Endocrine Disruptors in Sunscreen (plus the rest of the story)
You may be wondering why the sudden media attention around sunscreens. There are three big reasons.
Chemical sunscreens penetrate your skin at problematic rates
First, FDA conducted a study which was published in The Journal of American Medical Association in May 2019. In this study, FDA found that a number of sunscreens can penetrate your skin and wind up in your bloodstream. This was a very small study, only 24 participants, and for each study arm, 6 participants applied one of four sunscreens containing avobenzone. Regardless of the formulation, avobenzone was tested in the blood of these participants.
In another 1-year study led by NHANES (National Health and Nutrition Examination Survey) in 2003/2004, chemical sunscreens also referred to as UV filters were found to rapidly absorb into your skin. This study found oxybenzone (also known as benzophenone-3) in 96% of more than 2500 urine samples collected in America, and this supports that oxybenzone is ubiquitous in our environment.
A number of UV filters including benzophenone and octinoxate are common in wastewater and surface water, and some like benzophenone persist in soil.
A number of UV filters can make their way into breast milk as demonstrated by a study in women conducted in Switzerland and published in 2010.
Chemical sunscreens have endocrine disrupting potential (along with other characteristics that make them a health concern)
Here are just a few examples.
Benzophenone is a class of sunscreen additives. Oxybenzone is approved for use in the EU, US, and Australia. It can be used at levels up to 6% in the EU and up to 10% in both America and Australia.
From an endocrine disruption standpoint, oxybenzone has been found to disrupt normal hormonal levels of testosterone during male development in both mice and rats. It accomplishes this by inhibiting androstenedione’s conversion to testosterone. BP-3 can also completely inhibit dihydrotestosterone activity in a concentration-dependent fashion. Octocrylene and octinoxate were also found to inhibit dihydrotestosterone in a dose-dependent manner.
According to a study published in 2018, octylmethoxycinnamate (ethylhexyl methoxycinnamate or octinoxate) more commonly referred to as octinoxate is the most commonly used sunscreen and is allowed for use up to 10% in the EU and Australia and up to 7.5% in the US (20% in Japan). Octinoxate is an endocrine disruptor found to dysregulate hormonal homeostasis of the thyroid and also the reproductive system. Octinoxate exhibits anti-thyroid activity and is also anti-androgenic and anti-progestenic. Of little surprise, it also shows estrogenic properties.
Prenatal exposure to octinoxate induced adverse effects on the reproductive and neurological development of rat offspring. Over the course of 12 weeks, T4 levels in blood dropped and the activity of 5’-deiodinase, the enzyme responsible for converting T4 to T3 in the liver also dropped.
A review published in 2012 investigated the research around oxybenzone, octinoxate, homosolate, and a couple types of PABAs. PABA has been disallowed from use in sunscreens sold in Europe. It’s still allowed in America and Australia. Padimate O is a PABA derivative allowed in Europe, Japan, Australia, and America.
In animals, these UV filters were associated with reproductive or developmental toxicities and some of these sunscreens disturbed either or both the hypothalamic-pituitary-thyroid axis also known as HPT axis or the hypothalamic-pituitary-gonad system.
A couple of important notes here. While there’s abundant data for many of these UV filters, oftentimes the studies are performed by orally dosing lab animals and also at concentrations much higher than would be typical for humans to be exposed to even through ideal sunscreen use. That’s true for the thyroid effects reported here.
For some studies, the studies are conducted in vitro meaning out of the body or more commonly referred to as tested in a petri dish or test tube, and this is common for assessing a molecule’s ability to bind hormone receptors. Even though they’re not conducted in a living being, these studies still indicate that molecules are endocrine disrupting.
Now, if you remember last week’s conversation, I’m of the mind that everything we come into contact with on a daily basis is endocrine disrupting from the one on one with your boss to your daily tea ritual and yoga practice to the essential oil diffuser you turn on when you’re stressed, so I don’t believe that endocrine disrupting is the end all be all for assessing whether a compound is beneficial to your health or could be adversely impacting your health.
For this reason, I’d like to steer the conversation back over to what the FDA has found and what changes they’re proposing. We’ll also dive into some of the peer-reviewed scientific literature on these chemical sunscreens.
Which sunscreens is FDA reclassifying?
For the following chemical sunscreens, FDA believes there isn’t enough data in the public record to support classification as GRASE (generally regarded as safe and effective):
- Padimate O
FDA calls out the available literature on oxybenzone stating that some studies indicate absorption through the skin at a greater extent than previously understood and this can lead to significant systemic exposure including presence of oxybenzone in breast milk, amniotic fluid, and blood.
All 12 of the chemical sunscreens I just mentioned will be assigned to Category III, which means there’s insufficient data to permit a final classification as either Category I, which is GRASE or as Category II, non-GRASE.
This means that companies wishing to use these sunscreen chemicals will have to conduct studies to prove the active ingredient isn’t absorbed into your skin above the allowable limit and continue to demonstrate the SPF of marketed sunscreens, which was already a requirement and why sunscreens can list an SPF rating.
Their stated SPF rating is what makes sunscreens drugs, even if they are over-the-counter drugs. And, it’s also why the GRASE we’re talking about today has an “e” on the end because as a drug, the active ingredient those UV filtering chemicals themselves, have to demonstrate effectiveness.
There’s also GRAS without the “e” that is more general in the world of skincare and this is for ingredients that aren’t considered drugs in a product like preservatives, emulsifiers, and emollients.
For sprays, FDA is requiring additional data demonstrating adherence to particle sizes that avoid inhalation and also meeting flammability requirements. You can read more about the data or lack of data supporting the FDA’s decision by visiting the link in today’s shownotes.
Zinc oxide and titanium dioxide are still classified as GRASE under this new regulation. If you missed the episode on sunscreens vs. antioxidants, go back and give it a listen because I share why I’m not a huge fan of micronized zinc oxide and titanium dioxide in that episode, and yes, it has to do with the potential for migrating or absorbing into your skin along with their own ability to create free radicals despite being physical sunscreens.
Before we talk about the other reason why sunscreens are in the news this summer, I wanted to share some of the research supporting that these molecules really are a health concern.
What are the health effects of chemical sunscreens (beyond endocrine disrupting)?
We’ll start with oxybenzone.
Derivatives of benzophenone are pharmacologically active and bind with DNA.
The benzophenone moiety (moiety is the chemical structure of benzophenone and can be incorporated into a variety of molecules) itself is responsible for this DNA binding, and molecules containing the benzophenone moiety, like benzophenone sunscreens, are DNA photosensitizers. This seems like insanity to allow a known DNA binder as a sunscreen.
And, here’s why the sunscreen’s ability to penetrate your skin matters. If these sunscreens just sit on your skin’s surface, there’s no concern because they aren’t in contact with any living skin cells. However, based on the research that sunscreens can absorb deeply into your skin, deep enough to reach viable layers profuse with capillaries and cross your capillary’s epithelial layer and enter your bloodstream, the fact that benzophenone binds DNA is of profound concern.
Just a sidenote (because the fact that sunscreens can absorb into your skin really shouldn’t have been a big surprise)… in 2014, benzophenone was awarded the Contact Allergen of the Year status by the American Contact Dermatitis Society. Benzophenone is also associated with photosensitized DNA damage.
https://pubs.acs.org/doi/10.1021/ar300054e Benzophenone Photosensitized DNA Damage
Many of these chemical sunscreens only offer UVB protection, and while this may keep you from getting burned and help prevent some types of skin cancer, UVB protection alone really does nothing to help stop more sinister form of skin cancer, melanoma. To be clear, melanoma isn’t the only type of skin cancer that can kill you, and in fact, about 15,000 people die each year in the US due to squamous cell carcinoma, about twice as many deaths as melanoma.
There are three main types of skin cancer:
- Squamous-cell carcinoma
- Basal-cell carcinoma
There’s also a number of less common skin cancers including Merkel cell carcinoma, and we talked about Merkel cells in the very first episode. It’s worth mentioning this one because although rare, Merkel-cell carcinoma is very aggressive with lower survival rates even than melanoma, so early detection is especially crucial for this type.
Sunscreens are purported to protect from the incidence of skin cancer. And, while they protect against sunburn, solar keratosis, and non-malignant melanoma, the incidence of malignant melanoma among Americans quadrupled from 1975 to 2010. This same trend in increased incidence of MM holds true for the UK, where about a 5-fold increase was found between 1975 and 2010. For Denmark, incidence of MM increased from about 15,000 per 100,000. Now, it’s important to remember that correlation does not equal causation. One of my favorite podcasters, Melina Palmer, once interviewed a behavioral economist who gave this example. In the summer, sales of ice cream go up and so do the number of drownings. So, I could say ice cream causes drownings, but that’s ridiculous. Likewise, just because there’s an increased incidence of melanoma (and I imagine an increased use of sunscreen from 1975 to 2010), it’s equally ridiculous to say sunscreen causes melanoma without investigating to see if that’s really true.
If you Google “sunscreen melanoma” just those two words, nothing else, you’ll find authoritative sources on both sides of the argument. So, go to Google Scholar first and then search the words “sunscreen melanoma” to pull up actual research.
I just wanted to share results from a couple of reviews.
A study published in Journal of the American Board of Family Medicine in 2011 found that over the 30-year period between 1973 and 2003, incidence of melanoma increased at a rate of about 3% per year. A 2006 EPA publication stated (and I quote) “there is no evidence that sunscreens protect you from malignant melanoma.”
Several studies found that use of sunscreen either doesn’t significantly decrease the risk of melanoma or may increase the risk of melanoma. And a number of studies have also suggested that sunscreen users compared with non-users may be more prone to develop sunburns, and it’s been widely held that number of sunburns in your lifetime increases your risk of melanoma.
Another reason for this might be that both UVA and UVB contribute to the risk of melanoma, and many sunscreens, while excellent at blocking UVB, those superficial UV rays that cause sunburn, do little to block UVA rays, those more deeply penetrating rays that cause oxidative stress and free radical formation. And, UVB rays are the ones responsible for boosting your body’s own sunscreen… that antioxidant called melanin produced by melanocytes, the very cells impacted by melanoma.
Further compounding the question of whether sunscreens lower your risk for developing melanoma, there’s this… there’s little evidence that sun exposure is even associated with melanoma. You may be wondering what’s the evidence supporting that claim? The incidence of melanoma is higher for people living in northern states like Delaware, Vermont, and New Hampshire (incidence of more than 30 per 100,000) compared with folks living in Texas, Florida, Arizona, and New Mexico (<25 per 100,000). And, the incidence of melanoma in LA is 24.9 per 100,000.
Now, this isn’t definitive proof that there’s no effect of sun exposure on risk of developing melanoma, and Australia has the highest occurrence of melanoma of any country. The EPA estimates that the sun causes 65% of all melanomas. And, the other factor we haven’t even considered here is what type of sunscreen was being used in these studies.
Okay, so what are you supposed to do with this data? This is one girl’s thoughts… if you love sunscreen and can’t imagine walking outdoors without it,
- use a non-nano/non-micronized physical sunscreen with titanium dioxide and/or zinc oxide
- wear protective clothing. Both zinc oxide and titanium dioxide are broad spectrum, protecting from UVA and UVB rays though zinc oxide is better at blocking UVA rays
- always wear a hat
- remember to protect your ears and the back of your neck as these are common places for squamous-cell and basal-cell skin carcinomas
- avoid sunburn
- start using an antioxidant spray
Antioxidants work to soak up free radicals and other reactive oxygen species. And, unlike sunscreens, they’re supposed to soak into your skin. Antioxidants get depleted rapidly especially when you’re in the sun, so reapply about once an hour to keep your levels up. Rain Organica offers Marine Layer Antioxidant Mist with vitamin C and two types of peptides that are shown to protect your skin from the effects of UV rays, namely that oxidative stress and free radical energy.
Before we move away from this part of the conversation, quick question for you.
Why else are sunscreens in the news right now?
Sunscreens contaminated with benzene
In May of this year (2021), an independent lab released a press statement claiming that it found high levels of benzene, a known human carcinogen, in several sunscreens. They also issued a Citizen Petition to FDA to better define limits for benzene contamination in drugs and cosmetic products and also to recall the contaminated batches.
FDA already limits benzene to 2 ppm in drugs (which would include OTCs) and further states that benzene should not be used in the manufacture of any component of a drug product because of its unacceptable toxicity. Benzene can cause cancer, including leukemia and at high doses can cause dizziness, irregular heartbeat, and even death in extremely high concentrations.
Of the 78 products containing benzene at quantifiable levels (0.1 ppm or more), 14 had levels at or above 2 ppm, the FDA allowable limit.
Side note: Earlier in 2021 (in late March), Valisure issued a similar press release regarding benzene contamination in hand sanitizers and requested FDA action. FDA also has an interim limit of 2 ppm for benzene in aqueous based hand sanitizers, which was issued in March 2020 and updated in February 2021. I won’t dive into the hand sanitizer more in this episode other than to say, the big concern for both of these product types, sunscreens and hand sanitizers is… where’s the benzene coming from?
At this point, it’s unclear. Benzene is a common side product during the manufacturing process for some of these sunscreen ingredients. However, for drugs (including OTCs), all ingredients, both active ingredients, the UV filters themselves, and all inactive ingredients should be tested to ensure compliance with USP guidance, and this includes benzene testing for ingredients that may contain that compound.
And, every batch of drug finished products (including OTC drugs) are required to be tested before being released into the market. So… why wasn’t the benzene caught either during raw material CoA testing or during release testing for the finished product.
Most perplexing, why does a sunscreen containing only zinc oxide as the active ingredient contain benzene?
I was speculative at first thinking Valisure may just be trying to make a name for themselves, however, looking more closely at the company, which is a pharmacy that tests every lot it orders prior to receiving those lots and in turn selling them to patients and customers, I’m delighted over their business model, and it’s clear they’re looking out for the best interest of their customers.
Valisure is responsible for a number of Citizen Petitions to the FDA and was actually the company responsible for uncovering nitrosamine contaminants in a specific class of pharmaceutical drugs a few years ago. This seriously rattled the FDA and EMA, and both regulatory bodies introduced additional guidance for industry to both detect and prevent these compounds in finished products.
So, what’s the latest with the benzene contamination in sunscreens? Right now, it appears that only Johnson & Johnson has voluntarily recalled five Neutrogena and Aveeno sunscreen products due to contamination with benzene. You can find the complete list of sunscreens and lot numbers tested along with the concentration of benzene found in each on page 12 of Valisure’s Citizen Petition linked in today’s shownotes. You can also find the list of additional sunscreens tested that contained levels of benzene below 2 ppm on page 13 and 14 and also Attachment A of Valisure’s Citizen Petition linked in today’s shownotes.
Hopefully, we’ll understand why these products were so grossly contaminated with benzene in the coming months, and please know of the nearly 300 products tested, only one product containing more than 0.1 ppm benzene, which was the limit of quantitation for this analysis, contained only physical sunscreens. The remaining 33 OTC sunscreens in this greater than 0.1 ppm category contained one or more chemical sunscreens.
Chemical Sunscreens and Reef Safety
There’s one more piece of information on chemical sunscreens you may already know. In 2018, Hawaii passed a bill banning the sale and distribution of sunscreens containing oxybenzone and octinoxate due to the overwhelming number of studies showing these two chemicals wreak havoc on marine life and especially coral reefs. The island nation of Palau has adopted the world’s strictest national sunscreen standard banning all active sunscreen ingredients and preservatives known to be reef-toxic.
This list includes the UV filters oxybenzone, octinoxate, octrocrylene, & 4-methyl-benzylidene camphor. How toxic are these sunscreens to coral?
Coral exposed to seawater containing just 1 ppb octinoxate demonstrated complete bleaching after 14 days.
Because reef coral relies on photosynthesis, this is catastrophic. In the summer of 2015, water samples gathered within 30 yards of shore along the coast of Maui found levels of octinoxate in the water as high as 967 ppt, just 33 ppt below that 1 ppb level that completely bleached coral in 14 days.
I hope this has been informative and hopefully provided some clarity around what’s been going on in the world of sunscreens and why physical sunscreens are such a better choice compared with chemical sunscreens.
Would you be willing to share this episode with your friends and family? Please take a quick second to send them the link now.
http://haereticus-lab.org/octinoxate/ great article
https://undark.org/2019/06/12/science-sunscreen-public-trust-cancer/ excellent article “Wear Sunscreen” tongue in cheek
https://www.jabfm.org/content/24/6/735 Sunscreen and Melanoma: Is Our Prevention Message Correct?
https://www.sciencedirect.com/science/article/abs/pii/S0039128X1830014X Photoprotection of ultraviolet-B filters: Updated review of endocrine disrupting properties
https://ascopubs.org/doi/10.1200/JCO.2016.69.5874 Journal of Clinical Oncology Sunscreen Use in the Prevention of Melanoma: Common Sense Rules. Published online October 2016.
About the Author
Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding.
Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on.
Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.
You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.
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