Sir, - Dr William Reville's article on "Cancer: cause and prevention" (June 1st) is in my opinion far too sweeping and general in its arguments, backed by misleading evidence.
Firstly, most research to date agrees that it is next to impossible to ascertain that a particular carcinogen caused a particular person's cancer. Otherwise such carcinogens as dioxins (a grade A carcinogen by WHO classification) would have been banned years ago.
Secondly, he refers to a colleague remarking on how many people he knows who have cancer. It is not specified, but one would presume the colleague lives in Ireland. Why, in that case, is Dr Reville using US figures to support his arguments? Focusing on the number of deaths from cancer is misleading. For example, between 1973 and 1991 in the US, childhood cancers increased by 10.2 per cent especially leukemia and tumours, though death rates went down. Better treatment has helped prevent deaths, but do we really wish such illnesses on our children? What is causing the increase?
I believe Dr Reville describes a measure of toxicity known as "the dose is the poison". Evidence now shows that this approach may be outmoded. Very low doses of carcinogens over prolonged periods can cause cancer as well. Certain chemicals not directly carcinogenic in themselves can weaken human cells, making it easier for milder carcinogens to do damage. True account is not taken of the combined affect of many chemicals in our environment. The most conservative estimates of cancer deaths from environmental pollution in the US is two per cent. This is 10,940 people each year, more than the number of women who die each year from hereditary breast cancer and more than three times the number of smokers estimated to die each year of lung cancer.
Finally, Dr Reville refers to prevention being better than cure. Quite right. We can all stop smoking, eat better and exercise more. However, we have no choice with environmental pollution. How can we avoid the emissions from the factory, the traffic fumes in Dublin (one of the worst in Europe), the herbicides and pesticides on the food we eat (apparently the warning notice on a popular brand of glyphosate makes horrifying reading). This is, as far as I'm concerned, a form of legalised poisoning. Whatever happened to our human right to a clean, healthy and safe environment? - Yours, etc., Jennifer Wann,
Stoneybatter,
Dublin 7.