The Science of Sun Protection
- Posted on: Jul 26 2018
Misinformation about sunscreen is common. Don’t let myths deter you from using it to protect your skin. There are many articles online and in the press that can cause confusion about the benefits and possible harms of sunscreen. With the incidence of skin cancer on the rise, I think it is pertinent to examine and outline the science of sunscreen and skin protection. Here are some common questions asked and answered:
ARE THERE CERTAIN CHEMICALS IN SUNSCREEN THAT PEOPLE SHOULD AVOID?
There are 2 types of sunscreens:
CHEMICAL BLOCKERS contain chemicals that filter out the sun’s UV rays. These chemicals are typically avobenxone, octisalate, oxybenzone, octinoxate and octocrylene. Octinoxate and oxybenzone have been found to be potentially damaging to coral reefs and in the state of Hawaii there is now legislation in place to have sunscreens containing these chemicals banned by 2021. There have been studies with rats showing that some of these chemicals may be hormone disruptors, but to date, the studies involved feeding oxybenzone to the rats in large quantities to produce the results. Even if you avoid sunscreens with oxybenzone, you many encounter it in other products including plastic, hairspray and nail polish. At this point in time, I recommend a physical blocker as described below.
PHYSICAL BLOCKERS reflect UV rays from the sun and contain one or two active ingredients – zinc oxide and titanium dioxide. These days, there are excellent preparations that contain nanoparticles of these ingredients which makes them easier to apply and feel light on the skin. We no longer need to associate zinc lotions with the greasy white sunblocks of the past.
DOES SUNSCREEN PREVENT SKIN CANCER?
There are excellent studies that show that the use of sunscreen protects against all 3 of the most common skin cancers – squamous cell carcinoma, basal cell carcinoma and melanoma.
DOES EVERYONE NEED TO USE SUNSCREEN?
Darker skinned people have a lower incidence of skin cancer; however, remember that sunscreen blocks out UVA (ageing) and UVB (burning rays). The benefit for skin is therefore two-fold and helps slow the ageing effect we see on skin due to sun damage.
IF I USE SUNSCREEN DAILY, WILL I DEVELOP A VITAMIN D DEFICIENCY?
In our northern climate, it is now recommended that we all take a Vitamin D supplement in the winter. In the summer, 10 to 15 minutes in the sun should fulfill this quotient. Other options are a diet rich in Vitamin D containing foods, eating fortified foods and taking a supplement. Vitamin D supplements suggested are 400 iu for infants, 600 iu for age 1 – 70, and 800 iu for those over 70. Concern about Vitamin D should not be a reason to avoid sunscreen. Vitamin D levels can be checked by your physician but there may be a cost for this procedure.
SUMMARY OF SUN PROTECTION
- I recommend finding a physical sunscreen that you like so that it can be used daily as part of your skin protection (yes even in the winter). There are many formulations now that are easy to use and feel good on your skin.
- Don’t just depend on sunscreen. Sun protective clothing is available and very helpful for exposed arms, neck, and legs.
- Chemical sunscreens (if you choose to use them) need to be reapplied every 2 hours as recommended by Health Canada.
- Physical blocks may last longer and there are now mineral sunblock powders available that can easily be applied over the already applied fluid block that was put on in the morning. I find these sunblock powders great to use on babies and children. They are easy to apply and contain no potentially harmful chemicals.
- After sweating or playing in the water, your physical sun block should also be reapplied.
HOW DO I KNOW IF I HAVE A SKIN CANCER?
Your family physician is able to check out any concerning lesions you may have on your skin.
ACTINIC KERATOSES are precancerous lesions that can be treated with prescription cream or cryotherapy in your physician’s office.
BASAL CELL AND SQUAMOUS CELL CANCERS will need biopsies and sometimes surgical excision, although small basal cell cancers can sometimes also be treated with prescription creams under physician supervision.
MELANOMAS are the most dangerous and will require surgical excision and follow up.
WHAT ABOUT BROWN SPOTS AND OTHER SUN DAMAGED AREAS?
There are many options now for treating solar lentigines, seborrheic keratoses, and other sun damaged areas. These include laser therapy, cryotherapy, fractional resurfacing, and chemical peels. Daily treatment and protection with effective skin care products is essential. The products you should apply daily are:
A – Vitamin A (Retinol) which treats brown spots, acne, and helps with collagen growth
B – Sun Block from the sun as described above.
C – Vitamin C is an antioxidant that protects, nourishes, and treats discolouration.
Laser therapy utilizes either a 532 or 1064 laser to selectively target brown spots or treat small red vessels on the face and chest. Intense pulsed light (also known as a photofacial) can also be used to treat reds and browns, although extreme care must be made before using this modality on some brown pigment because if it is melasma, it may make it worse. A thorough assessment by a trained physician prior to treatment will help avoid this pitfall. In some darker skin types, treatment with lightening creams and the use of glycolic peels is a safer option. Individual seborrheic keratoses (larger brown spots) can be treated with cryotherapy (dry ice) in some instances. Fractional resurfacing is a deeper treatment and can be used to effectively treat the fine lines and changes in pore size that occur with photodamage from the sun.
- SUN PROTECTION IS ESSENTIAL.
- ACCURATE DIAGNOSIS OF LESIONS IS A TOP PRIORITY
- EFFECTIVE TREATMENT OPTIONS FOR ALL TYPES OF LESIONS ARE AVAILABLE.
Posted in: Skin Care