People living near power lines are exposed to significantly less radiation than electricity workers, so this research should lay to rest any concerns they may have

Brad Timms, Cancer Research Campaign

The researchers from the Institute of Occupational Health in Birmingham concluded there was "no discernible increased risk of death from brain cancer among workers in the electricity industry".

Almost 84,000 people employed in generating or transmitting electricity for the Central Electricity Generating Board of England and Wales between 1973 and 1997 were studied.

They had all worked for the company for at least six months.

Socio-economic factors

Researchers found brain cancer rates were not increased either by a lifetime's exposure, or exposure within the last five years.

The number of deaths from brain cancer throughout the study was 158.

In a comparative group in the general population, the expected figure would have been 146.4 - and the researchers said the difference was not statistically significant.

There were even indications from the last five years of data that exposure could protect against other cancers.

But the most important risk factor for increasing the risk of premature death was socio-economic factors.

The paper confirmed previous findings from the study of data from the company up to 1991.

In the paper, published in the Occupational and Environmental Medicine journal, lead researcher Professor Tom Sorahan wrote: "This large cohort study provides no evidence that United Kingdom electricity workers have an excess risk of brain tumours as a consequence of occupational exposure to magnetic fields."

'Important research'

Around 4,000 brain tumours are diagnosed every year. They can be benign or cancerous.

Brad Timms, science and information officer for the Cancer Research Campaign, told BBC News Online: "This research is important as it looked at a large number of subjects who would be at relatively high risk, due to prolonged exposure to electromagnetic fields.

"The finding, that there is no association between exposure to magnetic fields and brain tumours, is consistent with other major studies from around the world.

"People living near power lines are exposed to significantly less radiation than electricity workers, so this research should lay to rest any concerns they may have."

Dr Michael Clark, of the National Radiological Protection Board, said: "Workers tend to have higher exposures than members of the public, so you might expect to see a health effect in workers first.

"This study is important because it shows there is no increase in brain tumours in a large group of electricity workers exposed to electromagnetic fields.

"A similar study of the health of workers in the telecommunications industry is being carried out at present, and we look forward to the results being published in a few years time."