Dr Shannon Humphrey is a Vancouver-based dermatologist, a partner in Carruthers and Humphrey Cosmetic Medicine, and a Clinical Assistant Professor at UBC’s Department of Dermatology & Skin Science. Here, she answers burning questions on sun safety and sunscreen.
What is the safest and most effective way to protect the skin from UVA and UVB damage?
Have a comprehensive sun safety strategy that includes:
– avoiding the sun and opting for shade whenever possible;
– choosing the safest times for sun exposure (i.e. avoiding the sun between 10am and 2pm when its strength is most intense);
– wearing sun protective gear, including wide-brimmed hats and long sleeve shirts;
– using a broad-spectrum sunscreen that protects against both UVA and UVB damage (rays that cause sunburn, skin cancer and photo-ageing);
– For consumers who are still concerned about chemical sunscreen ingredients simply choose a mineral-based sunscreen with zinc and titanium.
How should we choose and apply sunscreen?
I recommend at least SPF 30 for daily use and at least SPF 50 for days when you intend to spend time in the sun.
An important and often overlooked element to sunscreen efficacy is application. If you apply SPF 30 and only apply a quarter of the required amount (and this is really common) you will only be getting a quarter of the SPF protection. That’s why choosing an even higher SPF is going to give you better protection. The Canadian Dermatology Association recommends two to three tablespoons of sunscreen to cover your body and one teaspoon to cover your face. It’s more than you think! Reapplication is also vital – every two hours and after swimming or sweating.
Which is more harmful: Sunlight, or sunscreen?
Ultraviolet light exposure is the most preventable risk factor for skin cancer. Sunscreens (mineral and chemical) have been used for decades by huge proportions of the population and there are no signals that they pose safety concerns in people.
In October 2013, the Canadian Cancer Society released a statement that ‘after a thorough assessment of the current research, [they] believe that oxybenzone, retinyl palmitate and parabens in sunscreen do not pose a cancer risk.’ Consumers in Canada can watch for the Canadian Dermatology Association logo when shopping for sunscreen – these products have been reviewed by CDA member dermatologists as part of the CDA’s Sun Protection Program and have met all the approval criteria, through independent laboratory testing.
What are the dangers of oxybenzone in sunscreens? Can it really cause hormonal or fertility problems when used in sunscreen?
Oxybenzone is commonly used in sunscreen because it is one of the few ingredients in sunscreen that effectively protects our skin from both harmful UVA and UVB rays. As we know, overexposure to either UVA or UVB rays can cause cancer. No data shows that oxybenzone causes hormonal problems in humans or, in fact, any significant health problems.
What are the harmful effects of topical application of retinyl palmitate? Is it possible that when used in sunscreen it can cause or accelerate cancers?
Retinyl palmitate is a form of vitamin A (retinol). We know that retinoids are widely used for a number of skin conditions, and there is no evidence indicating that they increase the risk of cancer.
Some drugs are given through the skin, so are oxybenzone and retinyl palmitate getting into our bloodstreams?
Although oxybenzone is absorbed by the body, it is then excreted and does not accumulate. Sunscreen is applied to the stratum corneum, the outermost layer of skin, which is made up of dead cells. With any topical cream, sunscreen or drug, a very tiny amount may be absorbed. Drugs like Fentanyl are designed to be absorbed when they are applied as patches, but they have ingredients added specifically to enhance absorption into the bloodstream which sunscreens and other skincare products do not.
Is it best just to get a ‘base tan’ at a tanning salon before going into the sun?
No. You can read more about why here.
Skin cancer incidence has risen alongside sunscreen use, so doesn’t that mean that sunscreen causes cancer?
No. Increased incidence of skin cancer is down to a combination of four factors: increased reporting (we didn’t used to report); increased detection (we didn’t used to screen); increased UV intensity due to ozone depletion; and most importantly a demographic shift (we are all living longer).