Sunscreen - friend or foe?

[NorthShore]

I've been hearing bad things about sunscreen, so I made the mistake of googling and there seems to be a sizeable minority opinion out there that the use of chemical sunscreens can do more harm than good when it comes to protecting against skin cancers.

There is universal acceptance that they are very effective in preventing sunburn (we all know that first hand), but less agreement that preventing sunburn = preventing skin cancers.

More specifically most of the cons I read involve the various chemical compounds used to block or absorb UVA and UVB being highly reactive; in other words when absorbed into the skin they absorb and convert harmful UV radiation to harmless heat (which is good), but the compounds themselves are photo reactive and produce free radical molecules that do more cellular damage than the UV would.

For now, I am going to try one of the organic sunscreens containing zinc oxide, which to my way of thinking is the equivalent of rubbing mud on my skin. Zinc oxide is a mineral that is not absorbed into the skin. Unfortunately the organic products also seem to contain titanium dioxide, which while also a naturally occuring mineral and also is not absorbed into the skin, does create carcinogenic radicals via a photocatalytic reaction (i.e., exposure to light).

It seems like a couple of decades of conventional wisdom about sunscreen is under attack and I am curious about the opinion and practices of others on this forum with regard to sunscreen.

Ed

 

[DougPaul]

I don't have any personal knowledge of the chemical risks, but the latest issue of Consumer Reports just happens to have a report which includes some comments on the subject:

From http://www.consumerreports.org/cro/magazine-archive/2011/july/health/sunscreens/overview/index.htm

Almost every tested sunscreen contains some ingredients associated with adverse health effects in animal studies. Oxybenzone and other endocrine disruptors may interfere with hormones in the body, and nanoscale zinc and titanium oxides are linked to problems such as potential reproductive and developmental effects.

Retinyl palmitate (look for it among inactive ingredients), a type of topical vitamin A, is an antioxidant that animal studies have linked to an increased risk of skin cancers. In skin, it converts readily to retinoids, associated with a risk of birth defects in people using acne medications containing them. As a precaution, pregnant women may want to avoid sunscreens with retinyl palmitate. (They're footnoted in the Ratings.)

More research is needed, but as of now, the proven benefits of sunscreen outweigh any potential risks.

BTW, the term "organic" may not have a legal definition with respect to sunscreen--and nature produces plenty of harmful chemicals. I personally wouldn't pay any attention to claims of a sunscreen being organic.

Doug

 

[BadgerGirl]

Sunscreen prevents the skin from absorbing vitamin D, which is a potent cancer fighter.

You just have to be smart about sun exposure, especially above the tree line. We weren't meant to be vampires, but those of us with northern European skin are more sensitive to sun.

Try not to burn, wear a wide brimmed hat, don't stress.

Who knows what kinds of nasty oxidation process occurs when chemical sunscreens bake in the sun. I am sure they're letting off a host of free radicals.

I have fish-belly white skin, so I protect it with hats, clothes, and shade, but if I were going to be on a huge light-reflective rock above the tree line or out on a sailboat all day, I'd goo up with physical sunscreen (the white stuff those of us who are old enough should remember seeing on lifeguards' noses back in the day).

I'm at work right now, so I can't look for any peer-reviewed studies, maybe later.

Thanks to Barbarossa for bringing me out of hiding. He knows how I feel about sunscreen.

As for organic, I wouldn't spend more money on that. Titanium and zinc are organic minerals. Anthrax and botulism are organic, too.

 

[Tom Rankin]

As for organic, I wouldn't spend more money on that. Titanium and zinc are organic minerals. Anthrax and botulism are organic, too.

Apparently so is water!

 

[NorthShore]

I'm not hung up on the term organic; the zinc oxide products just seem to ubiquitously use that term despite whatever else is in the formulation. The way I see it, there are three best options I've heard for avoiding sunburn:

• Stay out of the sun during peak hours.
• Cover up. This can include clothing as well as coating yourself with mud (be careful where you get your mud; hippo and pig wallows not recommended for multiple reasons ).
• Good old fashined zinc oxide.

It appears that even the new fangled zinc oxide ("nanoscale" particles to eliminate the "white stuff on my nose" syndrome), has some serious problems.

The advice offered in this thread seems solid. We have to manage the conflicting goals of avoiding overexposure to the sun and avoiding sunscreen products. I'm not much of a tanner, so that kinda sucks especially since I like it above treeline. A safe and effective product seems elusive.

If I couldn't cover up or use the old school zinc, I'd still chose to risk the chemicals over a severe burn. The key is probably avoiding that situation.

Sorry to be such a downer, but I had one of those "am I really doing the right thing" moments while smearing a common sunscreen product on my younger son last weekend. My wife who was away during the day smelled it on him that evening and commended my dilligence. Thats when I really started wondering if I had done the right thing (sorry dear, couldn't help myself)

 

[roadtripper]

All I know is I avoid sunscreen most of the time because I want all that vitamin D. The true powers of Vitamin D continue to be realized by researchers and I don't think they are anywhere near done yet.

 

[chipc]

If you can get access to this article, it's an April 2011 review covering sunscreens and discusses vitamin D issues as well. (Yes, it's a bit techie).

http://www.ncbi.nlm.nih.gov/pubmed/21292345

Their summary statement is as follows:

"In summary, the efficacy of sunscreens in reducing photoaging and skin cancers is widely documented. UVA- and UVB-blocking products protect against sunburn as well as more subtle suberythemal skin damage. While there may be concerns over the longterm safety of UV filters, the benefits of sunscreens clearly outweigh their potential risks. However, the principal barrier to attaining these benefits is patient compliance. Taking advantage of improved technologies and product efficacy may require patient education and public health measures encouraging sunscreen use. New technologies that improve aesthetics may also help to increase compliance, thereby decreasing the incidence of skin cancer and the severity and extent of photoaging. "

 

[roadtripper]

And how about the theory that the less sun you get (because of the sunscreen), the more harmful the sun is when you actually get it?

I'd be curious to see skin cancer rates of developed countries near the equator that get tons of sun.

 

[TEO]

If sunscreen wards off severe 1st degree and 2nd degree burns, which in my experience it has, I'd say it's a friend.

 

[erugs]

I put it on where I need it most. My nose. Otherwise, I'm fortunate enough to burn less often than some of my friends. I "should" have good levels of Vit. D, but according to my doctor I am at very low levels and have to take a supplement.

Don't get me started on sun and Doxycycline - I became a leather faced and pins-and-needle armed Lyme victim. Other antibiotics don't have that same effect. Being on Doxy was one way to literally lose face.

 

[erugs]

This is about Vit. D and describes a good reason to be in the sun getting all of the D you can:

Update on vitamin D deficiency and heart attacks:

Ninety-six percent of 239 people suffering acute heart attacks in 20 hospitals had very low levels of vitamin D.

They were also markedly overweight and had high levels of parathyroid hormone (American Journal of Cardiology, June, 2011). Normal vitamin D3 level is above 30 ng/ml (75 nmol/L).

The single highest risk factor for a heart attack is diabetes. The major function of vitamin D is to increase calcium absorption from the intestines. When blood levels of vitamin D are low, ionized calcium drops, causing the parathyroid glands to put out large amounts of parathyroid hormone. This blocks insulin receptors to cause diabetes (Journal of Nephrology, 06/06/2011).

If your vitamin D3 level is below 30 ng/ml, your doctor will probably recommend more sunlight or vitamin D pills.

from Dr. Gabe Mirkin

 

[DougPaul]

And how about the theory that the less sun you get (because of the sunscreen), the more harmful the sun is when you actually get it?

My guess is far-fetched except for tanning. (Tan protects the skin to some degree.)

I'd be curious to see skin cancer rates of developed countries near the equator that get tons of sun.

Check out Australia--there are lots of fair skinned people from Europe (eg Irish) living there. Skin cancer is a major concern--there have been advertising campaigns to promote sun protection: "Slip, Slop, Slap" (slip on long sleeved clothing, slop on sunscreen, slap on a hat). http://www.youtube.com/watch?v=nztHSVvZUoU http://en.wikipedia.org/wiki/Slip-Slop-Slap (Don't forget that Australia is close to the Antarctic Ozone Hole and gets ~15% more UV than the Europe. http://www.theozonehole.com/australianskincancer.htm)

A certain amount of UV is good because it helps the skin to produce Vitamin D, too much, of course, can cause cancer. About 20min of unprotected exposure is enough for light-skinned individuals. (3-6x longer for dark-skinned individuals.) http://en.wikipedia.org/wiki/Vitamin_D

Doug

 

[Little Rickie]

It seems like a couple of decades of conventional wisdom about sunscreen is under attack and I am curious about the opinion and practices of others on this forum with regard to sunscreen.

Ed

Like most things in life if used in moderation when needed you will proabably be fine.

Need more vit D? Drink more milk and eat more fish.

 

[DougPaul]

If your vitamin D3 level is below 30 ng/ml, your doctor will probably recommend more sunlight or vitamin D pills.
[/B]

According to http://en.wikipedia.org/wiki/Vitamin_D, production of vitamin D saturates after ~20 minutes of exposure. Large doses of vitamin D from pills can be toxic, but people do not exhibit vitamin D toxicity from sun exposure.

Also, a study of dark-skinned African-Americans found them to have lower levels than light-skinned Euro-Americans without ill effect. Perhaps one's vitamin D requirements depend on one's ancestry... (same ref)

Doug

 

[Kevin Rooney]

Two questions -

Do the various sunblock lotions prevent the production of Vitamin D?

How much skin (square inches?) needs to be exposed in order to produce Vitamin D?

 

[DougPaul]

Two questions -

Do the various sunblock lotions prevent the production of Vitamin D?

Yes.

How much skin (square inches?) needs to be exposed in order to produce Vitamin D?

Duration, time of day (and clarity of the sky etc), and skin tone (light-dark, tanning etc) are also factors. According to http://en.wikipedia.org/wiki/Vitamin_D vitamin D production saturates after 20 min for light-skinned individuals. I don't recall if the ref gives a desired skin area, but you might be able to work out an estimate from the numbers in it.

Doug

 

[Little Rickie]

I don't think it takes much skin exposure to get your vit D. You can get what you need by going for a walk outside in the winter a few days a week.

You'd have to slather on a whole lot of sunscreen on all your exposed skin to totaly block out the vit D thing and that of course would be excessive.

So back to my moderation statement and don't worry about vit D.

 

[Maddy]

The more I read all these studies, the more I conclude that we appear to know precious little about anything.

My philosophy is "go out, live life, and stop thinking about it.".

"Life causes death!" This is one of the most profound and believable statements I have ever heard. A "truism" if I ever heard one.

 

[erugs]

Kevin, from the Office of Dietary Supplements:

"The factors that affect UV radiation exposure and research to date on the amount of sun exposure needed to maintain adequate vitamin D levels make it difficult to provide general guidelines. It has been suggested by some vitamin D researchers, for example, that approximately 5–30 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis and that the moderate use of commercial tanning beds that emit 2%–6% UVB radiation is also effective [6,19]. Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement to achieve recommended levels of intake."

See: http://ods.od.nih.gov/factsheets/vitamind/

My level is 40, way below what it should be and I don't avoid the sun, except I don't get it during the work week. It just doesn't come through the glass near my cube.

 

[erugs]

And yes, Kevin, Sunscreen blocks Vitamin D.