X-rays cause 700 cases of cancer every year in the UK, around 5700 in the USA, and a total of 18,500 cases overall in 15 developed countries, a new study has found.

Cancer risks per cumulative x-ray exposure range from just 0.6 per cent in Poland and the UK, and up to 3.2 per cent in Japan, the highest. The USA has a cancer risk of 0.9 per cent.

The findings, made by Oxford University, should come as no great surprise. Radiation is a known carcinogen, and medical x-rays represent 14 per cent of total radiation exposure. A study produced back in 1981 confirmed that 0.5 per cent of all cancer deaths in the USA were caused by x-rays.

Despite that early warning, x-rays have been increasingly used, and it's doubtful just how many are necessary. It's been reckoned that 30 per cent of chest x-rays are of no medical benefit, but are carried out as a routine procedure.

Doctors were quick to reassure the public that x-rays are essential, and that there benefit far outweighs any cancer risk. 'We have very strict regulations to make sure we are only giving x-rays and CT examinations to those who need them,' said Prof Adrian Dixon of Addenbrooke's Hospital in Cambridge.

So let's hope that, after these latest findings, they start sticking to them.

(Source: The Lancet, 2004; 363: 345-51).

* To find out more about x-rays and all the other medical tests and procedures, you should be reading the WDDTY Guide to Medical Tests. It explains what they do, how useful (and accurate) they really are, and any dangers associated with them. To order your copy, follow this link: http://www.wddty.co.uk/shop/details.asp?product=16