I see that Cecil’s brief discussion of sunscreen has been run again. Since that summer approacheth, and skin cancer rates continue to rise, he really ought to amend that column in at least one significant way:
Titanium dioxide and other mechanical sun blocks no longer have to be opaque, so you can get their protection without looking like a clown. Consider the following info:
UVA rays are the sun’s silent killers. You don’t feel them but they are the primary cause of skin cancer and wrinkles. (UVA rays also penetrate through clear glass windows.)
SPF is crucial, but it is only a measurement regarding sunburn (UVB) rays. There are no numbers to tell you about protection from UVA radiation. Most sunscreens now claim to have both UVA and UVB protection, but only offer protection from about 20% of UVA rays. For real UVA protection you have to check the active ingredient list to see if it contains either zinc oxide, titanium dioxide, avobenzone (which may also be listed as Parsol 1789 or butyl methoxydibenzoylmethane), or Mexoryl SX outside of the US. If one of those isn’t part of active ingredient listing (it doesn’t count if it is just part of the regular ingredients) you will not be getting adequate UVA protection.
Skin cancer rates have been increasing ever since sunblock was introduced, which baffled doctors. Researchers are now suggesting that it’s because people stay out in the sun longer than they used to! People think that if they’re not getting a sunburn, then they’re not increasing their risk of skin cancer. For some people, this is a fatal mistake.
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Cecil’s column can be found on-line at the link provided by bibliophage.
Checking in from the skin cancer capital of the world, Queensland, Australia! (a perfect confluence of an outdoor lifestyle, the tropics and a whole load of imported white folks).
Such is the scepticism regarding the effectiveness of sunscreen that the health authorities here now do not recommend their usage, other than as backup, and recommend that you wear long clothing and a hat at all times. So now you commonly see people at the beach wearing a “sunshirt” (a long sleeved close fitting dark coloured lycra top) even when swimming.
And there is a move to SPF rate clothing, as well, because many light coloured shirts are not as sun proof as is generally assumed.
Minor nitpick. The rating system for textiles and clothing referred to by Princhester, is called UPF, not SPF. The testing procedures are different, with different test endpoints. SPFs are measured on human skin, UPFs are measured using a machine. The results are similar, but not necessarily identical.
And then there’s this, which made me go “Huh?” in a really major way.
You mean, for the last 50,000 years or so, all those Africans and Aborigines and Andaman Islanders have all been suffering from rickets? How could homo sapiens’ DNA overlook something like that?
Or is it just a slanted, stupid interpretation of the results of a very limited study, combined with the media’s urgent need to provide catchy sound bites?
I find the factoid “dark skinned people’s skin can’t manufacture Vitamin D” posted widely, but I can’t find the actual study on the Web, offhand, so I’m going over to GQ to ask.
How could homo sapiens’ DNA overlook something like that?