Is Sunscreen Dangerous?

Every year at this time, I regularly field questions from my patients about sunscreen safety.  Much of this appears to stem from the Environmental Working Group’s annual report on sunscreens, in which they describe the “dangers” of using various sunscreen ingredients.  Their website is rife with graphic, red and orange hazard signs, as well as health warnings, features that may lead some of their visitors to the very mistaken conclusion that most sunscreens are somehow more dangerous than sun exposure.

There is an overwhelming scientific consensus that ultraviolet radiation (UVR) causes skin cancer. Over 90% of nonmelanoma skin cancers and 86% of melanomas are caused by UVR. 1,2 This is not a minor issue; in the US alone over 5 million cases of skin cancer are treated each year, at a cost of over 8 billion dollars. 3,4 More importantly, an estimated almost 10,000 Americans and 1150 Canadians will lose their life to melanoma this year. 5,6 Most experts would agree that skin cancer prevention is a public health imperative.

We now have high-quality scientific evidence that sunscreens prevent skin cancer. A large, randomized controlled trial was conducted in Australia over a 4.5-year period in order to examine this issue. At the conclusion of this study, participants who had been randomized to daily sunscreen use had developed 39% fewer squamous cell carcinomas than those who had been randomized to using sunscreen at their discretion. 7 Long-term follow-up of those who took part in this study over an additional 10 year period found that, participants in the daily sunscreen group had a 50% reduction in their risk of developing melanoma, and a 73% reduction in their risk of (the more dangerous) invasive melanoma. 8 We are in the midst of an epidemic of skin cancer, and sunscreen is one of the major means we have with which to temper it.

How Does the Environmental Working Group Evaluate Sunscreens?

The Environmental Working Group (EWG) uses a method of evaluating sunscreens that has never been published nor peer-reviewed.  They do not independently test sunscreens for their efficacy, but rather rank them based on their ingredients.  Up to 50% of the rating they give a sunscreen is based on a “hazard score” that they assign based on their interpretation of the scientific literature. This hazard score appears to give disproportionate weight to unpublished studies, and to research done in animals that does not reflect the way in which sunscreens are used in people. In many cases, their methodology leads the EWG to dissuade people from using products that provide excellent sun protection in the name of avoiding ingredients that they have deemed harmful.  

Let's Look at a Couple of the Sunscreen Ingredients the EWG Most Frequently Criticizes:


Oxybenzone is an organic (chemical) sunscreen ingredient (also known as a UV filter) that garners a "hazard score" of 8 on the EWG website, mainly because of its weakly estrogenic properties (it has properties that weakly mimic estrogen, the predominant female hormone). Their criticism is largely based on a 2001 study in which mice were fed massive quantities of oxybenzone, resulting in an enlargement of their uterii (plural for uterus). 9 It has since been calculated that it would take 277 years of typical, daily sunscreen use for human beings to achieve similar levels of oxybenzone exposure. 10 A study in which human volunteers applied generous quantities of a 10% oxybenzone solution (which is 67% more oxybenzone than the upper limit allowed in sunscreens by the FDA and Health Canada), found no significant alteration in hormone levels that could be attributed to oxybenzone exposure. 11

I would also like to address two studies that the EWG mentions on their website; one suggesting a link between oxybenzone and birth weight and the other suggesting a link to endometriosis. 12,13 It should first be said that neither of these studies was designed specifically to examine oxybenzone exposure - they were created to examine other variables, and the authors decided to add this variable much later. Because of this, neither study controlled for important factors (known as confounding variables), that would most certainly have influenced the results. For example, the study examining oxybenzone exposure and endometriosis did not control for the season in which the urine was analyzed. 13 Had more of the participants in the control group been sampled in the fall or winter, their levels of oxybenzone would have been lower by virtue of the fact that they were exposed to less sunscreen. The study on birth weight yielded conflicting results that make no sense from a biologic perspective. There are numerous other examples of such flaws that make the results of these studies highly suspect. Such studies, by virtue of their design, are unable to show that an exposure causes a particular health outcome. Stated differently, associations do not prove cause and effect and these studies can not be used to conclude that sunscreens are harmful.

Small amounts of oxybenzone are absorbed through the skin, and as such we should continue to study it to ensure that it does not cause harm.  However, despite its being widely used for over 25 years there is no scientific evidence that is of reasonable quality that shows that oxybenzone causes any disease in human beings (apart from uncommon cases of skin allergy).  For those who remain concerned, there are many alternatives available in drugstores and supermarkets.  A sunscreen’s active ingredients must be clearly listed on its label, making it simple to avoid oxybenzone if one chooses to do so.  

Retinyl Palmitate

Retinyl palmitate is a storage form of vitamin A that the EWG frequently cautions their readers about. It is not an active sunscreen ingredient (UV filter), but rather is an anti-oxidant that is added to sunscreens in small amounts because of its anti-aging benefits.  In the skin, vitamin A (an essential nutrient) is stored as retinyl palmitate, which is then converted into active vitamin A acid when the body needs it.  

The EWG's criticism of retinyl palmitate appears to largely stem from an unpublished study in which this chemical was applied to rats, following which the rats were exposed to ultraviolet radiation, and subsequently developed skin cancers at an accelerated rate. Dermatologists who reviewed this study correctly pointed out the various reasons why the study was both inconclusive and not generalizable, including the fact that the type of rats used are bred to be at high risk of developing skin cancer, even without exposure to radiation. 14 Providing support for the safety of this compound, a study published in 2009 found no evidence of photo-genotoxicity (damaging mutations in DNA in the presence of ultraviolet radiation) in hamster ovary cells that had been treated with retinyl palmitate. 15

Perhaps the most reassuring evidence regarding this compound comes from the tens of millions of people whose acne and psoriasis (among other conditions) has been treated with various topical vitamin A creams. Tellingly, there is not a single report in the literature of this treatment inducing skin cancer. In fact, oral vitamin A derivatives are used to prevent skin cancer in people who are at high-risk.

What Have Medical and Scientific Groups Concluded When Evaluating the Safety of Sunscreens?

The American Academy of Dermatology, the Canadian Dermatology Association, the Skin Cancer Foundation, and the EU's Scientific Committee for the Safety of Consumer Products have all reviewed the evidence regarding the safety of sunscreen ingredients in great detail, and have repeatedly concluded that they are safe. The Canadian Cancer Society has stated that they believe that oxybenzone and retinyl palmitate in sunscreens do not pose a cancer risk.  In fact, to the best of my knowledge, no major medical group or scientific body has ever made statements cautioning the public about the safety of today's sunscreens.  It is disheartening that, despite this, so many members of the media advance the fear-mongering headlines put out by the EWG in place of the evidence-based opinions of doctors and scientists.

Do you LIve Outside of the US? The EWG Sunscreen Rankings may not Apply to You...

International visitors to the EWG website may be especially shortchanged when they choose a sunscreen from among the list of those the EWG recommends.  There have been many exciting developments in the field of sunscreen technology over the past 15 years.  New sunscreen ingredients are now available in much of the world that can provide excellent, durable protection from the sun’s harmful rays.  Because most of these UV filters have yet to be approved by the FDA, they will not be found in products the EWG recommends.  International visitors who search the EWG website will not learn of sunscreens available to them that utilize these newer ingredients.

The sunscreen I use each morning demonstrates how effective modern sunscreen technology can be. While many of the products on the EWG's recommended list filter out approximately 80% of the ultraviolet A (UVA) rays that cause tanning (as well as skin cancer and sun damage), this sunscreen filters out 97.5%.17 That is the equivalent of using a product with an SPF of 38 instead of one with an SPF of 5 (except that SPF applies to protection from sunburn rather than specifically to UVA rays). To someone who treats skin cancer and sun damage every day that is a very significant difference.

In Summary

The Environmental Working Group is neither a governmental nor an academic scientific body.  It is an "envrionmental organization" that publicizes alarmist conclusions regarding numerous sunscreens, with little scientific evidence to support its claims.  What is needed instead is a balanced discussion of the risks and benefits of sunscreen use; one that reflects the importance of sun-protection and the known harms of ultraviolet radiation. We should continue to study and debate the safety of sunscreen ingredients, but the EWG should not mislead the public or the media when it comes to what we do, and do not know about their safety.  Animal studies that do not reflect real-life circumstances should not be presented as reasonable evidence that sunscreens are harmful. 

We know that excess sun exposure causes skin cancer and that sunscreens can help to prevent this.  The scientific evidence overwhelmingly supports the benefits of sunscreens in decreasing the risk of skin cancer and sun damage; benefits that far outweigh any unproven claims of health risks in humans.  Protect yourself and your family by using a "broad-spectrum" sunscreen with an SPF of 30 or higher. Apply the product you choose liberally, and reapply it frequently. Finally, remember that, while the focus of this post is on sunscreens, practicing sun safety should include such measures as seeking shade, avoiding sun exposure during peak hours, and using sun-protective clothing. If you protect your skin now, it will thank you for decades to come.


Dr. Michelle Levy has no financial ties to the sunscreen industry.  



1Koh HK, Geller AC, Miller DR, et al. Prevention and early detection strategies for melanoma and skin cancer. Archives of Dermatology 1996; 132: 436-442.

2Parkin DM, Mesher D, Sasiene P. Cancers attributable to solar (ultraviolet) radiation exposure in the UK in 2010. Br J Cancer 2011; 105: S66-9.

3Rogers HW, Weinstock MA, Feldman SR, Coldiron B. Incidence estimate of nonmelanoma skin cancer (keratinocyte carcinomas) in the United States Population. JAMA Dermatol 2015; Doi.101001 /jamadermatol.2015.1185 (Epub ahead of print)

4Guy GP, Machlin SR, Ekwueme DU, Yabroff KR. Prevalence and cost of skin cancer treatment in the US, 2002-2006 and 2007-2011. Am J Prev Med 2015; 48(2): 183-7.

5American Cancer Society. Cancer Facts & Figures 2015. Atlanta: American Cancer Society, 2015.

6Canadian Cancer Society. Canadian Cancer Statistics Publication. Toronto: Canadian Cancer Society, 2015.

7Green A, Williams GM, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal cell carcinomas and squamous cell carcinomas of the skin: a randomized controlled trial. Lancet 1999; 354: 723-9.

8Green A, Williams GM, et al. Reduced melanoma after regular sunscreen use: randomized trial follow-up. J Clin Oncol 2011; 29: 257-63.

9Schlumpf M, Schmid P, et al. Endocrine activity and developmental toxicity of cosmetic UV filters - an update. Toxicology 2004; 205: 113-22.

10Wang SQ, Burnett ME, Lim HW. Safety of oxybenzone: putting numbers into perspective. Arch Dermatol 2011; 147(7): 865-6.

11Janjua NR, Morgensen B, et al. Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate and 3-(4-methyl-benzylidene) camphor after whole body topical application and reproductive hormone levels in humans. J Invest Dermatol 2004; 123(1): 57-61.

12Wolff MS, Engel SM, Berkowitz GS, et al. Prenatal phenol and pthalate exposures and birth outcomes. Environ Health Perspect 2008; 116: 1092-1097.

13Kunisue T, Chen Z, Buck Louis GM, et al. Urinary concentrations of benzophenone-type UV filters in U.S. women and their association with endometriosis. Environ Sci Technol 2012; 46: 4624-4632.

14Wang SQ, Dusza SW, Lim HW. Safety of retinyl palmitate in sunscreens: a critical analysis. J Am Acad Dermatol 2010; 63: 903-6.

15Dufour EK, Whitwell J,et al. Retinyl palmitate is non-genotoxic in Chinese hamster ovary cells in the dark or after pre-irradiation or simultaneous irradiation with UV light. Mutation Research 2009; 672(1): 21-26.

16Weinstock MA, Bingham SF, DiGiovanna JJ, et al. Tretinoin and the prevention of keratinocyte carcinoma (basal and squamou cell carcinoma of the skin): a veterans affairs randomized chemoprevention trial. J Invest Dermatol 2012; 132: 1583-1590.

17BASF. BASF Sunscreen Simulator. Germany: BASF, 2015.

Michelle Levy

Dr. Michelle Levy is a board-certified dermatologist specializing in medical and aesthetic dermatology. A graduate of the University of Toronto's Faculty of Medicine, Dr. Levy provides a full spectrum of dermatologic services in Toronto, Canada. Education: M.D., University of Toronto, 1999 Residency in Dermatology, University of Toronto, 1999-2004 Employment History: Self-employed, North York, Ontario, 2005-Present Medcan. Consultant Dermatologist. 2007-Present