Blog Articles
SUNSCREEN BLOG
- I heard that most sun damage is done before age 21; therefore do I really need to wear sunscreen now?
- Can the chemicals in artificial tans cause cancer?
- Anything over 15, doesn’t really matter?
- What does chemical free mean, aren’t they all chemicals?
- How often do I need to reapply?
- What other factors increase skin cancer?
- Can sunscreens cause cancer?
- Do sunscreens prevent cancer?
- Don’t we need to get vitamin D from sun exposure?
- What happens if we wear sunscreen all the time?
- Are sun tanning beds safer than the sun?
- Is it really bad to lie out?
In being a dermatologist I have heard a lot of questions about sunscreens from patients, family, friends and unfamiliar people at different gatherings. The answers are not very simple. But fortunately these questions have all been answered to a high degree of certainty.
The sunscreens block ultraviolet radiation from the sun by a chemical reaction that absorbs sunlight or physically blocks the sun like a wall. Chemical sunscreens are more cosmetically acceptable in that they do not have to be opaque. Chemical reactivity increases the chance of allergies and many people have heard about PABA. PABA caused a lot of allergies. It’s been years since I have seen an allergy to sunscreen in my office. That doesn’t mean that they do not occur but are now much rarer. I still recommend testing a small area on the neck with any new sunscreen or topical potion including makeup, moisturizers, etc. before applying it all over the face. Chemical free sunscreens contain titanium and zinc and do a much better job of blocking all of the sun’s rays. They can make an excellent base for makeup and micro sizing the molecules can make the cosmetic acceptability very high but also increase the cost. In addition they are perfect for children, especially infants because they do not seem to burn eyes and allergy potential is almost zero. Unfortunately chemical free sunscreens are rarely waterproof.
The relationship between cancer and sunscreens is a very difficult question to answer but I will try. By definition the number on a sunscreen refers to stopping sunburn which is caused primarily by ultraviolet B which hits the top layer of skin and burns it as well as causing actinic keratosis, squamous cell carcinomas and basal cell carcinomas. A number 15 means that it takes 15 times as much sun to burn the skin. To determine the number assigned to the sunscreen, patches are placed on the backs of subjects and different amounts of artificial sun light are exposed. It makes sense that stopping sunburns will also assist in decreasing skin cancer. It takes years for the sun to cause cancer therefore years to have answers.
Sunscreens have been shown to decrease skin cancer. I remember a study when I was in my dermatology training that asked students what is the purpose of sunscreen. The majority answered: “to get a tan”. I hope that this is hard for young people to believe but anyone raised in the 1970’s remembers a sunscreen billboard showing a bronze baby with a dog pulling at the swimsuit showing white skin. Only recently have sunscreens done a good job of blocking ultraviolet A. Ultraviolet A deeply penetrates the skin causing wrinkling, freckling, liver spotting, probably melanomas, potentiates damage from ultraviolet B, can cause sun burn if in high enough quantity and damages the immune system of the skin. Sun tanning beds are almost pure ultraviolet A and in some states have a label warning about causing skin cancer and aging. Sounds similar to cigarettes don’t it? I tell patients that smoking once was considered cool. People who are interested in their health have a similar opinion of tanning as they do smoking, not cool! One reason for the epidemic of skin cancer we have now is believed by many to be in the use of low number sunscreens and lying out in the sun. You actually get a lot more sun exposure getting the same tan. Therefore I strongly believe that using a sunscreen while lying out dramatically increases aging and cancer. I tell people to watch the movie: There’s Something about Mary. If they want to look like the lady who tans all the time it’s their choice. Similar to that, it’s their choice to smoke, drink excessively and do other not so intelligent things. Life is about making choices.
In reference to the quote that most of the damage is done before age 21, I believe that there is truth to this statement. Protecting young people is extremely important. However, men who go bald frequently have much more cancer on top of their head than they do on the face. One of my father’s favorite quotes was that the old sun sets you up and the new sun does you in. He required his bald patients to wear a hat to his office before he would see them. Within minutes of strong sun exposure, immune competent cells called Langerhans cells can disappear in the skin.
Xeroderma pigmentosa is a condition whereby the immune system does not stop cancer from forming. Children perish from skin cancer. Although it’s easy to make the argument that its best not to expose the body to chemicals, artificial tans would not be approved it they were known to cause cancer. I have seen nothing in the medical literature about cancer causing chemicals in any artificial tan. A choice between a natural tan and an artificial tan should be easy after reading this blog.
As I stated earlier, a number 15 means that you get 15 times as much sun before you burn. Unfortunately this says nothing about ultraviolet A. The sunscreen testing system in the US is less than stellar. I have started selling an Australian sunscreen because they have a much more practical method of testing. In the United States , sunscreen manufacturers typically use two or three times as much sunscreen as the average person and waterproof is tested after someone has been sitting without moving in the water. If you start out with a 45 and you apply half of what they used to determine this number and wiped sweat off your face, you are probably down to a 15 or lower. Big numbers are better if sweating or swimming. A 15 is adequate only if you are not in strong sun.
Vitamin D is still being worked out. As confident as I am and of all the above information I am still watching this area closely. And there are some statements I am comfortable with. A small amount of sunlight early or late in the day should be sufficient for almost everybody. Taking oral vitamin D will probably suffice if there is any question about deficiency. I know this was a long blog but what would you expect if you ask a surfer about waves?
