‘SPF 30 Is All You Need,’ Plus 8 More Sunscreen Myths Debunked

To keep your skin healthy and safe this summer, read this first.
By Raina Delisle

Summer dress season is in full swing, and with the freedom of scoop necks and spaghetti straps comes the stress of selecting a sunscreen. What SPF is necessary? Do children need a special formula? And are chemical ingredients really dangerous? There are lots of rumours about sunscreen floating around online and on the beach, adding to the confusion. With skin cancer on the rise in Canada, it’s more important than ever to separate fact from fiction. We asked dermatologists to debunk the most dangerous, deceptive and downright silly myths.

Myth: There’s no added value to wearing anything above SPF 30

The Canadian Dermatology Association (CDA) recommends using a sunscreen with a minimum SPF of 30, but going higher can add an extra layer of protection. SPF, which stands for sun protection factor, is a measure of how long you can spend in the sun before burning. Wearing a sunscreen with SPF 30 allows you to be outside 30 times longer without getting a sunburn. That means that someone who burns in 20 minutes without protection would be able to spend 600 minutes, or 10 hours, in the sun before turning red.

If you put on sunscreen perfectly—applying a generous layer to all exposed areas of the body—SPF 30 should be adequate, says Jennifer Beecker, a dermatologist and research director in the Division of Dermatology at The Ottawa Hospital. However, research shows that people apply a quarter to half the recommended amount, which reduces the SPF. “We find that when patients put on a higher SPF, it can counteract the under-application effect,” says Beecker, who is also national chair of the CDA Sun Awareness Working Group.


Several studies back this up, including one published in 2017 in the Journal of the American Academy of Dermatology. In that study, people wore SPF 100+ sunscreen on one side of their face and SPF 50+ on the other, and the researchers found that SPF 100+ was significantly more effective in preventing sunburn.

Myth: Sunscreen can be waterproof

“There is no sunscreen that is truly waterproof,” says dermatologist Mark Lupin, director and founder of Cosmedica Laser Centre in Victoria. The best you can get is water-resistant for up to two hours, after which it needs to be reapplied. Health Canada prohibits companies from labelling their products as “waterproof” or “sweat-proof,” and suggesting that sunscreen can be reapplied to wet skin, but bottles emblazoned with these misleading claims are still on store shelves. Make sure you check how long your sunscreen holds up in the water and towel off before thoroughly reapplying it. It’s also important to let it set for 15 minutes so it doesn’t wash off when you jump in the water.

Myth: Wearing sunscreen is all you need to do to protect yourself from the sun

Lathering up is not a licence to lie by the pool all weekend. Too much sun, with or without sunscreen, can damage the skin, leading to premature aging and skin cancer. Dermatologists recommend wearing sunglasses, a hat and protective clothing, as well as seeking shade and minimizing outdoor time during the intense midday hours of 11 a.m. to 3 p.m. “Sunscreen is meant to protect you when you can’t do anything else to protect yourself,” Beecker says. “It’s not enough on its own.”

Lupin adds that it’s important to choose a broad-spectrum sunscreen that protects against UVB and UVA radiation. “All sunscreens filter the UVB rays (think B for burn), but not all sunscreens are good at protecting against UVA rays (A for aging). Now we also know infrared light, which very few sunscreens can screen for, can also damage the skin.”

However, there is excellent evidence that sunscreen prevents cancer. Studies based on a landmark randomized controlled trial in Australia found that daily use of an SPF 15+ sunscreen reduced the rate of squamous cell carcinomas by 68 percent over the 4.5-year trial period and 40 percent eight years later, and cut the risk of melanoma in half 10 years after the trial. “I can’t think of any other intervention in the world that decreases a cancer more,” Beecker says. “It’s stunningly effective.”


Myth: The chemicals in sunscreens are harmful to humans

Concern has been growing about the safety of the chemicals in sunscreens, leading to the proliferation of natural products. Chemicals can cause allergic reactions and some studies show they interact with human sex and thyroid hormones, though no risk to humans has been proven. “There’s a lot going around about this theoretical risk, yet we know that sunscreen is a very powerful protector from skin cancer,” says Beecker.

According to the Environmental Working Group, which monitors the safety of sunscreens, the most concerning chemical is oxybenzone. A study showing an estrogenic effect in rats raised considerable concern in 2001; a decade later, a study in the journal JAMA Dermatology found that humans would have to cover 25 percent of their bodies every day for 277 years to get the same effect. If you’re still worried about the potential toxicity, you can opt for mineral sunscreens, which are just as effective and are often labelled as natural; they contain zinc oxide or titanium dioxide, which carry no risk of hormone disruption and do not cause allergic reactions.

Myth: Homemade sunscreens work

First came the homemade soap trend, then shampoo and now sunscreen. The latest craze is causing grave concerns among dermatologists. There are hundreds of recipes for homemade sunscreen online, some of which do nothing to protect you from light and even increase your risk of sunburn by using ingredients like plant products, which can make you light sensitive. “Using DIY sunscreens is playing Russian roulette with your skin,” says Beecker. “There’s no evidence that they work.”

Myth: You don’t need as much sunscreen with a base tan

“Don’t be fooled into thinking that if you tan, you don’t need to use as much sunscreen,” Lupin says. “A tan provides the equivalent of SPF 2 to 3, so you still need to use the minimum recommended SPF 30 sunscreen.”


There’s no such thing as a safe tan, Beecker adds, and a tan is actually a sign that your body is sensing mutations. “A tan equals DNA damage of your skill cells,” she says. “The cells are trying to put a little hat over themselves to protect and cover up their DNA, so they start making pigment like crazy.”

Myth: You don’t need to wear sunscreen when it’s cloudy or you're in the shade

Harmful ultraviolet rays can pass through clouds, so it’s important to wear sunscreen daily regardless of the forecast. While UVB rays get filtered on cloudy days, UVA rays don’t vary as much. “Even on a cloudy day, we’re still getting at least 80 percent of the harmful rays,” Beecker says. When the UV index is three or higher, sunscreen is needed. And while seeking shade is smart, it can’t completely protect you from sunlight, which scatters and reflects.

Myth: Children need their own sunscreen

Your beach bag just got lighter. Despite the number of children’s sunscreens on the shelves, the whole family can use the same product. Lupin says children’s sunscreens are largely a marketing strategy and often the only difference is that they have less or no fragrance. Some children’s products are also hypoallergenic, formulated for sensitive skin, “tear free” (they won’t run into the eyes) and free of PABA, an ingredient known to cause allergic reactions—all features you can find in adult versions. Children often have more sensitive skin, so if you want to switch to one sunscreen for the whole family, test it on your child’s inner forearm to see if they have a reaction.

Myth: You need different sunscreens for your face and body

While those pricey, purse-sized bottles of facial sunscreen may be temping, they’re more of a luxury than a necessity for most women. Still, a dedicated facial sunscreen is sometimes worth the splurge. “While you can technically use the same sunscreen for both face and body, the face can be more sensitive to the various ingredients and formulations of sunscreens,” says Lupin. “Patients with acne or rosacea may wish to use chemical-free sunscreens on the face, and lighter formulations that don’t run into the eyes are helpful.”


Sunscreen can also be found in a number of beauty products, including moisturizer, foundation, powder and lip gloss. Beecker says these products offer an excellent way to get additional coverage, but SPF 30 is still the recommended minimum, and some women may not be putting on enough of a given product to get the full effect. You’d have to put on a pretty thick layer of foundation to be fully protected—not a look most women want in the hot, humid summer.


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