Mobile phones have no effect at all on the risk of cancer, the largest and longest-running investigation yet conducted has found.

A study that has followed 420,000 mobile phone users in Denmark, for up to 21 years, has comprehensively debunked the common fear of a link to cancer, and shows that mobile phone users have the same chance of developing the disease as the general population.

The very large number of people involved in the research and the exceptionally long periods over which their health was assessed mean that any significant effect on cancer risk, even after long-term use, can be ruled out.

The research, which covered more than half the Danes who started using a mobile between 1982 and 1995, found no increase in any of the forms of cancer that have been suggested as potential hazards of mobile phone use, including brain, neck and eye tumours and leukaemias.

“We found no evidence for an association between tumour risk and cellular telephone use among either short-term or long-term users,” said Christoffer Johansen, of the Danish Institute of Cancer Epidemiology, who led the research.

“Moreover, the narrow confidence intervals provide evidence that any large association of risk of cancer and cellular telephone use can be excluded.”

The results, which are published in the Journal of the National Cancer Institute, address the concerns of many mobile phone users about the negative impact their handsets may be having on their health.

There have been anecdotal reports of patients with brain and neck tumours who associate their diseases with making calls on a mobile, and a few preliminary studies have hinted at higher rates of cancer among heavy users. Larger investigations have failed to confirm a link, but while most scientists consider mobiles to be safe, few have been willing to rule out any risk because of a lack of long-term data.

As there are now 62.5 million handsets in use in Britain — more than one for every person — even a small risk would suggest that they could cause thousands of tumours. In 2000 the Stewart Report found no evidence of any danger, but recommended a precautionary approach to mobile use, particularly among children. The Danish study has now provided what many experts had been waiting for: definitive evidence from a large population, studied over many years, that mobiles are not linked to cancer. Dr Johansen’s team were given access to details of all 723,421 people who had a mobile phone in Denmark between 1982 and 1995.

Just over 200,000 corporate subscribers were removed as the individual user could not be identified; another 100,000 were eliminated because of duplicated addresses or errors.

The health of the remaining 420,095 users was then followed until 2002, by which time 14,249 cases of cancer had been recorded. The expected total was 15,001 cases, meaning that phones had no impact on cancer risk. The subjects had been using a mobile phone for an average of 8.5 years, and more than 55,000 people had had one for at least 10 years.

Dialling . . .

260,000 number of mobile phones in use in Britain in 1987

62.5m number of mobile phones in use in 2006

3 billion estimated number of texts sent monthly

47,000 base stations. One in three is a new structure

1.5kg typical weight of a 'brick' handset in 1985

90g average weight of a handset in 2006

Source: BMA, HPA, Vodafone

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