It seems myths are tough to kill. And there are fewer subjects which generate as many theories and myths as cancer. These flimsy pieces of misinformation can give false concern, spread fear and, in some cases, raise false hopes among cancer patients.
To mark World Cancer Day, which occurred on Monday, the Union for International Cancer Control has taken a stand against misinformation, declaring that busting cancer myths would be its theme for 2013.
Here at the Cancer Council Western Australia, the folk who answer our Cancer Helpline report that the favourite myths include that cancer is caused by hair dyes, cosmetics and deodorant sprays, and that power- lines and mobile phones cause brain cancers or leukaemia. And there's the old favourite: cancer is caused by fluoride in water.
Well, none of these is true or proved. But let's tackle them one by one and find out where the myth started.
In the very early days of hair dyes, charcoal or similar products were the main ingredient for blackening the hair of those (mostly women) keen to avoid the ageing look of grey hair.
The tars and similar by-products found in the charcoal were - like the tar in tobacco smoke - carcinogenic. But now the commercial hair dye industry has become an international, multimillion-dollar concern, and the chemicals used are far better researched and scrutinised. They have been shown to be safe.
The old tar-based products have long been phased out. Having had that history, at least there is some reason as to how the story started - even if it is no longer accurate.
Of course the term "cosmetics" covers an enormous variety of substances, products and chemicals. Again, commercially available cosmetics undergo close testing and scrutiny in Australia.
They are treated as industrial chemicals and assessed by the National Industrial Chemicals Notification and Assessment Scheme, a part of the Federal Department of Health and Ageing.
With all the claims made by cosmetic companies, implying - if not directly claiming - eternal youth and beauty, perhaps it is not surprising some people are sceptical. And like hair dye, there is some history of unsafe ingredients, most notably the use of mercury and lead in the early days. Most recently, phthalates, paraben and AHA (Alpha Hydroxy Acid) have been used.
However, ongoing research seems to be finding no link between regular use of mainstream cosmetics and cancer risk. But the research will no doubt continue - as it should.
Deodorant sprays, roll-ons, anti-perspirants and other body odour control products have attracted attention based on the theory that they cause breast cancer. The proximity of the armpit and breast tissue means some breast tissue, and even breast cancer tissue, has been found to contain deodorant ingredients, such as aluminium. This has led some to add one and one and come up with "cancer causer".
A summary of the evidence published in 2004 found "there is no reliable evidence that underarm cosmetics use increases breast cancer risk in humans". Even so, one researcher at Reading University in the UK persists in conducting research into this area. Yet, neither she - nor any other researcher - has demonstrated a link between deodorants and cancer.
The researcher persists in warning that if she does, we may be able to prevent breast cancer in the future. That is true but first proving the link is necessary - and that hasn't happened yet. Nor does it seem likely to.
The radio frequency waves and electronic fields linked to powerlines and mobile phones have long been suspected of contributing to cancer risk. Many studies have been mounted to determine if the risk is real. The summary of the story so far is that there remains no convincing evidence linking spending time near powerlines (either living or working near them) or the heavy use of mobile phones with increased cancer risk.
Neither is easy to study and mobile phone technology remains fairly new. Long-term studies are underway to monitor the prospect that mobile phone use causes cancer. To date, however, most in the field would agree that the evidence needed to prove a link does not exist.
Fluoride in drinking water has been an enormous benefit to reducing tooth decay in children.
The suggestion fluoridated drinking water causes cancer has been perpetuated for many years, perhaps by those opposed to fluoridation of water.
Despite rigorous research no evidence has been found linking fluoride ingested through drinking tap water to any type of cancer.
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