What's the Most Dangerous Part of Sun Exposure?

Although the risks of sun exposure have been greatly overblown, anyone who has ever gotten a sunburn knows that too much sun genuinely can damage your skin. What is less well known is that for many years, sunscreens only protected you from the potentially beneficial, vitamin D producing UVB rays, while letting through skin-damaging UVA light.


Both UVA and UVB can cause tanning and burning, although UVB does so far more rapidly. UVA, however, penetrates the skin more deeply than UVB, and may be a much more important factor in photoaging, wrinkles and skin cancers.


Even today, while most sunscreens do a good job blocking UVB, fewer filter out all of the UVA.

That means they do not help to prevent the beginnings of melanoma formation. In fact, a sunscreen without adequate UVA protection can end up increasing your risks. If you think you are protected by sunscreen, you are likely to stay out in the sun longer -- and all the while, you will be soaking up the highly penetrating, wrinkle and cancer causing UVA radiation without the warning sign of a burn (remember that a UVA burn takes much longer to appear).


I’m not a big fan of sunscreen use on a regular basis; even when it works, it blocks your body’s natural production of vitamin D. But in situations where you must be out in the sun long enough to burn, be sure to use a product that protects against both UVA and UVB, such as Natural Sunscreen, which uses a titanium dioxide/zinc combination that reflects both types of rays -- while also giving you a beautiful, glowing and healthy tan.

Dr. Mercola's Comments:

If you live in the northern hemisphere, summer has officially arrived, which is something I’m truly thrilled about, because I believe we ALL need optimal amounts of healthy sun exposure.

When you expose your bare skin to the sun, the ultraviolet B rays metabolizes and gets converted into vitamin D. It is estimated about 85 percent of the U.S. population is deficient in vitamin D, which causes 2 MILLION people to die every year from cancer.

Yes, cancer -- not heart disease -- is now the number one killer.

I’m a firm believer that your best source of vitamin D is from healthy sun exposure, not from swallowing vitamin D capsules, as taking vitamin D orally can easily result in overdosing. I believe in this so much, I actually wrote a book about it, called Dark Deception, which is coming out shortly.

Not All of the Sun’s Rays are Created Equal

Now, there’s an important distinction that you need to be aware of when it comes to healthy exposure to the sun’s rays, and that is the difference between its two primary wavelengths: ultraviolet A (UVA) and ultraviolet B (UVB).

UVB is the more beneficial of the two, as this is what converts into vitamin D. UVA, however, is now believed to be a primary risk factor for cancer. It’s therefore very important to understand the difference between these two wavelengths, so that you can take proper care of yourself and your family.

You see UVB has a wavelength that is more easily filtered through the atmosphere, so on a cloudy day you won’t get as much of that radiation on your skin to make vitamin D. However, UVA does not get filtered as well and will penetrate the atmosphere more easily, so it will STILL increase your risk of cancer on cloudy days, in the early morning and late afternoon, so you need to be very careful even under those conditions.

How do You Know You’ve Had Enough Sun Exposure?

Optimal sun exposure is dependent on your skin color. Caucasians and others with paler skin may need just a few minutes in the sun at the beginning of the season; you only want your skin to turn the lightest shade of pink. At that point you’ve reached your saturation point and your body will not produce any more vitamin D.  

You can create as much as 20,000 units of vitamin D per day if you have enough of your uncovered skin exposed to the sun. The beauty of getting your vitamin D from healthy exposures to sunshine is that your body has this built-in feedback loop that prevents you from overdosing on it.

After that, however, you’re only increasing your chances of getting burned, which is something you definitely want to avoid.  There is NO additional benefit to staying in the sun any longer. You only risk damage by extending your time in the sun.   

It’s not like your gas tank. Your body can only produce a limited amount of vitamin D every day. Once it reaches its limit you only cause damage by going beyond that amount.  However, once you have a tan you can spend much longer amounts of time in the sun. 

It is also important to know that if you have darker skin, reaching this equilibrium point can take two to six times longer (or up to an hour or two), depending on your pigmentation. 

What’s the Best Way to Protect Yourself From Too Much Sun Exposure?

Once you’ve had enough or you want to limit your exposure, the best way to do so is by wearing a long sleeved shirt, pants and hat, or stay in the shade.

However, sometimes that’s not entirely practical. You may be at the beach or by the pool, and your children enjoy playing outside for hours on end, so many resort to using sunscreens.

There are a couple of very important considerations you need to know about when selecting sunscreen. First of all, many of the sun lotions on the market do not screen for UVA. It’s very important to make sure the sunscreen you select screens for UVA, otherwise you’re only screening for UVB, which effectively stops your production of vitamin D, while still increasing your cancer risk!

Secondly, many of the chemicals used as filtering agents are extremely toxic, and Octyl methoxycinnamate (OMC), which is present in 90 per cent of sunscreen brands, actually undergoes a chemical reaction when exposed to sunlight, which causes it to turn extremely toxic. Other common sunscreen ingredients have been found to easily penetrate into your blood stream, including:

  • 2-hydroxy-4-methoxybenzophenone
  • 2-ethylhexyl-p-methoxycinnamate
  • 2-ethylhexylsalicylate (octylsalicylate)
  • salicylic acid 3,3,5-trimethcyclohexyl ester (homosalate)

If you’re using sunscreen, please make sure you use a product that protects you from both UVA and UVB rays, and is non-toxic. My team has done an exhaustive search and found one such option, called Natural Sunscreen.  It uses a titanium dioxide/zinc combination that reflects both types of rays -- while also giving you a beautiful, glowing and healthy tan. There are others out there, but this is one product that I can confidently promote as a safe and non-toxic option.