It has been proven definitively that sunscreens and sun-protective clothing and practices do prevent skin cancer- the most common cancer seen in humans. Many of the most impactful studies have come from doctors work in Australia, the country with the greatest risk of skin cancer and biggest depletion of ozone to prevent ultraviolet (UV) light coming through the atmosphere.
- Do people have to use sunscreen if they are in the shade?
Yes, although you might feel you’re protected in the shade, certain UV rays, especially, UVA, is very reflective and bounces easily off of surfaces, such as sand, water, pavement, and even grass. UVA is present throughout the day (JK quote: “if you can see outside, UVA is present”), and throughout the year. Even if you wear a hat, the UVA light hits the ground reflects back up at you under the hat and can cause damage. A recent (2017) study reported in JAMA showed that 78% of people in shade who were not wearing sunscreen got sunburned over a 3.5-hour period!
- Should we worry about chemicals ingredients in our sunscreens?
When you really look at it, all ingredients are molecules, and a molecule is a chemical. Of course, there are many different kinds of chemicals, made up of different molecules in different combinations, and they act in different ways. The better language to use regarding sunscreen agents is “organic” and “inorganic”. The organic chemicals are carbon-based molecules, such as avobenzone and oxybenzone. The inorganic chemicals are minerals, such as zinc oxide or titanium dioxide.
There has been a lot of press regarding oxybenzone, and the question of whether it is a hormone disrupter, but the question arose from a study that has little relevance to the human experience- specifically the data on alterations in uterine growth in rats were based on data from the sunscreen being eaten, in amounts in excess of a human using the chemical on their entire body daily for over 70 years! As such the information from the rodent study is impossible to compare to the human experience. What we do know however is that oxybenzone is absorbed into the body from skin application to some degree and is excreted in milk and urine- the implications of this are unknown, at this time. The most cautious advice would be to avoid these agents during pregnancy and lactation, and to use the inorganic chemicals instead.
The best advice for evaluating sunscreen agents should come from your dermatologist- inaccurate data circulated on the internet can be highly misleading. One prime example of this is that sunscreens containing vitamin A-derived chemicals, such as retinyl palmitate, can cause skin cancer, is grossly wrong. In fact, the retinoids, including retinyl palmitate, can protect skin from cancer, and is preferentially leached from skin by sun. Of all the chemicals you put on your skin, retinoids have the greatest and broadest spectrum of activity in a beneficial regard, and in fact can protect your skin against cancer.
One last point about organic and inorganic chemicals in sunscreens: the former can decompose in heat, notably the heat of a car in hot weather with the windows rolled up. As a result, if you have a cream based sunscreen containing organic chemicals, this product will likely decompose in the heat of a car, and may not therefore provide you the protection you expect. If you are going to leave a sunscreen in the car, better to use a powdered sunscreen agent, composed of inorganic chemicals. These products are particularly useful for those in fields such as building and contracting, or occupations when an individual is outdoors for extended periods of time, such as fishermen, or golfers.
- What is the best sunscreen to use?
It has always been my contention that the best sunscreen is the sunscreen you use regularly every day! Take a look at your bottom- this skin is protected from sun every day, and not only looks beautiful, but is the actual age of your skin!
Beyond this, I recommend people use a sunscreen that blocks both UVA and UVB (also called “broad spectrum”), one that is SPF 30 or higher (remember though: the SPF rating ONLY applies to how well it blocks UVB! There is no equivalent rating scheme for UVA, and unfortunately the UVA spectrum is much broader and therefore more difficult to completely block than UVB. A quick rule of thumb is to look for high levels of zinc oxide in your product, as this chemical blocks both UVB and UVA quite well).
If you have sensitive skin or rosacea, stay away from the fragranced agents or those with lots of preservatives or plant extracts or other “natural ingredients” (remember, poison oak is all natural and all organic, and is not skin-friendly!).
Over the years, I have cherry picked favorite broad spectrum sunscreens for my patients to choose from which generally contain zinc oxide and are selective in the other ingredients- I insist on my patients trying out the sunscreens with samples if I have the luxury, as it is my firm opinion that if you like a sunscreen you will use it, despite the nagging of dermatologists, sisters, mothers, friends, or spouses! At our clinic, we pride ourselves in identifying broad spectrum sunscreens to fit the needs of clients with acne, rosacea, sensitive skin, pigmentation prone skin, folks who are working in hot humid or wet environments, and more.
- How much sunscreen should I be applying to my skin to be effective?
This is another difficult subject matter for the general consumer to wrap their head around. Unfortunately, the study criteria to identify the SPF rating of a sunscreen mandates that the test agent be placed on the skin in a very thick layer- MUCH thicker than an average consumer would apply generally. As such, the SPF rating provide by a particular product in life is much different than the rating that would be given in the laboratory. Most people put on a quarter of what is used to determine the SPF rating, and as such, only receive 1/4th the SPF protection! My general guidance to clients is to look for a sunscreen >/=SPF 30 that is broad spectrum, and reapply it every few hours. Spray sunscreens are not my favorite, as these can be inhaled and get into eyes.
- Does altitude play a role in UV exposure risk?
Absolutely! Those living or working at high altitude, such as pilots, have been shown to have higher rates of skin cancer, both melanoma and non-melanoma cancers. Levels of UV radiation increase by about 10% every 300 meters in altitude. Individuals living, working or recreating at high altitude need to protect their skin and eyes from the dangerous effects of UV exposure.
- Should people not outside or actively in the sun still wear sunscreen as a general rule?
Absolutely! While most sunburns occur during mid-day hours with full sun, in fact, the majority of our cumulative life sun damage occurs from “unintended exposure” when we are inside or walking in and out of buildings. UVA readily goes through windows, cloud cover, fog, rain, and is seen at the extremes of the day and all through the day, all year long. This fact is supported by the findings that individuals living in countries (such as the US) where driving is on the left side, there is a left sided predominance in skin cancer; other countries where they drive on the opposite side of the road, have a right sided predominance of skin cancer. Signs of aging too, such as loss of facial volume, pigmentation, rosacea or precancerous lesions, are also seen on the driving side of the body. Those working near a window experience similar consequences.
Our philosophy is that is important to both protect and repair concurrently, at all ages, with broad spectrum sunscreens and retinoids. Retinoids, which I call the “great skin normalizers” come in lots of flavors, and can be found to suit any skin condition at any age- these molecules can be paired with sunscreens and used to protect against skin cancer and premature aging- in a manner similar to fluoride protecting against tooth decay.