Skin cancer is the uncontrolled growth of abnormal skin cells, and it's the most prevalent form of all cancers in Canada.
"The good news is there are plenty of ways you can lower your risk of developing skin cancer," says Dr. Cheryl Peters, a senior scientist in cancer prevention at BC Cancer and BCCDC. "Unfortunately, there are quite a few misconceptions about sun protection that can confuse the issue."
Here are five popular myths about sun protection, along with some simple things you can do to keep your skin out of trouble.
You may have heard rumours that sunscreen can actually cause cancer or other health problems. In particular, some media has reported concern with ingredients oxybenzone, a synthetic estrogen, and retinyl palmitate, a form of vitamin A stored by the skin, and other stories might talk about vitamin D and risk of sunscreen reducing the amount of this important hormone in the body.
"This myth is very concerning to me," says Dr. Peters, "since there is no evidence that approved sunscreens cause cancer or other health problems. In fact, the opposite is true: not wearing sunscreen poses a significant cancer risk. For people who are concerned about their vitamin D levels, there are easy and much lower risk ways to keep levels up, including with simple dietary changes or taking a supplement."
Much of the concern about oxybenzone stems from a 2001 study with rats fed over 1,500mg of oxybenzone per kilogram per day.
"That amount is so much higher than we could ever be exposed to via normal use of sunscreen," says Dr. Peters. "This is not relevant for human health since the amount that's in sunscreen that's absorbed by the skin is tiny."
Some studies suggest that when exposed to UV radiation, retinyl palmitate generates free radicals — chemically reactive substances whose interactions with DNA may cause mutations leading to cancer. However, these studies have examined retinyl palmitate in isolation. In practice, when applied to the skin, antioxidants like vitamins C and E neutralize free radicals.
"A good way to check on the quality of your sunscreen is to look for endorsement from the Canadian Dermatology Association (CDA) on the bottle" says Dr. Peters. "However, if people have remaining concerns about these chemicals, they have other options. They are typically only contained in chemical sunscreens, or the fine mist and spray ones available. Physical sunscreens (the white creamy ones you might be familiar with) work differently, and do not contain these chemicals. Look for ingredients like zinc or titanium oxide on the label to identify these sunscreens."
Applying sunscreen may seem like a simple task: put it on your skin, rub and go. Yet we know that most people only apply about one-third to half of the amount that they need, leaving lots of skin exposed to dangerous UV radiation.
You need about one ounce of traditional (physical) cream sunscreen to cover your entire body. That's the equivalent of one full shot glass. To ensure you're covered, be systematic. Start from your forehead and work your way down over your torso, arms, hands and legs, all the way to the tips of your toes. Have a friend help you with hard-to-reach places, such as your back. For the best protection, reapply it after heavy sweating or swimming.
If you opt for a spray sunscreen, don't be stingy! Apply liberally and make sure you rub it in very well, and make sure to apply it out of the wind so it stays put on your skin instead of blowing away. It's also a good idea with spray sunscreens to wait 20 minutes before exposing your skin to the sun, as these sunscreens take a little bit of time to activate. The same consideration doesn't apply to the physical (white creamy) sunscreens, since they work right away.
Dr. Peters emphasizes the importance of fostering skin cancer prevention habits in children from a very young age. "Parents need to know that exposure to the sun is very important for children, with early life sunburns being very strong predictors of getting skin cancer later on," she says. "Just like teeth brushing, the earlier you start teaching your kids about sun safety, the better."
Since the advent of modern sunscreens, their efficacy has been measured by their Sun Protection Factor, or SPF, which measures protection against UV radiation. SPF is not a measure of the amount of protection, per se, but indicates how long it will take for UV to redden skin. For example, someone using SPF 20 will take 20 times longer to redden than without it. Always make sure to use sunscreens that state clearly on the bottle that they are "broad spectrum" (or that they protect against both UVA and UVB rays). Rumour has it that SPF 30 is the most you need; any higher is a marketing ploy.
This is a myth, says Dr. Peters.
"SPF 30 is a reasonable level of sun protection," she says. "But Sun Protection Factors are based on perfect use, and we know most people don't apply enough sunscreen."
To increase your confidence that you are protecting yourself with your chosen sunscreen, especially for people with fairer skin, choose a higher SPF, as long as you don't mind the texture of the product.
"The best sunscreen is one that you like to use, so you apply enough of it, and often."
Despite recent record-breaking sunny weather, if you live on the coast you're likely familiar with the month of "June-uary": that time of year coastal British Columbians sport jackets while the rest of Canada is beginning to bathe in sunshine.
"Many people think that you can judge your risk of UV exposure based on temperature, and that colder days mean you can skip the sunscreen," cautions Dr. Peters. "It is true that clouds offer some protection from UV radiation, but they're not perfect. The best way to know the level of risk is to check the UV Index – it's typically included in the apps you use to monitor the weather. When the UV Index is 3 or higher, you need sun protection, no matter the temperature outside."
And if you doubt the scientist, just ask any racoon-eyed spring skier bombing down Blackcomb or Big White.
According to Dr. Peters, cowboys had it right: wide brimmed hats are much better than other styles. Short brims, not so much — meaning that Canucks cap you've been donning daily may look cool, but it's not doing much to protect anything but your forehead from the sun. This leaves your neck and oft-forgotten ears at risk of sunburn and skin cancer.
A good general rule for hats: the brim should be at least the width of the palm of your hand, and cover the full circumference of your head.
"It is good to remember that sunscreen is a helpful tool, but it should really be your last line of defence against skin cancer when you can't avoid the sun by staying indoors or seeking shade," says Dr. Peters. "Staying out of the sun when the UV Index is 3 or higher is your best bet for skin cancer prevention. This is typically between 11 a.m. and 3 p.m. from April to October in most of Canada. However, as always, make sure to check your local forecast daily to better assess your risk!"
In other words, limit your risk of skin cancer by first limiting your exposure to the sun. Minimize the time you spend outdoors on sunny days, especially between 11 a.m. and 3 p.m. If you do go out, wear long sleeves and long pants with a tight weave, protect your eyes with UV-blocking sunglasses and invest in a wide-brimmed hat. And, last but not least, use a good layer of sunscreen that's SPF 30 or higher as your last line of defence between any exposed skin and harmful UV radiation.
