Why you should read the sunscreen label carefully

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Sunscreen is everywhere. It seems as if you can't set foot on a beach without being hit by a fine mist of aerosol sunscreen as it's sprayed by the concerned mother three towels down.

Yet, the rates of skin cancer in Canada have been on the rise for several years – a troubling fact, since melanoma and other forms of skin cancer can largely be prevented by avoiding ultraviolet rays.

How can this be? Part of the problem is our overreliance on sunscreen to do the heavy lifting when it comes to protecting us from the sun's harmful rays.

Canada's rules are fairly strict when it comes to sunscreen safety, according to several dermatology experts. Health Canada adopted new rules for sunscreen in 2013 to clarify what's allowed and crack down on potentially misleading claims. For instance, water-resistant sunscreens must state how long a person can swim or sweat before needing to reapply (the time varies between 40 minutes and 80 minutes, depending on the sunscreen). The rules also state that manufacturers can't use words that imply complete sun protection, such as sunblock, or imply that a product is waterproof, allows you to stay in the sun longer or reverses skin damage.

Health Canada has also taken some action on one particular chemical used in some sunscreens.

There are two basic categories of sunscreen: physical and chemical. Physical sunscreens, made with zinc oxide or titanium dioxide, sit on top of the skin where they reflect and absorb UV rays. Chemical sunscreens absorb UV rays.

In recent years, physical sunscreens have grown in popularity as warnings from certain advocacy groups mount about potentially risky ingredients in chemical sunscreen. For instance, the Environmental Working Group (EWG), a U.S.-based, non-profit advocacy group, warns against retinyl palmitate and oxybenzone, two common ingredients.

Retinyl palmitate, a form of vitamin A, is controversial because one study found it can cause skin cancer in mice.

However, many organizations and experts, including Dr. Sunil Kalia, assistant professor of dermatology at the University of British Columbia, argue the study had serious shortcomings and that concerns over retinyl palmitate are blown out of proportion.

For starters, the research was done on mice and the results don't necessarily translate to people. The American Academy of Dermatology says on its website there is no consistent evidence suggesting a health threat to people. Kalia also pointed out that vitamin A is used to treat skin cancer in some patients.

Sonya Lunder, senior analyst with the EWG, said in an interview that not enough is known about the extent of the risks posed by retinyl palmitate, but that even a small potential risk should be enough to warrant action. Since the EWG report first raised public concerns about the ingredient, it has been steadily falling out of favour with manufacturers, Lunder said.

While the scientific jury is still out, Health Canada has taken a pro-active approach and required a warning label on all sunscreens containing retinyl palmitate. They must warn consumers the ingredient may increase sun sensitivity and the possibility of sunburn. The warning must also advise consumers to "limit sun exposure while using this product and for a week afterwards."

Oxybenzone is also singled out by EWG as a hormone disruptor and allergen. One study in rats, for instance, found that oxybenzone increased their uterine size. Once again, most experts agree there is no need for individuals to be concerned. A 2011 analysis in the journal JAMA Dermatology looked at the levels of oxybenzone the rats were exposed to and how that would translate to humans. The authors found that people would have to cover 100 per cent of their bodies with sunscreen every day for up to 69 years, or 25 per cent of their bodies for 277 years, to get the same effect.

"It certainly has not been established in the scientific community that it causes any harm," said Dr. Michelle Levy, a dermatologist based in Toronto. "This is despite decades of use."

A number of experts, including Levy, say that groups such as EWG tend to exaggerate the harms of sunscreen ingredients even though the risk to humans is extremely small. Others have suggested a potential bias or conflict of interest, as the EWG has partnered with the makers of natural sunscreens on its sunscreen safety campaign, for instance.

Lunder disputed those claims and said the group's sunscreen report is not funded by the industry.

Most experts do agree, however, that Health Canada could be more strict is when it comes to UVA rays.

If you've picked up a bottle of sunscreen in recent years, you've probably come to know the term "broad spectrum." It means the product protects against both UVA and UVB rays. This is important because if you rely solely on a sunscreen with SPF, or the sun-protection factor, not broad spectrum coverage, you will only be protected from UVB rays. UVA rays penetrate deeper into the skin, causing damage and wrinkles. But new research has also found that it may contribute to the development of skin cancer.

However, knowing a sunscreen offers broad spectrum protection doesn't tell you how well it safeguards against harmful UVA rays. Health Canada's new rules to try to change that. Now, in order to carry the broad spectrum label, manufacturers must do a critical wavelength test, used to determine how well the product protects against UVA rays. Products must have a critical wavelength value of at least 370 nanometres to carry the broad spectrum label in Canada.

However, some experts argue that doesn't go far enough, considering that UVA wavelengths go beyond 370 nanometres. Under the current rules, there's no way for consumers to know if sunscreen protects them from UVA rays that go beyond 370 nanometres.

"That's a huge gap," UBC's Kalia said. "We don't know how much UVA protection there is and does it provide full protection?"

The bottom line is topical lotions and sprays can help protect you from the sun's damaging rays, but minimizing the risks involves much more than slathering on a layer of SPF 30 and hoping for the best.

Nearly 7,000 Canadians were diagnosed with melanoma – the most deadly form of skin cancer – in 2015, according to statistics from the Canadian Cancer Society. An estimated 1,150 died from the disease. Nearly 80,000 more were diagnosed with non-melanoma skin cancer, which can be successfully treated in many cases, but still lead to painful procedures and serious complications. Sunscreen has an important role to play, but it isn't the only answer.

Skin cancer is a serious and, in some cases, even a fatal diagnosis. Reducing the risk of developing skin cancer means limiting the time spent in the sun, particularly during peak midday hours and wearing protective clothing.