This is sort of a tangent but I’ve run into it while I’ve been researching cruelty-free sunscreens. Basically, I realized that most sunscreens don’t protect people from skin cancer — that only sunscreens with avobenzone, mexoryl, octocrylene, titanium dioxide, or zinc oxide in them will.
Why will these ingredients protect everyone from skin cancer? I read a ton of articles and blogs on this, and I finally determined the reasoning. Basically, there are two types of wavelengths in sunlight — UVA rays and UVB rays. People used to think that UVA rays were harmless and UVB rays caused skin cancer. This seemed logical because UVB rays were shown to cause tanning. So people slathered on sunscreens that protected them against UVB rays but did nothing to protect against UVA rays and spent more time out of doors exposing themselves to skin cancer than they would have if they hadn’t worn any sunscreen at all, and skin cancer rates started to skyrocket. Rates of sunscreen usage and skin cancer have increased dramatically since the 1970s – in the U.S. alone, new cases of melanomas have increased 150%, and deaths from melanomas have increased by 44%. A recent Australian study confirmed that the reason for this is that UVB-blocking sunscreens are not very effective at preventing melanomas. So scientists are attempting to determine what causes deadly melanomas, if it isn’t UVB rays, and many of them suspect that it’s the other ultraviolet component of sunlight — UVA rays.
So, I think it’s important to block those skin-cancer-causing-UVA rays. But will buying a “full spectrum” sunscreen block UVA rays? No. The Skin Cancer foundation recommends only five types of skin-cancer-blocking ingredients — avobenzone, mexoryl, octocrylene, titanium dioxide, and zinc oxide. If you do not buy a sunscreen with one of these ingredients, it will not protect you from skin cancer. Just be sure to turn over any sunscreen bottle you find in a store and read the active ingredients list to make sure it has avobenzone, mexoryl, octocrylene, titanium dioxide, or zinc oxide in it. Avobenzone is the best one — mexoryl is not available in the U.S. right now (but is rumored to begin to be available in the fall), octocrylene has weird hormone issues, and titanium dioxide and zinc oxide tend to cause streaks (yuck). Alba Botanica makes some great cruelty-free sunscreens with avobenzone in them that I really like — a facial sunscreen, a facial moisturizer with sunscreen, a water resistant sunscreen, and a kids’ sunscreen. I haven’t tried the water resistant sunscreen or the kids’ sunscreen, but the facial sunscreen and the moisturizer are excellent.
I figure that within the next five years the FDA or some government authority will require all sunscreens to have UVA-blocking ingredients if they wish to call themselves sunscreens, but in the meantime, it’s probably a good idea to think about buying one with avobenzone in it.
Update 04/21/07: I’ve read some rumors that avobenzone may “generate free radicals” or something like that. I’m not really sure what those are, and the only sites I’ve found that talk about this do not cite any scientific sources, and the Environmental Working Group, which I think is a reputable site, lists avobenzone of having a score of 0.0 on the toxic scale. So I’m leaving my recommendation of avobenzone up (for now). As soon as I find any articles saying that avobenzone is toxic on PubMed I shall stop recommending it. In the meantime, avobenzone does block UVA rays, which have caused numerous skin cancer deaths over the past decades, so I’m sticking with it. If you click on the link above, and type in “avobenzone,” you’ll see 41 scientific articles that have tested how well avobenzone protects against UVA rays.
Response requested:
Hello Emily,
Thank you so much for this information on sunscreen and UVA rays. I have been searching many sites on this topic and this has been the most helpful yet!!
I am wondering if in your research you have found any info on what percentage of Avobenzone is recommended for the best UVA protection.
Thank you for your time,
Christy Woods
Comment by Christy — June 21, 2007 @ 2:44 pm
Hi Christy,
So glad to have been of help!
It’s been a while since I’ve researched skin cancer and UVA rays — I don’t remember reading anywhere about what percentage of avobenzone is recommended, but I’ll do some surfing and get back to you
Comment by Emily — June 23, 2007 @ 4:58 pm
Hi Christy,
I’m still looking for avobenzone percentage recommendations — so far I’ve only been able to find one (non-academic) source — according to a news article, Dr. Dee Anna Glaser, a cosmetic dermatologist and professor of dermatology at St. Louis University School of Medicine, recommends “at least 2 percent avobenzone.” (http://www.stltoday.com/stltoday/lifestyle/stories.nsf/healthfitness/story/DD96BD45B139D82E862572FB007CA048?OpenDocument)
I did find another website that suggests that avobenzone is only legal in the U.S. up to a 3% formulation (http://www.totalblock.com/science.html)
So, I hope that helps, and if I find any Pubmed articles on avobenzone percentages I’ll be sure to post them here.
Emily
Comment by Emily — July 8, 2007 @ 9:17 pm
i work out in the sun all day long…thanks for posting this info…something to look into
Comment by ashley mcfee — December 27, 2007 @ 1:07 pm
Hi Ashley — welcome to my blog! I’m so glad this helped you.
Comment by Emily — January 6, 2008 @ 9:40 pm
Very cool blog. One quick tip…. A family member is a melanoma specialist at one of the big cancer hospitals, MD Anderson, in Texas. She informed me that the only sunscreens that truly help protect against skin cancer are those that contain zinc. Zinc and only zinc. Thanks for all you do! I will bookmark you straight away!!
Comment by Allison — June 18, 2008 @ 12:58 pm
Hi Allison,
Thanks for the tip! That’s very interesting.
Regards,
Emily
Comment by Emily — June 18, 2008 @ 9:29 pm
It is so difficult to know which sunscreen is best. All the conflictin information is so confusing. Add to that the growing problem of vitamin D deficiency. Argh!!!
Comment by Andrea — June 28, 2008 @ 6:34 am
Well, I believe UVA protection is best against skin cancer, which is my main concern. The vitamin D thing is worrying though — I’ve heard lack of vitamin D has been correlated to breast cancer, which makes me nervous (though I really haven’t done any research on it, this is really just hearsay). Breast cancer, skin cancer, I hate making the trade off.
Comment by Emily — June 30, 2008 @ 11:16 pm
I’ve read that you only need 10 minutes exposure to the sun per day to be able to make plenty of vitamin D. Also, Naturopathica makes a lovely (though pricey) SPF 17 lavender moisturizer with zinc oxide. I use it on my face, and it doesn’t streak. http://www.naturopathica.com/skincare-moisturizers.html#15002
This is random, but would eating zinc-rich foods help protect from the sun?
And, I read taking zinc supplements isn’t great because it’s not good to have too much heavy metal in the body. Does this also apply to zinc oxide applied topically, I wonder?
Comment by Helen — July 9, 2008 @ 9:57 pm
Hi Helen!
Welcome to my blog! I’m intrigued to hear that you only need 10 minutes exposure to the sun to get enough vitamin D. Maybe I’m getting enough after all!
Ooh — I’ve been tempted by Naturopathica sunscreens before — I shall definitely give them a try sometime in the near future now that you’ve recommended them to me! (I’m very excited by zinc containing sunscreens that don’t streak.)
Gosh, I have no idea if eating zinc rich foods would help protect from the sun. I haven’t heard of any studies of that sort of thing. All the stuff I’ve read just suggested that zinc oxide has a sort of a sunhat effect, so ingesting it probably wouldn’t allow it to work properly, but maybe it has some other benefits? I have no idea.
Actually, you bring up a good point about topically applied zinc oxide. From a rational standpoint, smearing oneself with a metal can’t be that healthy. (Not that smearing oneself with avobenzone or mexoryl can be that healthy either — they haven’t even been around long enough for people to study their long-term effects the way zinc has.) Though smearing oneself with zinc must be far healthier than ingesting too much zinc — a lot less zinc can cross the barrier of your skin to get to your bloodstream than can get from your stomach to your bloodstream. (Unless, of course, you’re using a sunscreen containing nanoparticles of zinc oxide — nanoparticles have been shown to go between cells. To my very limited understanding.)
http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/05/17/MNGFHIT1161.DTL
It’s a fascinating area, isn’t it?
Regards,
Emily
Comment by Emily — July 11, 2008 @ 3:21 pm
whats does uva ray mean
Comment by jessica — September 3, 2008 @ 3:15 pm
Um, a UVA ray is a . . . type of invisible ray of sunlight — it’s in the light we use our eyes to see with. You know how there’s a rainbow of light? Red, orange, yellow, green, blue, violet? Those are actually just the visible wavelengths of light we can see — red has the longest wavelength of the rainbow colors, violet has the shortest. There are many wavelengths in sunlight that have longer wavelenths — those are infrared rays, which we feel as heat, and there are wavelengths of light that have shorter wavelengths — those are ultraviolet rays and X-rays and a bunch of other rays as well. We can’t see infrared rays, ultraviolet rays, or X-rays. “UV” is a shortening of “ultraviolet light” and “A” is a subsector of ultraviolet light. Ultraviolet rays are called “ultra” violet because they have shorter wavelengths than the violet light we can see with our eyes — hence they are “beyond” violet. Each wavelength of light has different properties — the shorter the wavelength generally the more energy it has, which is why the shorter wavelength rays are usually so harmful — X-rays and UV rays are known to cause cancer because they’re so strong. (Though that’s a serious generalization about a complex situation.)
Let me check, the Wikipedia definition of ultraviolet light is:
“Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays. It is named because the spectrum consists of refrangible electromagnetic waves with frequencies higher than those that humans identify as the color violet.”
“UV light is typically found as part of the radiation received by the Earth from the Sun. Most humans are aware of the effects of UV through the painful condition of sunburn. The UV spectrum has many other effects, including both beneficial and damaging changes to human health.”
To my vague recollection, there are 3 types of ultraviolet light — Ultraviolet A (UVA), Ultraviolet B (UVB), and Ultraviolet C (UVC). UVA, in particular, is “long wave” ultraviolet light with a wavelength of 400nanommeters–315nanometers.” (Nanometers are tiny.) In comparison, Ultraviolet B is a “medium wave” and has a “wavelength of 315nm-280nm,” and ultraviolet C has a “wavelength of 280nm – 100nm.”
I hope that helps! It was a bit of a refresher for me as well . . .
Comment by Emily — September 12, 2008 @ 6:55 pm