Confused about the mixed messages on sunscreen safety?
When a friend told Stacey Petersen that chemicals in her child’s sunscreen could be harmful, she wanted to find out more.
Petersen’s friend referred her to a report on sunscreen safety by the Environmental Working Group (EWG), a non-profit environmental advocacy organization that receives funding from many sources, including natural cosmetics companies. The report by the non-profit environmental advocacy organization is hugely popular, mentioned frequently in media articles.
It’s a frightening read. Petersen was alarmed to see, for example, that oxybenzone, a chemical in her own sunscreen “acts like estrogen in the body” and is “associated with endometriosis in women.”
“I was more concerned about my children, but if it’s disrupting hormones and it could be causing cancer, I don’t want to be exposed to that either,” says Petersen.
After some further research, however, she came across other research by dermatologists showing “that the amount [of oxybenzone] your body is absorbing is so miniscule that it’s not a problem.”
The fact that some environmental scientists say many sunscreens could be toxic while dermatoloigsts say they’re safe has led to a great deal of confusion.
“I have patients with fair skin who have sun damage tell me that they don’t use sunscreen because they think the chemicals cause cancer,” says Michelle Levy, a Toronto-based dermatologist who criticizes the EWG report for being inaccurate and fear-mongering. “That’s really not true…but the odds of you getting skin cancer as a result of not protecting yourself from the sun are really high.” (All of the dermatologists interviewed for this article stated that they do not receive funding from the sunscreen industry.)
So who’s right? Healthy Debate investigates.
Are sunscreen chemicals safe? Here’s what the evidence tells us
Active sunscreen ingredients are regulated as drugs in Canada, which means they undergo much more safety and effectiveness testing than cosmetics and other products. Health Canada scientists review the available clinical trials and safety information on a sunscreen ingredient that absorb or block UVA or UVB before approving it. The benefit of the ingredient must be shown to outweigh any potential adverse effects, such as allergic reactions, in human studies.
The chemicals that the EWG recommends most strongly against – oxybenzone and retinyl palmitate – have both been deemed safe by Health Canada and other scientific review committees. After reviewing dozens of studies on oxybenzone, the European Scientific Committee on Consumer Products concluded the chemical in the concentrations found in sunscreen “poses no health risk.” Another systematic review published in 2011 examined the available data on the effects of oxybenzone and retinyl palmitate and drew the same conclusion.
So why is the EWG so concerned? Let’s start with one of the main studies EWG based its oxybenzone concerns on. In this study, rats were fed repeated doses of the chemical, and as a result, the average size of their uteri grew by 23%. In other words, the chemical disrupted the hormonal activity of these rats.
There are two reasons why the study isn’t so alarming. The first is that the rats ingested incredibly high doses. “Toxicologists always talk about how it’s the dose that makes the poison so that’s important to keep in mind,” explains Levy. Another study – the one that gave Petersen a sigh of relief – showed that people would have to apply sunscreen with oxybenzone on a quarter of their body every single day for 277 years to reach the level of exposure that the rats received in the study.
The second is that rats are different from humans. Our skin is much more protective and our bodies process chemicals differently, explains Levy. As Healthy Debate has discussed before, chemicals that have major health effects in mice often don’t affect human health.
Because of chance, and because of their susceptibility, it’s easy to find the odd study showing a scary effect in mice or in cells for almost any chemical, explains Robert Nuttall, assistant director at the Canadian Cancer Society. For that reason, “we only become concerned when there is a lot of evidence and it’s all showing the same pattern,” he says.
In addition to the mice and petri dish studies, a handful of human studies raise concerns with oxybenzone. One study found women with higher oxybenzone concentrations had slightly higher rates of endometriosis, while another linked the chemical with lower birth weights in girls and higher birth weights in boys.
These studies don’t worry the dermatologists and cancer experts that recommend sunscreen because the studies only show correlations and they’re highly flawed. With the birth weight study, “it’s highly suspicious when [the same chemical is linked with] higher birth weights in boys and lower birth weights in girls,” says Dr. Jennifer Beecker, a dermatologist and the national chair of the Canadian Dermatology Association’s Sun Awareness Program. “There’s not a clear trend.” In other words, if the chemical truly affected birth weight, it would likely affect the weight of female and male infants in the same way.
Furthermore, birth weight can be affected by numerous other factors, including the mother’s body mass index, which wasn’t taken into account, explains Levy. Likewise, with the endometriosis study, there are many factors, including genetic ones, that contribute to endometriosis and the study didn’t rule out other potential causes, notes Jason Rivers, a Vancouver-based dermatologist.
In both studies, the levels of the chemical were measured only once in the women, not many times over a long period. Oxybenzone is processed and removed by the body, so a one-time measurement simply shows a person was recently exposed to oxybenzone, it doesn’t measure long-term exposure, explains Levy. And it’s only long-term exposure that relates to long-term medical effects.
In other words, the EWG based its recommendations against oxybenzone on a few flawed and inconclusive studies, rather than the overwhelming majority of studies that show these sunscreen chemicals to be safe.
The EWG’s claim that a form of vitamin A sometimes added to sunscreens – retinyl palmitate – is linked to an increase in skin cancer is also based on very weak evidence. The study behind that claim involved hairless mice that were “genetically modified to be susceptible to sun damage,” Nuttall points out. In fact, a control cream that contained what EWG itself deems a safe compound triggered skin cancers in those mice.
Levy adds vitamin A acid has long been used on the skin as a treatment for acne and the compound has been studied extensively in humans. She cautions that it’s important to look at the safety of chemicals in the doses they’re found in products, and in human studies, rather than studies in which very high doses are given to animals. “You can’t take one ingredient out of context,” she says.
Beecker calls the EWG report “dangerous.” Most of the sunscreens it recommends are expensive and only available to buy online. It’s worth mentioning that, in addition to receiving funding from natural beauty companies, the EWG profits from sales of the sunscreens that it recommends.
Beecker worries that the report may lead people to stop using sunscreen or use less sunscreen. “It dissuades the public from taking proper measures to prevent the world’s most common cancer,” says Beecker. Non-melanoma skin cancers are the most commonly diagnosed cancers, while one in 57 men and one in 74 women will develop melanoma, according to the Canadian Cancer Society.
Despite numerous attempts to schedule an interview with an EWG representative, no one was made available.
The growing recognition of the need for better UVA protection
In addition to the safety of sunscreen minerals and chemicals, the EWG report also looked at their effectiveness. Here’s where the health experts and the advocacy organization are more in agreement.
The EWG report criticizes many sunscreens for protecting against UVB but not protecting well enough against UVA. New studies suggest both are linked to skin cancers, including melanoma, but for a long time, it was thought that only UVB caused cancer, explains Beecker. “From what we now know, UVB is a little more important in causing cancer, but UVA also plays a role,” she says. UVA also plays a larger role than UVB in skin aging.
Since sunscreen protection factor, or SPF, only refers to how a sunscreen protects against UVB, it can be difficult to tell how well a sunscreen protects against UVA, but it’s getting easier.
Almost all sunscreens have some degree of UVA protection, but “the question is, ‘How good is the UVA protection?’” asks Rivers. In order to meet Health Canada’s “broad spectrum” label, sunscreens must contain ingredients that can protect against UVA rays up to at least 370 nanometers. But sunscreens vary in terms of how strongly they protect against these UVA rays.
The EWG report noted that it is more difficult to find sunscreens with high UVA protectors. Levy has written about what ingredients protect well against UVA.
The take home message
Research shows that, when applied properly and frequently, sunscreens help prevent melanoma and also squamous cell carcinoma. That said, there is also evidence that shows sunscreens give people a false sense of security, causing them to stay out in the sun longer than they should, which could leave them no better off from a skin cancer risk standpoint.
For this reason, Nuttall stresses sun protection measures like seeking shade and limiting one’s time in the sun, especially during the mid-day hours. “There’s no question that UV radiation causes skin cancer, both melanoma and non-melanoma,” says Nuttall. “Sunscreens are an important tool in protecting Canadians from skin cancer, but they’re not the only tool.”
Sunscreens don’t stop all of the sun’s damaging radiation; instead they prevent a percentage of the damaging rays from penetrating the skin. An SPF of 30 means that it would take you 30 times longer than if you weren’t wearing sunscreen to get burned. But studies show we don’t apply sunscreen thickly enough, meaning we only get a quarter to half of the protection promised on the bottle. Thus, an SPF 30 sunscreen becomes an SPF 15 or even 10 because most people don’t put on enough of it, Beecker points out.
Beyond looking for sunscreen with good UVA as well as UVB protection, there’s no evidence to show that you have to worry about the ingredients in your sunscreen. Still, the Environmental Working Group gets attention by arguing that dozens of sunscreen chemicals could be dangerous, linked to everything from cancers to reproductive toxicity.
For the average reader who sees those words associated with a sunscreen ingredient, “it’s really not clear in the report that that’s in fish and that it’s at astronomical levels,” says Levy. “People are being frightened from using sunscreen, which is disconcerting when you see skin cancer all day.”