The warning appeared in American email boxes this spring. Now it is sweeping Britain - and its message is terrifying: normal under-arm antiperspirant is "the leading cause of breast cancer."
The explanation appears logical. Antiperspirants block the discharge of toxins from the armpit. Toxins then build up, causing cell mutation. "Women who apply antiperspirant after shaving increase the risk, because shaving causes almost imperceptible nicks, which give the chemicals entrance into the body," warns the email. "PLEASE pass this along to anyone you care about."
The message speaks to a modern paranoia, and to those of us without medical training, may seem as plausible an explanation as any for the large proportion of breast cancers that remain unexplained. It carries echoes of older fears: most antiperspirants contain aluminium chloride, and the rumours that link aluminium to Alzheimer's disease are well-worn. And if you wonder why you hadn't read about the scare in the mainstream media - well, that just shows how much you know about the awesome power of pharmaceuticals companies to suppress truth when it threatens their vast incomes.
Thankfully, though, it's a load of nonsense, according to both the Cancer Research Campaign and the American Cancer Society. "At the moment there is no evidence to link antiperspirants with breast cancer," says a CRC spokeswoman. "It would be dangerous to worry people until we have some clear evidence." One cancer specialist is more forthright. "It's a bunch of crap," he says.
The email health scare is as infectious as any virus, and it's thriving. Believe everything currently in circulation on email or the web, and you'd be avoiding sun lotion (it makes you go blind), washing your cola can before drinking from it (they're caked in lethal rat's urine, after all) and not using saucepan scourers (which, it transpires, contain Agent Orange, as used to destroy vast swathes of Vietnam).
Actually, there is genuine research going on into a possible link between underarm sprays and breast cancer - not that you'd know it from reading the email. Dr Philippa Darbre, a biotechnologist from Reading university, is examining a possible link between breast cancer and parabens, a preservative found in many deodorants, which has been shown in other contexts to simulate the behaviour of oestrogen, the female hormone involved in most cases of the cancer. But the work is speculative and, Dr Darbre stresses, the hypothesis bears no resemblance to the explanation presented in the email as undisputed fact.
A recent survey found 29% of people in the US use the net for health advice. There are no figures available for Britain, but anecdotal evidence suggests a rapidly increasing number of people visiting their GPs with sheaves of internet search results in hand. But online advice can be unreliable: modern-day mountebanks have set up websites hawking every thing from Viagra to human growth hormone and a study at Heidelburg university in Germany, published in the Lancet, found that more than 10% of online doctors gave potentially dangerous misinformation.
Doctors Gunther Eysenbach and Thomas Diepgen invented a patient suffering from herpes who was also on medication following a kidney replacement. One doctor recommended "two apples a day"; another offered to sell a "red clover and dandelion" potion.
But commercially motivated charlatans must compete with the fact that numerous websites are fast becoming well-recognised repositories of authoritative news and information. Forwarded emails have a special potency, however: within hours, they can replicate exponentially around the globe, leaving the identity of their authors lost in the mists of cyberspace - and yet the copy that you, personally, receive is likely to have come from someone you know.
Many such panic-inducing alerts play on fears that already linger unarticulated in the collective consciousness, mixing a small amount of fact with lashings of paranoia. Cancer recurs again and again - as in an email spotted a year ago (carrying the subject line "SHAMPOO ALERT!!! MUST READ!!!") which warned that sodium laureth sulphate, found in many shampoos, but also "used to clean garage floors", is a carcinogen. (It's not thought to be; and the industrial detergent is another compound, called sodium lauryl sulphate.)
Another warning masterfully combines two genuine and frightening but low-incidence health risks - toxic shock syndrome and asbestosis - in a message claiming that brand-name tampons are made with asbestos to promote bleeding. Yet another constructs an ingenious but fallacious argument to explain why fluorescent lights rob your body of vitamins as you work.
Other scares recapitulate urban legends and old wives' tales notable above all for their narrative ingenuity. Heard the one about the gang initiation ritual which involves hiding HIV-infected syringes in phonecard slots? Or - in a twist on the same legend - coating payphone handsets in a deadly mixture of LSD and strychnine? The one about the deadly south American blush spider which migrated to the northern hemisphere via airline toilet facilities and killed several people? Or the many tales relating visits to fast-food outlets that ended with a mouthful of mouse flesh, razor blades, or cockroach eggs? They are all hoaxes - at least according to David Emery, an urban legends specialist at About.com, a web-based guide to reliable online information.
But when an emailed warning is not quite so obviously ridiculous, how do you separate fact from fiction? "The very fact that it comes as an email and tells you to spread it to everyone else is a sign that it's extremely likely to be a hoax," says Stephen Barrett MD, proprietor of Quackwatch, a website which monitors and exposes shoddy medical information. "If it were true, you wouldn't be finding out by email. Some of the content would be so significant that it would make headlines everywhere - and it wouldn't take more than a few minutes for CNN to have it all over the world."
Such justifications are unlikely to appease the more ardent conspiracy theorists. But, says Barrett, there are other clues: lack of references, lack of clear authorship, over-energetic deployment of exclamation marks, vagueness about the names of allegedly dangerous chemicals, and confused arguments.
On the latter point, the antiperspirant email is a classic case: the (unnamed) author cannot decide whether the danger lies in the way the spray blocks the release of naturally produced toxins (again unnamed) or in the toxic effects of the spray itself if it enters the body. It claims men are less likely than women to develop breast cancer from underarm sprays because armpit hair stops it reaching the skin - ignoring the fact that the main reason the cancer strikes men 100 times less often is that they possess 100 times less breast tissue.
Plans are now being drawn up to introduce a basic level of quality control for web-based health advice, which may go some way to discrediting the deluge of health scare emails. Following several US lawsuits against online pharmacies, two commercial health websites - Drkoop.com and Medscape - have announced initiatives to banish dangerous advice and separate disinterested guidance from promotional material.
The British Medical Association supports a similar UK plan, and it hopes that the new National Institute for Clinical Excellence will take the lead. But it is a short step from regulation to censorship, and some see in these moves an implicit threat to the values that the internet purports to embody.
Ultimately, Barrett argues, the internet will be good for our health. "If someone makes a TV show on, say, homeopathy, they're never going to conclude that it's a fake. Many of these topics never get really critical scrutiny in the profit-driven media because they don't want to offend anybody. The internet provides the only major way to put across information that is not tied to commercial interests. And that's very important."
Useful links:
Health websites you can trust (probably)
Medicine Plus
Consumer-friendly version of the health professional's database. Medical World Search
Medical search engine that claims to link only to reputable health sites. Health Scout
Vast site with reliable health content from around the web.
Online health hoaxes and 'netiore'
Quackwatch
Extensive database of health hoaxes and dodgy doctors.
About.com's urban legends pages
David Emery's constantly updated catalogue of hoaxes and frauds.
Snopes.com
Huge catalogue of urban myths
