Just in time to drive parents into a panic for the rest of the summer, the New York Times has a big article about sunscreen:
Dr. [James] Spencer [a dermatologist in Florida] said that an S.P.F. 15 product screens about 94 percent of UVB rays while an S.P.F. 30 product screens 97 percent. Manufacturers determine the S.P.F. by dividing how many minutes it takes lab volunteers to burn wearing a thick layer of the product by the minutes they take to burn without the product.
But people rarely get the level of S.P.F. listed because labels do not explain how much to use, said Dr. Vincent A. DeLeo, chairman of dermatology at St. Luke's-Roosevelt Hospital Center in Manhattan.
"Sunscreen is tested at 2 milligrams per square centimeter of skin, which means you should be using two ounces each time to cover your whole body," Dr. DeLeo said. "But for most people an eight-ounce bottle lasts the whole summer."
(How muuch must it suck to be the sunscreen tester? "Mornin', Bob, ready to be fried again?")
As a pasty Northern European (Polish-Irish-- "All the winners of Europe," as a friend put it), I'm of two minds about this.
On the one hand, sunscreen is a Good Thing, because there are few things that suck more than having your whole skin just hurt. I don't burn nearly as badly as my sister does-- she tends to blister, and once spent the last couple days of a vacation in Mexico lying in a dark room with cold damp cloths on her shoulders-- but I am true to my northern heritage, and turn bright red after a while in the sun. And I've had some sunburns that made just moving around agonizing-- these days, I usually put about an ounce of sunscreen on the backs of my knees, because Jesus, that hurt.
On the other hand, though, this story sort of reinforces the common image of scientists and doctors as humorless scolds. Take, for example, the closing admonition:
Dr. Green in Australia said the best way to prevent skin cancer is to stay out of the sun during peak hours and wear sun-protective clothing. But Dr. Halpern said you can't keep Americans wrapped up.
"There is only a small subset of American society that is willing to wear long-sleeved shirts and wide-brimmed -- defined as four inches wide -- hats on a sunny day at the beach," he said. "Until we can get that behavior, the next best thing is sunscreen. Put on two coats, so you won't miss any spots."
You can almost picture this being said while shaking a cane at frolicking teenagers from the shelter of a rickety porch. "You damn kids, with your running about enjoying yourselves! Get off of my beach!"
Really, scolding people is the wrong way to go about this. If you want to get Americans to wear sunscreen and stay out of the mid-day sun, the thing to do is to go after celebities-- as long as being tan is considered glamorous and sexy, there will be lots of people lying around in the sun with no skin protection. If you get movies and magazines and gossip shows to start hyping fish-belly white as the hot new look, you'll empty the beaches right out.
And you'll be a hero to the Polish-Irish forever.
As a pasty Northern European
My wife prefers "melanin challenged" for me.
I really recommend the broad brimmed hat, it works and it really helps make you look like a physicist. I also suggest wearing dark socks pulled up to the knees with your shorts.
On the flip side, this is a (minor) public health issue. Skin cancer is a problem, and the more time you spend getting fried, the worse is could be. There is a reason Australia and New Zealand have some of the worst rates in the world, pale people and lots of sun do not mix.
This is eerily timely. I just had a conversation with my sister about this yesterday. We are also Polish and Irish plus Dutch, English, French, German, Ukrainian.... etc. - pasty whites all the way. I have been admonishing her for not using sunscreen since she always appears so tanned but yesterday she shot back that she always uses SPF 15 or 30 and tans anyway. Now, personally, I never measure how much I put on myself (I'm a theorist, after all) but if anything I suffer from over indulging in the sunscreen. I put gobs and gobs on and I do frequently wear a wide-brimmed Aussie-like (but for other reasons - it fits my persona as a rugged outdoors type). I never burn as a result, but my arms do get moderately tanned. A bigger problem here in Maine and New Hampshire is that one has to learn the fine art of applying both sunscreen and bugspray since it only works properly when done a specific way: sunscreen first, allowing several minutes for it to soak in, then bugspray. And my children's pediatrician said the only effective bug repellent is something that has a minimum of 20% DEET (apparently they know this from testing - yes, after frying in a sunscreen test, you can get eaten alive in a bugspray test).
Having my Irish-American father's melanin levels, I tend to put on lots of sunscreen. The bottle says apply liberally and I follow directions. But I am always getting weird looks from friends who then make comments about my "bathing" in the stuff. I usually have a long sleeve cover-up handy when out of the water and a hat. (I've had my hats made fun of while doing fieldwork. Have you ever burned your scalp - OW!). I don't like to sunburn. I almost always wear long sleeves, long pants (tucked into my socks, no less), and a hat in the field but that is as much for the mosquitos, ticks, posion ivy, and thorns, as for the sun. (Aren't you glad you choose physics over geology or biology?)
I've never burned the back of my knees but a couple of summers ago I feel asleep on my stomach and apparently I'd missed two spots on at the top of my thighs (I was sitting down while slathering up). I was reminded of my mistake everytime I sat down or stood up for a week.
Sunscreen toxicity, mutagenicity, carcinogenicity, and reproductive hazards are tested by the book - sunshine exposure is not a protocol. Psoralins are mostly harmless away from UV light. Given UV light, skin contaminated with psoralins will inflame, ulcerate, and eschar practically before your eyes.
Hydroxybenzotriazoles are not used as suncreens. We did tox testing of human-implantable intraocular lens UV absorbers. Cells happily grew over neat insoluble hydroxybenzotriazoles in preference to Petri dish surface. The FDA won't clear for human use unless hazards are quantified, hence Alice in Wonderland,
Uncle Al, "We have better than zero toxicity. Cells like the new UV absorbers!"
Management, "Could you make some toxic ones so we can dope the controls down to zero effect?"
I'm with you on the anti-humorless scold issue. Much of the time, when scientists and doctors are admonishing the public on what to do, it's excessive anyway. So not only are they off-putting, they're not entirely worth listening to.
Long sleeved shirts and wide-brimmed hats? One coat of SPF 45 lasts me well over the recommended 80 minutes, and I can put it on when I arrive at the beach, not 30 minutes before hand as the bottle states. Granted, I'm only concerned about burning -- I don't mind a little tan. Scotch-English pale, by the way.
And who actually needs to drink eight glasses of water a day?
What I want is sunscreen that goes on colored -- purple, maybe -- but dries clear. I usually put on plenty, but sometimes I miss spots, and end up with odd little geometries of burned skin.
Johan, I've seen sunscreen that does that. It's marketed for kids. At least it was a couple of years ago.
"If you get movies and magazines and gossip shows to start hyping fish-belly white as the hot new look, you'll empty the beaches right out.
And you'll be a hero to the Polish-Irish forever."
And the Scots-German!!
Oh, and don't forget the tops of your ears and feet. I was at a parade in Maine yesterday, and neglected both of those areas. Today I can't wear shoes or glasses at work-- it really limits the public interaction.
I work in the U.S. city that was recently rated the most un-aware of sunburn hazards in the nation, so I wish our local papers would follow the NYT example.
I don't really think scientists are seen as scolds by most people. (Humorless, yes, unfortunately and undeservedly - if they read ScienceBlogs they'd find out otherwise.) In fact some people look on scientists more as skeptics of health hazards.
Myself, I get very tired of journalists when they go on a health tear. The inevitable shocked and scandalized revelations that humans live among *gasp* Gazillions Of Germs! (oh noes!!!11!) is usually a waste of scarce broadcast time or newsprint and contains little of practical use. For gosh sakes, humans evolved among germs. We need germs in our guts to help us process what we eat. I even recall a statistic (somewhere in my archives of interesting Science Daily articles) that our body is probably more microbial by weight than it is human.
Anyway, I'm ranting. And sunscreen is good, but I have no intention of buying those newfangled UV-blocking clothes, not at current prices.
"...go after celebities-- as long as being tan is considered glamorous and sexy, there will be lots of people lying around in the sun with no skin protection."
I am willing to bet that many (most?) of the glitterati are currently indulging in spray-on tans. Likely, that isn't advertised. For the folks with the bucks to indulge in the professional process of exfoliate and spray, the year 'round tan need not equal skin cancer. Of course, it takes some effort to maintain it, but likely it's just in the schedule along with hair stylst appointments and bikini waxes.
Re: tourettist, I have a reference that says that there are approximately 10 times more bacteria in our guts than there are total human cells in our bodies:
Cynthia L. Sears, "A dynamic partnership: Celebrating our gut flora," Anaerobe v. 11, p. 247 (2005).
Another article on the same topic:
Lora V. Hooper and Jeffrey I. Gordon, "Commensal Host-Bacterial Relationships in the Gut," Science v. 292, p. 1115 (2001).