Sunscreen protects against two common forms of skin cancer, squamous cell carcinoma and basal cell carcinoma. However there is some evidence that several common sunscreen ingredients (namely, oxybenzone, benzophenone, octocrylene and octyl methoxycinnamate) may be linked to increased risks of malignant melanoma, a rarer but more deadly form of skin cancer. Other common sunscreen ingredients (namely, octinoxate and homosalate) are potential hormone disrupters.
Remember, too, as discussed last year, sunscreen use has been linked to vitamin D deficiency. Why is this important? Because there are indications that vitamin D deficiency may lead to skin cancer. Confusing, isn't it? We use sunscreen to reduce our risk of skin cancer, and then we learn that we may not be getting enough sun which our skin needs to produce the sun vitamin. In fact, vitamin D is produced in our skin after exposure to ultraviolet B (UVB) light. After some processing by our liver and then kidneys, this vitamin will defend our bodies against microbial invaders and also promote the healthy mineralization, growth and remodeling of bone. Finally, vitamin D also reduces inflammation (which we discussed last month).
The Environmental Working Group, an American watchdog on public-health issues, recently reviewed 1,755 sunscreens and found that only 8 percent blocked both UVA and UVB radiation, while also being free (or nearly free) of ingredients with known or suspected health hazards. Both UVA and UVB radiation from the sun (and tanning beds) can cause skin cancers after too much exposure, however for some reason most sunscreens only protect against the less harmful UVB radiation, and not against the more dangerous UVA component of the spectrum.
We can summarize the areas of concern:
- Potentially dangerous properties of some sunscreen ingredients
- Vitamin D deficiency caused by reduced exposure to ultraviolet light
- Incomplete protection against the full ultraviolet spectrum combined with increased time spent in the sun
There have been many sun exposure studies involving thousands of people over the past decade. Possibly due to the many kinds of sunscreen used, the amounts of sunscreen used, the self-reporting involved in most studies and the different countries (at varying latitudes) in which the participants lived, the results have often been contradictory if not inconclusive. Some show that use of sunscreen increases some forms of skin cancers while others show that their use reduces other forms of skin cancer, thus the controversy.
Here's my recommendation for staying healthy:
- Purchase sunscreen judiciously: it must block UVA and UVB radiation and contain none of the suspect ingredients.
- Use SPF 30 - SPF 50, those above SPF 50 have negligible extra benefit.
- Apply liberally when you expect to be in the sun for more than ten or fifteen minutes, especially at midday.
- Where a hat.
- Take a vitamin D supplement daily.
Finally, remember to give additional consideration to your lips. They are also at risk of painful burns and worse, lip cancer, too. Fortunately, safe lip sunscreens are available and should be purchased using the same considerations as outlined above for your skin sunscreen.
