For a long time now, we've been warned to cover ourselves with sunscreen every time we go out in the summer sun as a protective measure against skin cancer. However, despite the increasing use of sunscreens, skin cancer rates are still rising.
At the same time, researchers are discovering that deficiencies of vitamin D are climbing to epidemic levels. Sunlight is our primary source for this vital nutrient, and sunscreens severely limit your body's ability to manufacture vitamin D from sunlight.
If you really think about it,
avoiding sunlight completely just doesn't add up.
See Vitamin D from Sun Exposure for more details.
Ultraviolet light from the sun comes in two main wavelengths — longer-wavelength UVA and shorter-wavelength UVB. UVA constitutes about 96 percent of the total UV radiation, while UVB constitutes the other 4 percent.
UVA penetrates your skin more deeply and causes the most free radical damage. UVA rays are thought to be more responsible for wrinkling or premature aging of the skin.
UVB, which only penetrates the outer skin layer, is the primary cause of sunburn and non-melanoma skin cancer. UVB rays are also the ones that help your skin produce vitamin D.
UVA rays are quite constant during all the hours of daylight throughout the entire year. By comparison, UVB waves are lower in morning and evening and most intense at midday.
Scientists still are not certain which part of the spectrum is more responsible for causing skin cancer.
Physical-barrier sunscreens. Physical barrier sunscreens create a reflective surface on the skin that reflects UV light or scatters it off of the skin's surface. The active ingredients in these sunscreens are zinc oxide and/or titanium oxide. These types of sunscreens are very effective in blocking both UVB and UVA sun rays and are considered to be the safest sunscreens to use.
Chemical-barrier sunscreens, contain chemical ingredients that absorb UV light before it can cause any skin damage. These sunscreens (which includes most commercial brands) have long been effective against damaging sun rays, but some of them are known to have carcinogenic properties of their own. Most of the chemicals in chemical-barrier sunscreens have never been tested and approved for safety.
To get "broad spectrum" UVA-UVB protection with chemical-based sunscreens, you need to purchase a product with more than one active ingredient. Until recently, most chemical sunscreen products on the market primarily blocked UVB. However, the more chemicals present in the sunscreen, the more potentially hazardous they become.
See my page on Sunscreen Ingredients for more information on choosing the safest sunscreens.
Sunscreens with very high SPFs (50 or higher) are becoming more popular these days. They offer the promise of longer protection, but in real life, they don't work any better than a SPF 30 sunscreen. A product with an SPF of 15 blocks about 93 percent of the sun's UVB rays; an SPF 50 protects against about 98 percent. High-SPF products also tempt you to stay out in the sun longer, which increases your risk of skin damage.
High-SPF products also contain greater amounts of sun-blocking chemicals than low-SPF sunscreens. These ingredients may pose health risks when they penetrate through the skin, where they have been linked to potential hormone disruption.
Sunscreen Facts: It's better to use a sunscreen with a moderate SPF of 30 and reapply often. Typical sunscreen users apply only one-half to one-fifth the amount of sunscreen used in the laboratory SPF tests, so you may not be not getting as much protection as you think.
See my page on Best Sunblocks for information on my recommended sunscreen products.
There are only two scenarios where I'd recommend the use of any sunscreen at all:
1. When you're forced to be in the direct rays of the sun for a longer time than is safe. Maybe you work outdoors and are exposed to direct sunlight all day long. Or you have especially sensitive skin and can't be in the sun very long without burning.
2. When you take a winter vacation to the tropics and don't get the opportunity to gradually build up your sun exposure.
Sunscreen Facts: The most important thing to keep in mind is to not let yourself get sunburned. Moderation is the key; if you just keep your exposure at sensible levels, you're far better off not using sunscreen.
The International Agency for Research on Cancer recommends clothing, hats and shade as primary protection. Their report states,
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