’t harming coral reefs.
Fear of chemical sunscreens has been exacerbated by chemophobia and disinformation. Ironically, it is usually selective, where people spread disinformation about certain chemicals, typically the ones that they have a vested interest in demonizing.
This is most certainly the case with sunscreens, and as a result, it causes many people to not apply enough sunscreen, to try to make their own sunscreen, or to not use sunscreen at all.
Just to be clear, sunscreens protect us from UV radiation from the sun that IS a risk factor for skin cancers.
Recently, this topic got renewed attention when Andrew Huberman, yet again, covered a topic he has no expertise on and “sourced” the wrong types of experts. While this recent post from him is a shift from his previous “I'm as scared of sunscreen as I am of melanoma” it is still undermining safe and effective interventions that prevent skin cancer.
As a note: his experts for his skin health episode were dermatologists, and while dermatologists treat skin conditions, they are not the appropriate experts about sunscreen formulation, chemistry, and safety.
But this isn’t just about him. Countless accounts and media outlets circulate the same claims, undermining the safety of chemical sunscreens, and repeating the same unfounded statements. Dermatologists frequently amplify myths about risks of certain sunscreens, and even scicomm accounts that initially spoke about COVID-19 topics are repeating the same misinformation.
It’s exacerbated when anti-science groups like the Environmental Working Group (EWG) spread intentional disinformation about certain substances, scaring the public about claims related to cancer, “endocrine disruption”, and toxicity. Claims that are not supported by relevant data, but exaggerated animal studies.
Chemical AND mineral sunscreens are both safe for use. Undermining the safety of chemical sunscreens harms public health.
Why do I care about this misinformation about chemical sunscreens? Because many people don’t want to wear mineral sunscreens: the texture might be unpleasant and they cause white cast, especially on people with darker skin.
If people have been incorrectly led to believe chemical sunscreens are less safe and their *only* options are mineral sunscreens, they might not apply enough to provide adequate protection or they might not use it at all! If people are relying on false information and not using adequate protection against cancer, that’s a dangerous public health issue.
Here’s the science.
Chemical and mineral (physical) sunscreens are both chemicals.
Yes, I know. Everything is chemicals! That’s why this bothers me. But Dr. Michelle Wong and her colleagues have said this is a branding issue that isn’t going to go away anytime soon.
Scientifically, chemical sunscreens refer to organic UV filters, whereas mineral (or physical) sunscreens are inorganic UV filters. And here, organic and inorganic refer to actual chemistry, not “organic” as it is used for consumer products.
In chemistry, organic refers to chemicals that contain carbons bound to hydrogens, C-H bonds (in a nutshell, there are caveats), whereas inorganic refers to chemicals that are not carbon-based.
For example, sugars, fats, and proteins are all organic molecules, whereas table salt (sodium chloride), water, and carbon dioxide are inorganic molecules.
Mineral UV filters are inorganic chemicals that absorb UV radiation and prevent the harmful effects of exposure that can lead to cancer (which I discussed here). These include titanium dioxide and zinc oxide.
Chemical UV filters are organic chemicals that absorb UV radiation and prevent the harmful effects of exposure that can lead to cancer. These include avobenzone, octinoxate, oxybenzone, octocrylene, homosalate, octisalate, as well as Tinosorb S, Tinosorb M, Mexoryl SX, and Mexoryl XL.
Both classes of sunscreens are safe and effective.
Sunscreens do not cause cancer. What does cause cancer? Excess unprotected exposure to UV radiation.
Preferences are often based on texture, skin sensitivity, skin tone (white cast from mineral sunscreens can be more obvious on some), and unfortunately, misinformation. I’m going to focus on the misinformation, most of which is directed toward the organic sunscreens.
Both mineral and chemical sunscreens absorb UV radiation that would otherwise penetrate the skin and cause potential damage.
If you recall from my piece on UV radiation and skin cancer, the goal of sunscreens is: to take UV energy that would normally be absorbed by molecules in our skin and transfer it somewhere else.
Enter: UV filter chemicals. While there have been pervasive misconceptions about how mineral sunscreens “reflect” UV radiation whereas chemical filters “absorb” UV radiation, this is not accurate.
Both mineral AND chemical UV filters accomplish this by absorbing UV energy and convert it into heat that is released. The energy that would have penetrated your skin and potentially damaged DNA is transferred to the active ingredient molecules in sunscreens. Only about 5-10% of energy at most is reflected in the case of both types of active ingredients.
However, because of chemists like Michelle and her colleagues, the American Academy of Dermatology has updated their website to reflect this, so hopefully more will follow.
Organic sunscreens are not being absorbed by your skin and causing harmful effects.
This is the biggest and most dangerous falsehood about sunscreen, in my opinion. And it’s propped up by people like Andrew Huberman and the pseudoscientific guests he has on, including ANOTHER recent skin health episode where his expert was a dermatologist who sells sun protection supplements.
This myth gained legs because various laboratory and controlled research studies were wildly misinterpreted by anti-science groups and individuals who don’t appropriately understand chemistry, toxicology, and biochemistry.
This is a complicated discussion which Dr. Michelle Wong has beautifully summarized here, but the short version is that while minute quantities of various UV filter chemicals might be absorbed by the skin, detection does not equal relevance. Remember, the dose makes the poison with everything.
That’s why the FDA and European Commission have deemed these substances safe for use based on the levels we would be using. And the European Union has already factored in trace absorption into their safety guidance and regulations for sunscreens.
This trace absorption is not linked to any detrimental health effects. While claims about cancer and endocrine disruption (another buzzword among the anti-science activists) are rampant, there is no real-world evidence of any of these risks.
Oxybenzone is considered to be the UV filter with the greatest potential risk based on animal and Petri dish studies, but these studies are not based on real-world scenarios. Concentrations used in the laboratory are far higher than what would be applied to our skin, even if people were applying the right amount. Oxybenzone has been in use since 1978 and no harmful effects have been identified, to hormone regulation, cancer, or otherwise.
Why do I see dermatologists saying organic filters are “less safe” then?
This really speaks to the scope of expertise. While dermatologists are often the “patient-facing” skin-related professionals, they are not necessarily the scientific experts when it comes to substances applied to the skin.
Jen Novakovich, Dr. Michelle Wong, and theBeautySciComm team have excellent materials that discuss relevant expertise in cosmetic and skincare product, which is summarized here:
What this should underscore is that when it comes to science and health topics, no single person is an expert in all things on that topic. That’s why interdisciplinary teams are essential, but those teams have to include the right experts for the right goals. Dermatologists should be the primary expert in diagnosing and treating skin issues, but they are not the experts in chemical formulations, safety, ingredients, and regulations. Those roles are for scientific experts in chemistry, toxicology, and regulatory. (There are dermatologists that specifically work in safety assessment, but the ones you see undermining sunscreen safety are those that are ignoring their colleagues that specialize in that space!)
This confusion is magnified when media outlets (and prominent celebrity platforms and podcasts) use the wrong experts to cover buzzworthy topics. While people should decline to comment if something is out of their scope, we know that rarely happens.
As an aside, a recent article about insect repellent options used dermatologists as experts, who said “natural” options were effective. When tick-borne and mosquito-borne illnesses pose risks to people’s health, these falsehoods are not just annoying, they are dangerous.
Anti-science organizations like the Environmental Working Group are not credible sources of information.
It is worth reiterating that the EWG is not a credible authority on… anything. EWG has a long and lucrative history of fear-mongering about conventional produce and food products, and their chemophobia extends to other products, including vaccines, and yep, sunscreens. The EWG is an anti-science activist group, not an expert organization of relevant scientists.
EWG should never be utilized as an ‘expert source’ of information, even though they are routinely quoted by media outlets on topics related to chemicals and food.
Yes, that includes their sunscreen guide and their rating system. Ignore that, and ignore any other “apps” like Yuka that claim to do the same. They are not accurate assessments, and they are merely parroting anti-science rhetoric that scares people.
Organic sunscreens are not bad for the environment.
I was going to include this in my piece on misinformation impacting policy, but it’s better suited here. I’m sure you are familiar with the Hawaii sunscreen ban, officially Senate Bill 2571 (SB 2571), passed in 2018 and effective January 1, 2021. It prohibits sale and distribution of over-the-counter sunscreens containing oxybenzone and octinoxate in Hawaii, two organic filters used for broad-spectrum UVA and UVB protection.
This ban centered around claims that oxybenzone and octinoxate damage coral reefs. Of course, that would be a bad thing - if it were true!
But it isn’t. I bet you aren’t surprised to know that these conclusions were based on laboratory studies that used levels of these chemicals that are orders of magnitude higher than what would ever be found in an ocean based on people swimming in the water. While a 2016 study reported comparable concentrations in certain beaches, these were distant outliers - their methods were unreliable and results couldn’t be replicated. In reality, there is no consistent real-world evidence that levels of these chemicals that would wash off into water near coral reefs pose a risk.
This gained traction because of vocal outcry from activist groups like the EWG, who invested a lot of lobbying money to drive this forward. Once they get a legislator on board, it become easier to propagate falsehoods, even if they aren’t based on reality.
Climate change is what’s driving coral reef bleaching and die off.
This is the consensus from credible experts in coral science and marine biology. Coral expert Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies has repeatedly stated that people focus on the wrong things.
“People make a long list of bad things that human beings do to coral reefs — I would place sunscreen at number 200.”
Prof. Terry Hughes
But it is easier to implement performative legislation like banning chemicals that don’t pose a threat than implementing long-term and complex measures that would actually address climate change. This is the risk perception gap in action.
Ironically, this rhetoric exploits the appeal to nature fallacy. Titanium dioxide and zinc oxide are naturally-derived chemicals and are often touted as more eco-friendly.
Mineral sunscreens are not better for the environment.
Michelle and Jen tackle many common greenwashing claims in detail here. Just because something exists somewhere in nature doesn’t mean that increasing the concentration of it in nature (especially in a place it doesn’t exist) is benign. This is the same argument put forth by people advocating for organic pesticides over conventional ones (organic here is NOT the chemistry definition).
Zinc and titanium oxide can be toxic to marine life, often at equal or lower doses than organic UV filters. For similar effectiveness in a sunscreen, mineral filters are used at a higher concentration, which means that mineral sunscreens could theoretically be more of a concern for marine life. Not that there is real-world evidence of harm, but this is a common red herring fallacy.
Sourcing “natural” ingredients isn’t more eco-friendly either. Often, even though the chemicals exist in nature, those used in formulations are synthesized, just like organic filters.
The big takeaway about this is that just like other policies that are not based on science, bans on certain sunscreen ingredients is the same. And it is not doing anything to improve your health or the health of the planet.
What it does is legitimize false claims about dangers of chemical sunscreens, which may harm people’s health.
Regular use of sunscreen has been demonstrated to reduce risk of skin cancers. Data suggest that daily use of sunscreens can reduce risk of SCC by 40% and risk of BCC by 15-30%. Similarly, regular use of sunscreens with 15 SPF or higher can reduce risk of invasive melanomas by 50%.
The best sunscreen is the one you will wear.
If you prefer mineral sunscreens, wear those. If you prefer chemical sunscreens, wear those. But do not avoid one or the other because of misinformation. And do not opt out of not wearing sunscreen because you’ve been led to believe that sunscreens are causing harmful health effects. They aren’t. Excess UV exposure can though.
(The Swiss cheese model works here too: hats, UPF protective clothing, sunglasses and shade also can help reduce excess UV exposure)
Science misinformation is a public health threat.
Falsehoods about sunscreens have immediate and long-term consequences. Pervasive myths exploit chemophobia, gaps in science literacy, and ignore incredibly complex scientific processes in chemical formulation and how substances interact with our bodies. Uninformed policies impact public perception and erode trust in legitimate science and health information.
To that end, I am honored to be joining an esteemed panel at the upcoming [free] Truth in Beauty E-Summit on September 29th, so feel free to register! All of us are volunteering time and expertise to combat harmful myths that impact people’s health, policy, and more.
Thank you for supporting evidence-based science communication. With outbreaks of preventable diseases, refusal of evidence-based medical interventions, propagation of pseudoscience by prominent public “personalities”, it’s needed now more than ever.
Stay skeptical,
Andrea
“ImmunoLogic” is written by Dr. Andrea Love, PhD - immunologist and microbiologist. She works full-time in life sciences biotech and has had a lifelong passion for closing the science literacy gap and combating pseudoscience and health misinformation as far back as her childhood. This newsletter and her science communication on her social media pages are born from that passion. Follow on Instagram, Threads, Twitter, and Facebook, or support the newsletter by subscribing below:
Ohhhh this one is good!! Love that it addresses the chemical fears and effectiveness as well as the coral reefs in one!! Well done!
very informative. thanks!