I have posted on this before: see eg the entry for 24th February 2008 at http://www.users.on.net/~rjfenwickelliott/diary2008.html. Since then there has been more research. Thus Sunscreen abuse for intentional sun exposure by P. Autier published in September 2009 analysed why it is that
melanoma risk is increased when sunscreen is used.
Even the New South Wales police (not universally known for the alacrity of their thinking) are on to the point! More recently, in his blog of a couple of weeks ago, Dr John Briffa commented on the results of the meeting in 2000 of the International Agency for Research on Cancer in Lyon, France, and summarised as follows:
In other words, don’t rely on sunscreens to protect you from melanoma, because they probably won’t, and may actually increase risk. A more recent review concluded that studies link sunscreen use with increased risk of moles, malignant melanoma and basal cell carcinoma.
I have not used sunscreen for 20-odd years, opting to seek shade and wear appropriate clothing when the sun is at its hottest. Because sunscreens can give us a false sense of security, it might be wise to use it sparingly.
I am with Dr Briffa here. Those who research these things have doubted for quite a few years now that sunscreens work to prevent cancer (they do of course to stop you getting sunburned (which is good), and from producing Vitamin D (which is bad – really quite seriously bad) and from getting a tan (which some people like and others don’t). In any event, the association between skin cancer death and sunscreen is much stronger than the association between skin cancer death and sunshine. Those who make a fortune of selling sunscreen and those who just love telling other people what to do are the ones still preaching the old story.
Anyway, most malignant cancers start in the more tucked-away parts of the body, like the groin and the armpits. So, unless you have some very weird ideas of how to go about sunbathing, you have got some serious explaining to do if you want to tell people to use sunscreen.