Ero's claim is based on a study detailed in a book, Dressed To Kill (1995, Avery Publishing). In it, the authors, husband-and-wife team Syd and Soma Singer, argued that bras with underwires squeeze breasts until they can't drain lymph. A clear fluid that moves through our arteries and tissues, lymph is laden with cancer-causing toxins that we all absorb from the environment. Over time, says the book, these toxins cause breast cancer.

Alas for the Singers, experts have roundly dismissed this cancer theory. Despite numerous studies since the 18th century, lymphatic physiology is not completely understood. Nevertheless, the research on which Dressed To Kill is based, is flawed.

We do know that arteries carry fresh blood to all parts of the body, breasts included, while used blood leaves the breasts through veins and is pumped back to the lungs to be refreshed.

The arteries also bring lymph, which then leaves the bloodstream to circulate through tissues, cleansing them. Next, fine vessels called lymphatics collect the used lymph to drain it back into the body's central drainage system. Along the lymphatics, there are stations, or nodes, which filter out and trap bugs, cancer cells and toxins.

Think of arteries as two-lane highways bringing oxygen and nutrients to the breasts, and veins as one-lane highways taking used blood away, with lymphatics forming another one-lane highway channelling lymph away. In short, two similar lanes in, two different lanes out. Whereas the heart pumps blood through the arteries and veins, lymph flows along the lymphatics passively when their surrounding tissues move.

Whence came the Singers' ideas about a bra-lymph connection?

Women in poorer countries generally go bra-less, the Singers noted, as they have done for millennia. The couple reasoned that natural breast movements that occur with every step taken give bra-less women a healthy breast lymphatic circulation - until bras immobilise and constrict it. For example, while Australian aboriginal women have virtually no breast cancer - they aren't assimilated into the mainstream white culture - Maori women in New Zealand, who are westernised bra-wearers, have high breast cancer rates.

To substantiate their postulate, the Singers interviewed some 4,730 American women. They found that women who wore bras for 24 hours daily were 125 times more likely to have breast cancer than those who went bra-less, 113 times more often if they wore the bra for 12 hours each day.

That's a striking discovery - if true. But there are a couple of problems.

First, there are no peer-reviewed studies that report a bra-cancer association, or that bras cause toxins to accumulate in the breasts.

Second, the Singer study did not exclude other risk factors as good studies should. Their sample was a biased one - all Caucasian, mostly 'medium income', aged 30 to 79 - half of whom had had breast cancer. This reason, among others, made it unsuitable for publication in reputable journals.

If you have a startling hypothesis, you need to build up a body of work by first publishing in reputable journals because publication signals that your research is rigorous and credible to your peers. If a consensus forms that you are on the right track, you might then publish a book about it, citing chapter and verse from your own work or the work of others.

Instead, the Singers fired off what they called their 'explosive' survey findings to the most prestigious cancer research institutes. None responded. The reason, the Singers surmised, was that the lingerie business, like the cancer business, was huge, so vested interests were stacked against them.

Third, a controversial hypothesis must withstand testing. From 2001, the Singers say, they have been comparing Fijian women, half of whom wear bras and half of whom don't. While both groups live in the same environment and eat the same diet, the bra-wearers get breast cancer at the same rates as US women do, while bra-less Fijian women have almost no breast cancer.

If true, this would be strongly supportive evidence - but it has only been issued as press releases and hasn't been published in respected journals.

The Singers, who have no bona fide academic appointments, solicit - on the Internet - financial contributions to fund their research, which they conduct from their 'institute', a 27ha farm in Hawaii.

Their supporters, even if they grant that their research methods aren't up to scratch, could still argue that there is merit to their bra-squeezed lymph argument itself.

The Singers say that 'because lymphatic vessels are very thin, they are extremely sensitive to pressure and are easily compressed'. Yes, tight bras with underwires do leave red marks and creases on the skin so they might impede the set of superficial lymphatics that drains lymph from the breast skin and the other set that drains the nipples.

However, the breast has a third and deeper set of lymphatics that drains deep breast tissues. This is the very set involved, if breast cancer spreads, that is removed during cancer surgery. But it is too deep for bras to impinge on, so its lymph should move around as the breasts move inside a bra - except, perhaps, for masochists who wear lycra bras so unimaginably tight they hurt.

Nevertheless, Ero's tagline 'Stop Wearing Bras' does make sense. It is a myth foisted on women that bras keep the breasts perky, because all breasts must eventually sag with age as milk glands are replaced by fat.

There's just no good reason to wear a bra: If modesty is a concern, loose camisoles will do fine.

Sisters, it's bra-burning time.