Jul 9, 2018 · 17 min read

Hormone Disruption from Bioaccumulative Chemical Sunscreens, or How I Learned to Stop Worrying and Love the Zinc Oxide

Over 97% of participants tested positive for the chemical oxybenzone in their urine in a 2008 CDC study.

What the hell is oxybenzone and why is it in your body? Oxybenzone is the most widely used chemical for UV filters that you’ve never heard of. But wait there’s more than just this persistent body burden going on here. Oxybenzone has been associated with significant hormone disruption in animal studies, smaller birthweight in human babies, and its known bioaccumulative effects are now being banned for environmental destruction. Yet it is still found in over 60% of sunscreens on the market. This chemical is being banned for fish, but hey you can still use it. Should you? This the question I began asking myself this year.

Big Sur Marathon 2014

BACKGROUND — My story begins in the beautiful sun-drenched state of California where I grew up 7 miles from the beach. The weather is so balmy and nice that it’s easy to spend every season outdoors. I’m a marathon runner, a water polo player and swimmer, beach bum, and a lover of hiking in high altitudes. As a California native I’ve dutifully slathered on the highest SPF I could find for years, worn hats, sunglasses and shunned roasting myself poolside for vanity. I would rather spend my skin cells on adventures outdoors and the orange leather look never jived with my punk sensibilities. I’m also a classical archaeology major, trained in Italy. I spent 10 hour days in the blazing Sicilian sun doing backbreaking labor in large open trenches. Sunscreen was not optional and we all slathered it on multiple times a day. I’ve followed the sage advice of that nineties Baz Luhrmann song “Everybody’s Free to Wear Sunscreen.” But it’s never done any harm to me, right?

Well actually now I’m not so sure. I began researching the ingredients in sunscreen when I was pregnant last year. I couldn’t find a lot solid information, just recommendations on random blogs. I was so overwhelmed keeping track of all the other things I wasn’t or was supposed to be doing that sunscreen fell by the wayside and I continued to use the products that I had always used. I use the lotion sunscreen because I never miss a spot like I do with the spray stuff. I wear Aveeno moisturizer with SPF 30 every single day. I like SPF 50 Coppertone Water Babies Pure and Simple and Neutrogena Sport Face for my face for long runs, marathons and surfing. Whenever I’m getting geared up for a run I put on my Sport Face and feel just a little bit more motivated, just saying I got on my Sport Face! My husband prefers SPF 70 Neutrogena Sun Defense in the spray can for its ease of application and uses whatever face sunscreen I have on hand. We also keep travel size bottles of random types/brands stashed here and there, in the glove compartment, in the Camel Bak, etc. for hikes and unexpected reapplication.

Then I had my son and I became a bit more aware coming out of the fog of the newborn stage that he needed to wear sunscreen too but I didn’t know what to choose. Were the products we already had safe? I mean Coppertone Water Babies is for babies, it says so right on the label. Then I read that no sunscreen is actually recommended for babies younger than 6 months, as they should be protected from the sun with protective clothing, shade, and avoidance strategies. Even further, babies older than six months, children and pregnant women should wear mineral sunscreens only. Why I had I never heard this before? Why wasn’t this on the label? What is actually in my sunscreen?

TECHNICAL INFORMATION — So I started reading. Commercial sunscreen is divided into three categories of UV filter types; chemical, mineral and combined chemical and mineral preparations. The first are the most familiar products which usually contain some combination of avobenzone, oxybenzone, homosalate, octisalate, and octocrylene. These organic chemical absorbers are also called benzophenone compounds. Chemical sunscreens are combinations of these chemicals because they work most effectively when paired together as each one has inherent weaknesses and instabilities. These chemicals work by absorbing the UV radiation through chemical reactions (Gilbert, et al, 2012). The second group of products are often referred to as mineral sunscreens because they contain metal oxides like zinc oxide and titanium dioxide. These are often referred to in scientific literature as inorganic chemicals. Mineral sunscreens work by reflecting UV radiation based on Rayleigh scattering and also a smaller portion of absorption. The third type combines both organic and inorganic filters for wider spectrum protection. This type can prove troublesome because I’ve actually purchased sunscreen that said zinc in big fat letters on the front only to find that it also contained chemical UV filters.

Perfect! This is exactly what I was looking for….
Are you kidding me??????

ROUTES OF EXPOSURE — to the UV filters in sunscreen are transdermal, inhalation, and inadvertent ingestion, with this last exposure method evidenced most often in children. (Maipas & Nicolopoulou-Stamati, 2015). Inhalation risk is increasing with the more widespread use of spray-on sunscreens. Additionally, chemical UV filters are absorbed in the bloodstream whereas inorganic UV filters sit on the surface of the skin and are not absorbed, except in nanoparticle formulations and this is highly dependent on particle size and still debated with ongoing research as studies have resulted in different findings. Further, persistent chemicals like oxybenzone have been found to remain in the water after bathing and swimming, and even in wastewater far from the source of contamination so water contamination is likely also an exposure risk although this is not documented in any of the sources I read.

Here are the chemical profiles for the products I have in my bathroom cabinet. I’ve changed my game up a bit and have highlighted my new products in italics and my traditional products are left plain. Oxybenzone is identified in red because it poses the most significant risks to human health and is nearly ubiquitous in chemical sunscreens.

As you can see every sunscreen I was using before contained chemical UV filters. Each of these products are a veritable cocktail of chemicals, which have their own risks and impacts to human health. Chemical sunscreens are always combined in consumer products because no chemical sunscreen is either stable or effective alone. As you can see in the table above each chemical preparation included several types of UV filters. So to say that any chemical alone has not shown negative effects is nearly pointless as it is always paired with another chemical sunscreen, most often avobenzone or oxybenzone. I found little evidence of analysis on the synergistic effects of these chemicals despite the fact that they are always used together.

BREAKDOWN OF EACH CHEMICAL RISK — Sunscreen absorption is the most common exposure risk and it occurs in the intended application of the product. he break down of the product on the skin through chemical reactions can also produce adverse effects. Photostability is the ability of the UV filter to absorb and deflect the energy of radiation from the skin. This involves a complex chemical process and heat transfer. The full implications of this reaction on human health is debated among scientists. The degradation of photostability, thus the failure of the UV filter to adequately absorb and deflect radiation from the skin occurs for the following reasons “isomerization, fragmentation, reaction to other molecules or production of free radicals” (Nash & Tanner, 2014). The risks involved with photoinstability may include photoirritation, phototoxicity, and photoallergic reactions and would also include increased exposure to UV radiation as the UV filter failed.

Endocrine disruptors are coming under increased scrutiny as the ubiquitous use of chemicals in personal care products has existed long enough to show long term changes and patterns. The most significant effects of endocrine disruption are seen in reproductive health systems as cancers, infertility, and measurable hormonal changes. Several chemicals used in sunscreen have known endocrine disrupting effects.

OXYBENZONE is one of the most widely used chemicals in sunscreen and coming under intense scrutiny and regulation in recent years. EWG classifies this UV filter with the highest hazard score of all the sunscreens rated (8/10). This is the chemical that is deemed unsafe for reefs and marine life and is being banned in international markets, Hawaii is the first state in the US to ban this chemical (Glause, 2008). Oxybenzone has a persistent body burden. It has been detected in nearly all people tested, found in human plasma, urine and breast milk. Oxybenzone has shown several hormone disrupting effects such as estrogenic, anti-androgenic effects, and is associated with birth weight changes in human babies. Oxybenzone has also reported the highest allergic and photoallergic reactions. Animal studies have shown even more significant effects such as lowered sperm density and changes in oestrus cycle length, however critics say these are not in line with actual human doses (Maipas & Nicolopoulou-Stamati, 2015, Gilbert et al, 2015).

OCTINOXATE aka OCTYL METHOXYCINNAMATE is considered a cinnamate based chemical has exhibited impairments in hormone release in animal studies, which may impact normal function of the pituitary and thyroid glands. In animal studies of rats delayed sexual maturation, central nervous system toxicity and additional organ toxicities were also found Octyl methoxycinnamate can penetrate the stratum corneum and enter the bloodstream in humans. This chemical is also banned for use in Hawaii, as it is not reef safe.

OCTOCRYLENE is also reported as one of the most photoallergic and allergic responses along with Oxybenzone and although not studied thus far it is similar in structure to other chemical UV filters and likely penetrate the stratum corneum. (Maipas & Nicolopoulou-Stamati, 2015, EWG 2018).

HOMOSALATE & OCTISALATE — homosalate and octisalate are salicylate compounds and have the lowest reported incidence of photoallergic and allergic skin reactions and limited evidence of endocrine disruption according to some sources, although others report that it does, showing anti-oestrogenic, androgenic and anti-androgenic activity too.

AVOBENZONE has been quite popular in recent formulations as it provides excellent sun protection and no evidence of hormone disruption, however it is unstable in sunlight, yeah you read that correctly, so it must be paired with other chemicals to stabilize it and when the product breaks down it may cause allergic reactions. (EWG Sunscreen Guide, 2018).

TITANIUM DIOXIDE and ZINC OXIDE are inorganic mineral sunscreens and extremely effective UV filters. According to EWG there is no known endocrine disruption caused by these minerals, however two peer reviewed studies, Maipas & Nicolopoulou-Stamati, 2015 and Smijs & Pavel, 2011, have found that nanoparticulate formulations cause reproductive toxicity in rats, mice, fish and earthworms.

RISKS OF NANOPARTICLES — Although I’ve begun to use mineral sunscreens I’m now aware that nanoparticulate minerals are widely used in the formulation of these products. Nanotechnology manipulates matter at the nanometer scale. Nanoparticles are used in the preparations of mineral sunscreens to avoid the gritty feel and white cast of traditional products but it is a relatively new technology, “toxicity concern about nanoparticles in sunscreens is due to their small size, their ability to evade immunologic defence mechanisms, to form complexes with protein” (Gilbert, et al, 2012). The small size of nanoparticles increases their reactive surface area which directly impacts their particle toxicity and their small size also enhances their ability to be absorbed into deeper layers of the skin.

Example of NO-NANO labeling on mineral sunscreen

The use of nanoparticles is an emerging science and it’s not limited to sunscreens and personal care products. The use of nanoparticles is most often not labeled. I’ve even discovered through this research that my favorite mineral based makeup uses nanoparticles and now I’m switching to a new product with some trepidation. There are significant adverse health risks associated with these formulations. Surprisingly not being broadcast as loudly is that titanium dioxide nanoparticles are also not reef safe, as the reef can ingest the small sized particles (Glause, 2018).

Due the widespread use and relatively little study on nanoparticles I think more research is required to ensure their safety in consumer products, particularly the risks associated with aerosolized or powdered forms. It is difficult to identify whether or not a product formulation uses nanoparticles since labeling is not required. Calling the product information line or purchasing products that do label which of their products contain nanoparticles, like Badger, are the best ways to be informed consumers.

BODY BURDEN — So now that I’m woke and using mineral sunscreens I’m safe right? Well not so fast. I can’t even recall all of the sunscreens I used as a kid, Bullfrog, Coppertone, Hawaiian Tropic, NO AD, ad nauseum. Although it’s really great I’m changing my ways and preventing further exposure to chemical sunscreens, the persistent body burden of oxybenzone means that it’s already in my system. As the 2008 CDC report discovered 97% of those tested had oxybenzone present in their urine, the levels were higher for women and girls than for men and boys. Organizations are seeking a safety regulations for this chemical but due to industry push-back no rulings have been made. Additionally because chemicals like oxybenzone hang around in the water long after the bathers have left, it means that I will continue to be exposed to these chemicals when I’m swimming with people who use them. Like second-hand smoke I will share some of the exposure even though I’m making different choices for myself.

DOES HIGH SPF EVEN MATTER? — Sun Protection Factor (SPF) is the rating system used to identify the levels of protection a UV filter offers against UVA only. SPF 15 as a multiplicative factor of the body is 15 times stronger than the natural defenses of your skin alone. SPF has diminishing returns so 30 is not twice as strong as 15. The increases in protection are like an asymptote, the increased benefit becomes smaller and smaller as the SPF number increases but never quite hitting a risk of zero. Like a mile per gallon rating on a vehicle, your mileage with SPF may very. Lab conditions to mimic sunlight exposure are difficult to correctly calibrate and users may use more or less than the prescribed amount. Procter & Gamble, the personal care product giant, is fighting to cap all SPF ratings at 50, citing evidence that lab testing of competitor products rated at 100 SPF vacillated widely between SPF ratings of 35 to 75 across 5 different laboratories, but nowhere near close to the 100 SPF on the label. (Badger.com, 2018).

Even more interesting from a consumer point of view is that higher numbers of SPF aren’t always better for our health. I assumed that more is better and used the highest SPF products I could find, with many of my products topping out at 70+ SPF. Even now my facial mineral sunscreen is SPF 50 but many studies show that higher SPF sunscreens contain a higher concentration of active ingredients in order to provide such numbers. This increases the amount of exposure and therefore increases the risks of negative health impacts. So don’t go crazy on the SPF ratings. Something between SPF 30–50 is the most effective range, and apply a sufficient amount to coat the skin and reapply as directed. All sunscreens degrade over time and need to be reapplied every few hours in the sun, regardless of SPF rating or chemical or mineral composition.


“The Food and Drug Administration has failed miserably in its duty to protect the public from toxic chemicals like oxybenzone in personal care products. At the request of industry lobbyists, including Supreme Court Chief Justice John Roberts, who represented the Cosmetic Toiletry and Fragrance Association, the agency has delayed final sunscreen safety standards for nearly 30 years. FDA issued a new draft of the standards last October under pressure from EWG, but continues to delay finalizing them at the behest of the regulated industry.” — Environmental Working Group

The more I discover about weak consumer regulations in the US, the more I feel like this statement is just an adlib, and I could just insert into this statement any dangerous chemical, any industry and any federal agency and it would actually be true. When is the welfare of the American people going to come before the economic profit of a corporation or industry? When will the regulatory bodies built for the purpose of protecting us actually start to do so? In such a capitalist system we must become informed consumers and fight back with our dollars. The only thing we can do is to contact our representatives, purchase products from corporations that adhere to higher standards and provide transparency in their labeling, and check international regulations as EU are often higher and products with these ratings are often easy to find. We must protect ourselves because no regulatory body is really acting in our best interest.

CAVEAT EMPTOR — I don’t foresee any comprehensive action by the Food and Drug Administration (FDA) to regulate or identify the risks of sunscreen use. In light of changing international regulations for reef-safe products I hope that oxybenzone based sunscreen will be phased out entirely. This regulation will not prevent companies from using regrettable substitutions so consumers should remain vigilant about the preparation of their sunscreen. Due to the anti-regulatory posture in the US consumers must protect themselves from the hidden dangers of sunscreens, namely the hormone damaging effects and the persistent body burden. The most at-risk populations for the product class of chemical sunscreens are pregnant women and children, and women considering pregnancy should likely consider this guidance as well. The relatively unstudied risks of nanoparticulate absorption, inhalation and ingestion are risks for everyone. The majority of studies on the risks of inhalation toxicity have been from occupational studies which include mostly men, so men should not consider themselves exempt from these risks.

WHAT SHOULD YOU USE? — As with any risk in our environment the best thing you can do to be a healthy and sun-safe consumer is to limit your exposure. This doesn’t mean never go outside or just use 2 gallons of mineral sunscreen and call it good. Think critically about your activities outdoors and use a multifactor approach to sun-safety. Avoid activities in the noon-day sun, wear wide brimmed hats and protective clothing when outdoors. Active brands now offer several products with ratings of Ultraviolet Protective Factor (UPF). UPF clothing blocks both UVA and UVB rays. A rating of 50+ is ideal and REI has a handy article for help selecting these products here. Children should wear UPF rated rash guards with their bathing suits to limit sun exposure and also limit the amount of sunscreen necessary. Even Target and Old Navy sell cute and affordable options for rash guards now. Rash guard is a strange name but it’s a garment that was developed for surfers to prevent rash and chafing from repeated contact with sand and the surfboard.

Ditch the chemical sunscreens in favor of mineral based sunscreens from reputable brands like Badger and Thinksport. From an economic standpoint there is a negligible difference in price between name brand chemical and mineral preparations, although fewer generic store brand mineral products exist at this time. SPF ratings between 30–50 are sufficient. If you are reapplying several times per day consider other mitigation strategies. Cream or lotion preparations are preferred as the minerals are applied in a stable solution whereas the spray on formulations aerosolize micronized particles which can travel deep into the lungs. Just avoid spray on products, the complete risks of inhalation toxicity are unknown due to lack of study, but preliminary findings are alarming and prudent avoidance is advised. The cans aren’t easily recycled either. To view a comprehensive list of safe sunscreen products checkout the Environmental Working Group’s 2018 Guide to Sunscreen and you can even see how your current products stack up to the competition. Remember to research your products and fight with your dollars, only you have your best interests in mind.

FINAL THOUGHTS — Through this research I’ve found a few key takeaways; sunscreen poses a significant endocrine risk, despite widespread sunscreen use incidence of malignant melanoma is steadily increasing (Bora et al, Krause et al) and SPF 15 is actually pretty good.

So I’m not sure if I need sunscreen as much I thought I did. When I’m taking my kid out for a walk around the neighborhood now I just put on a hat and sunglasses and make sure the top of the stroller is up. I’m no longer reaching for the spray bottle of SPF 50 every time I go outside. Sure if we’re headed down to Ladybird Lake or Deep Eddy I’m packing the Alba mineral sunscreen but I’m also sitting in the shade and wearing a hat. I’m still on the fence about using nanoparticles in my sunscreen. I can’t find a decent daily moisturizer with a non-nano mineral formulation so I’m left weighing the risks between nanoparticles and lesser toxic chemical sunscreens like avobenzone and homosalate. I’m switching to Badger for most of my regular sunscreen needs and I will keep checking the EWG sunscreen report every spring. I’m not going to stop living my life or stay inside. I’m just going to use less sunscreen in general and make sure what I am using is safe. I’m unsure what to do with the pile of half used sunscreen in my bathroom but I’m going check first to see if it’s safe to put in the regular trash….


Bora, N. S., Mazumder, B., & Chattopadhyay, P. (2018). Prospects of topical protection from ultraviolet radiation exposure: a critical review on the juxtaposition of the benefits and risks involved with the use of chemoprotective agents. The Journal of Dermatological Treatment, 29(3), 256–268. https://doi.org/10.1080/09546634.2017.1364691

CDC: Americans Carry Body Burden of Toxic Sunscreen Chemical. (n.d.). Retrieved June 27, 2018, from https://www.ewg.org/research/cdc-americans-carry-body-burden-toxic-sunscreen-chemical

Day, L. (2014). Vitamin D and sunlight. Early Years Educator, 16(4), 16–18. https://doi.org/10.12968/eyed.2014.16.4.16

Dunford, R., Salinaro, A., Cai, L., Serpone, N., Horikoshi, S., Hidaka, H., & Knowland, J. (n.d.). Chemical oxidation and DNA damage catalysed by inorganic sunscreen ingredients. FEBS Letters, 418(1–2), 87–90. https://doi.org/10.1016/S0014-5793(97)01356-2

Gilbert, E., Pirot, F., Bertholle, V., Roussel, L., Falson, F., & Padois, K. (n.d.). Commonly used UV filter toxicity on biological functions: review of last decade studies. International Journal of Cosmetic Science, 35(3), 208–219. https://doi.org/10.1111/ics.12030

Glusac, E. (2018, May 3). Hawaii Passes Bill Banning Sunscreen That Can Harm Coral Reefs. The New York Times. Retrieved from https://www.nytimes.com/2018/05/03/travel/hawaii-sunscreen-ban.html

Kostyuk, V., Potapovich, A., Albuhaydar, A. R., Mayer, W., De Luca, C., & Korkina, L. (2017). Natural Substances for Prevention of Skin Photoaging: Screening Systems in the Development of Sunscreen and Rejuvenation Cosmetics. Rejuvenation Research, 21(2), 91–101. https://doi.org/10.1089/rej.2017.1931

Krause, M., Klit, A., Jensen, M. B., Søeborg, T., Frederiksen, H., Schlumpf, M., … Drzewiecki, K. T. (n.d.). Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV-filters. International Journal of Andrology, 35(3), 424–436. https://doi.org/10.1111/j.1365-2605.2012.01280.x

Lademann, J., Weigmann, H.-J., Rickmeyer, C., Barthelmes, H., Schaefer, H., Mueller, G., & Sterry, W. (1999). Penetration of Titanium Dioxide Microparticles in a Sunscreen Formulation into the Horny Layer and the Follicular Orifice. Skin Pharmacology and Physiology, 12(5), 247–256. https://doi.org/10.1159/000066249

Lodén, M., Beitner, H., Gonzalez, H., Edström, D. W., Åkerström, U., Austad, J., … Wulf, H. C. (n.d.). Sunscreen use: controversies, challenges and regulatory aspects. British Journal of Dermatology, 165(2), 255–262. https://doi.org/10.1111/j.1365-2133.2011.10298.x

Maipas, S., & Nicolopoulou-Stamati, P. (2015). Sun lotion chemicals as endocrine disruptors. Hormones (Athens, Greece), 14(1), 32–46.

Montenegro, Lucia, Turnaturi, R., Parenti, C., & Pasquinucci, L. (2018). In Vitro Evaluation of Sunscreen Safety: Effects of the Vehicle and Repeated Applications on Skin Permeation from Topical Formulations. Pharmaceutics, 10(1), 27. https://doi.org/10.3390/pharmaceutics10010027

Nash, J. (2006). Human Safety and Efficacy of Ultraviolet Filters and Sunscreen Products. Dermatologic Clinics, 24(1), 35–51. https://doi.org/10.1016/j.det.2005.09.006

Nash, J. F., & Tanner, P. R. (2014). Relevance of UV filter/sunscreen product photostability to human safety. Photodermatology, Photoimmunology & Photomedicine, 30(2–3), 88–95. https://doi.org/10.1111/phpp.12113

Smijs, T. G., & Pavel, S. (2011). Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness. Nanotechnology, Science and Applications, 4, 95–112. https://doi.org/10.2147/NSA.S19419

Sunscreens, E. 2018 G. to. (n.d.). EWG’s 2018 Guide to Safer Sunscreens. Retrieved June 27, 2018, from https://www.ewg.org/sunscreen/report/executive-summary/

What Is SPF Sunscreen? — Sun Protection Factor explained by Badger. (n.d.). Retrieved July 9, 2018, from https://www.badgerbalm.com/s-30-what-is-spf-sunscreen-sun-protection-factor.aspx


Written by


Treeusable 2018

Healthy products for healthy people and planet

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade