Tanning

California bans minors from using tanning beds

California just banned the use of tanning beds by minors.  What's next, shutting down the beaches on sunny days?

I'm exaggerating a little bit.  Tanning beds don't emit the same UV wavelength and intensity as natural sunlight -- so I suppose there's a technocratic public health case to be made -- but at the same time, in a sunny state like California (well, Southern California), there are plenty of opportunities to burn yourself naturally.

But it's far from clear that tanning bed usage is a primary driver in the rise in melanoma and non-melanoma skin cancer.  I have been searching the website of Ted Leiu, the State Senator sponsoring the legislation, for the scientific papers that make him so confident:

  • "If everyone knew the true dangers of tanning beds, they’d be shocked."
  • “Other scientific research has shown conclusively that use of tanning beds causes skin cancer, and the younger kids are when they start using tanning beds, the greater the cumulative damage to their skin and the more likely they are to die of skin cancer.”

After much digging, I found a frequently cited statistic ("those who use tanning beds before age 35 increase their lifetime risk of melanoma by 75 percent") pointed back to this meta-study: "The association of use of sunbeds with cutaneous malignant melanoma and other skin cancers: A systematic review".

This is from the abstract:

"Based on 19 informative studies, ever-use of sunbeds was positively associated with melanoma (summary relative risk, 1.15; 95% CI, 1.00–1.31), although there was no consistent evidence of a dose–response relationship. First exposure to sunbeds before 35 years of age significantly increased the risk of melanoma, based on 7 informative studies (summary relative risk, 1.75; 95% CI, 1.35–2.26)."

So ever-use of tanning beds based on 19 studies showed a minimal increased risk (15%), with no dose-response relationship -- which is rather odd, given that you would expect more tanning sessions to lead to a greater incidence of melanoma, right?  In the group of 7 studies that looked at age of first exposure, the relative risk was 75% higher.

Sounds big, doesn't it?

Not when you start looking at other risk factors of melanoma (which they didn't do in the meta-study).  I blogged last year about a new paper that tied melanoma to tanning bed usage.  In that study, the risk factor for ever-use of tanning beds was 74% (higher than the 15% in the meta-study just mentioned).   But this 74% higher risk from tanning beds was exceeded by blonde hair (117%) and dwarfed by red hair (253%), very fair skin (450%), and having moles (1,281%).

That's a huge flaw in this research -- it doesn't focus on the most important risk factors to help us understand the phenomenon of skin cancer, it is out to prove a point about a pet cause: tanning beds.

Another flaw is that few of these studies ever mention any of the benefits of sun or -- heaven forbid -- tanning salons.  Shouldn't California at least go through a cost-benefit analysis?  Are there other types of cancer that might be decreasing with UV exposure?  Maybe so, maybe not -- but don't you think we should look?

Furthermore, the law applies equally to fair-skinned and dark-skinned people (as laws should), but this completely neglects that fact that the cost-benefit trade-off will likely vary substantially based on skin color.  Black adolescents are one of the groups with the highest vitamin D deficiencies in the country (need citation) and black people have dramatically lower rates of skin cancer -- does this ban benefit them?  That said, black people don't go to tanning salons as much as white people do -- but that's not to say they wouldn't benefit from greater UV exposure.

Here's a brilliant solution for our omniscient nanny-state: white adolescents should be banned from tanning salons, but black adolescents should be forced to go to tanning salons.

You see how ridiculous this is?  It's what happens when do-gooder politicians marshal bad (or incomplete) science to attack unpopular, "sinful", or "frivolous" industries.  I understand that this is focused on minors, but states and countries are getting more and more aggressive with these sorts of things.

All this neglects the broader point that people should have the choice to live as they see fit, as long as they aren't harming anyone else.

Media hysteria on tanning beds and melanoma

A recent study on tanning beds and melanoma has been making the rounds: "Indoor Tanning and Risk of Melanoma: A Case-Control Study in a Highly Exposed Population".  The WSJ, Time, NPR, and USA Today have all covered it.  The big statistic that everyone is throwing around is that "people who tanned indoors had a 74% higher chance of developing melanoma than those who hadn’t."  Note that the reason this paper is such a big deal is because there has never been strong evidence that using tanning beds caused melanoma.

Well, I had the great pleasure of meeting Dr. Michael Holick today, and we discussed this very paper.  You can view the full text here.  Let's go the actual science and see what it says.

The 74% number comes from Table 3, second row, in the last column called multivariate adjusted OR (odds ratio).  You'll see a 1.74 (hence, 74% more likely), plus a confidence interval.  (This interval, or error bounds, simply indicates that if you ran this experiment 100 times, 95% of the time you'd expect this value to fall between 1.42 and 2.14.)  The odds ratio for hours spent in a tanning bed increases to 3.18 (218% more likely) with duration of tanning bed use.

Well, from all the media hysteria, you'd expect that tanning beds would be the primary risk factor uncovered in the study.  And you'd be wrong.  Flip up to Table 2 and let's take a look at the odds ratios of other factors.

Hair Color

What color is your hair?  Redheads have an OR of 3.53 -- which means red heads are 253% more likely to get melanoma.  Compare that to the 74% number associated with ever having gone to the tanning salon.  And even blondes are 117% more likely (2.17 OR).  Having blonde hair or red hair has more to do with your risk of melanoma than whether you've ever gone to the tanning salon.  

Skin Color

Having very fair skin increases your chances of melanoma by a whopping 450% (5.50 OR).  Fair skin is 263% more likely, and even light olive skin is more important than having gone to the tanning salon.

Moles 

Moles!!!  If you have a bunch of moles you're 1,281% more likely to get melanoma.  Having lots of moles is nearly 20X more important than whether you've gone to a tanning salon.

Lifetime Sun Exposure

Three measure of sun exposure show that high lifetime sun exposure decreases risk of melanoma (ORs of .85, .95, and .84).

Sun Burns

Sun burns, on the other hand, do increase your risk of melanoma, comparable to tanning salon usage.  

Mean Lifetime Sunscreen Use

Get this -- THE SAME STUDY THAT CONNECTS TANNING BEDS WITH MELANOMA ALSO CONCLUDES THAT HIGHER SUNSCREEN USAGE INCREASES YOUR RISK OF MELANOMA.  Medium or High mean lifetime sunscreen usage increases your chances of getting melanoma by about 30%.  But somehow "Sunscreen usage causes melanoma" is a less catchy headline than "Tanning beds cause melanoma".

My point is not that there are no risks to tanning beds.  My point is that the biggest risk factors for melanoma are NOT tanning bed usage and are NOT sun exposure.  It's having moles.  And red hair or blonde hair.  And fair skin.

So how about we do some science that actually tries to understand what's going on, instead of attention-grabbing headlines that confuse and scare people. 

Assorted links

1. Tanning is associated with optimal Vitamin D status and higher bone mineral density.  (NOTE: But as one commenter pointed out, most tanning salons try to sell you UVA, when this paper is talking about UVB.  Don't rush to the solarium.)  And this:

"There is increased concern about skin cancer, which has created a fear of causative sunlight exposure (9 –12). Melanoma is the most serious form of skin cancer. It should be recognized that most melanomas occur in areas that are not exposed to the sun (13) and that it is the number of lifetime sunburn experiences, the number of moles, and red hair that increase the risk of this deadly disease (12)."

2. Melissa McEwen's poetic description of learning to hunt, dress, butcher, and eat deer

"We carved the body cavity through and through, leaving bare ribs skinless so the light could shine through. The digestive system we left for the vultures, as it belongs to them. I read recently about one of the earliest religious sites, Göbekli Tepe, a marvel considering that hunter-gatherers had no cities, but they bothered to build this temple carved with vultures, lions, and other predators of humans dead...and alive. Some theorize that the hunter-gatherers left their dead here to be eaten by these fierce flesh eating creatures. The word for this is "excarnate," which is very beautiful to me, the idea of sharing your body with other carnivores. I think of then as a time when none owned another, except in death when it was an honor to be consumed and melded with others."

3. Tyler Cowen responds to fears that food markets will be turbulent in years ahead

4. Reasons for optimism: perch in downtown Milwaukee and tilapia in Colorado

5. I'll be in DC this weekend, and I'm looking forward to the well-regarded Mitsitam Cafe at the National Museum of the American Indian. 

"Mitsitam (pronounced Mit-see-tum) means “let's eat” in the Piscataway and Delaware language. The 350-seat restaurant is essentially an extension of the museum, specializing in authentic Native American cuisine. The seasonal menu changes on each equinox and solstice and is divided among five Native American regions: Northern Woodlands, Northwest Coast, Great Plains, Meso America and South America."

Why I went to the tanning salon this winter

Part of paleo is about experimentation and discovery.  This winter I started experimenting with going to the solarium....better known as the tanning salon.  That's right, I went to the tanning salon.  Really courting medical controversy here.  So here's why I went.

My initial reason was to get a base layer and avoid a sunburn in Mexico.  I had signed up for the MovNat course in Mexico in mid-January, and it seemed prudent to get a base layer to make it less likely I would burn in Mexico.  Sun burns are what cause the most damage to your skin and most increase your chances of skin cancer.  My sessions were purposefully short duration (<7 minutes) and low intensity, and so I needed to do a few of them before I got a noticeable tan.

Healthy Vitamin D levels decrease your overall chances of getting cancer.  My reading of the literature indicated that 1) it's extremely difficult to get sufficient Vitamin D from food and even supplements, 2) the deadly forms of skin cancer are more rare than generally thought, 3) they don't seem connected to sun exposure per se (sun burns are the more likely culprit), and 4) and your higher chances of getting skin cancer are far outweighed by the cancers you avoid by getting enough Vitamin D.  Use of a tanning bed -- with the right UV frequencies -- has also been shown to increase Vitamin D levels.  As for a few more wrinkles as I get older, that seems to be true, but I just don't care.  For an excellent overview of what we know about the sun, Vitamin D, and cancer, watch this video by Dr. Michael Holick at BU.  (He doesn't endorse tanning.)

My mood improved immediately.  I don't know what to say, it just did away with the winter doldrums.  The first time I went was in early January in New York City.

Now, would it better to get moderate sun exposure?  Yes.  Would it be better to have a UV solution in winter that mimicked natural sun light? Yes. Is it a good idea to go to the tanning salon to get burnt to a crisp in 10 minutes?  No, of course not. 

Who could benefit most from going to the solarium?  People with dark skin.  Dark-skinned people are adapted for an equatorial environment with enormously high sun exposure all year round.  It's as if they are wearing high SPF skin block all the time.  They need more sun to generate the same amount of Vitamin D as a fair-skinner person.  So black people who live in high latitudes or who live near the equator but are covered up all the time are particularly at risk.  Bad news for burqas -- blocking out the sun is causing rickets and osteoporosis in Middle Eastern women.  From the abstract:  

"Despite ample sunshine, the Middle East (15°-36°N) and Africa (35°S-37°N), register the highest rates of rickets worldwide. This is in large part explained by limited sun exposure due to cultural practices and prolonged breast feeding without vitamin D supplementation in the Middle East, and by dark skin colour and calcium deficiency, rather than vitamin D deficiency, in several countries in Africa. Both regions also have a high prevalence for hypovitaminosis D, the latency disease for osteoporosis, and the main focus of this discussion."
 
Wouldn't it be ironic if the first tax enacted as part of the health care plan was actually counter-productive?  I'd be willing to wager that the 10% tax on tanning salons caused a net decrease in the health of African-Americans.  (Not sure how many actually go.)
 
Anyhow, here's to a little experimentation.  I'm sure I'll have a few more posts on this taboo subject in the days to come.

 

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