London: People who are exposed to very low frequency electromagnetic fields at workplace - such as pilots and welders - may be at double the risk of developing ALS, the most common form of motor neurone disease, scientists warned today.
Amyotrophic lateral sclerosis (ALS) is a neurological disease, characterised by progressive degeneration of the motor nerve cells in the brain and spinal cord.
There is currently no cure, and those affected usually die within a few years of diagnosis. Researchers relied on data from the Netherlands Cohort Study that involves more than 58,000 men and more than 62,000 women, who were all aged between 55 and 69 when they were first entered the study in 1986.
Participants who had died of motor neurone disease (76 men and 60 women) were compared with around 4,000 (2411 men and 2589 women) who had been randomly selected for the purposes of the current study. Their detailed employment histories were converted into workplace exposure to solvents, pesticides, metals, extremely low frequency magnetic fields and electric shocks.
"ELF-MF are magnetic fields produced by electrical appliances and the power grid, with a frequency up to 300 Hz," said Roel Vermeulen, from Utrecht University in Netherlands. "Jobs with relatively higher ELF-MF levels are for
example: electric line installer, repairers and cable jointer, welders, sewing-machine operators, air craft pilots - essentially jobs where workers are placed in close proximity to appliances that use a lot of electricity," said Vermeulen.
High levels of electromagnetic field exposure were largely confined to the men, and depended on job type. These ranged from two to 25 per cent among the men; among the women, the equivalent figure was upto per cent. Participants' neurological health was then tracked for an average of 17 years to see if any of them succumbed to ALS. During this time, 76 men and 60 women died of ALS.
Occupational exposure to extremely low frequency electromagnetic fields was associated with a heightened risk of developing ALS among the men. Those whose jobs had exposed them to high levels of extremely low electromagnetic fields were more than twice as likely to develop ALS as those who had never been exposed through their work. Furthermore, those in the top 30 per cent of cumulative exposure were nearly twice as likely to develop the disease.
The other occupational factors assessed were only weakly associated with ALS risk in both men and women, and there was no clear evidence of a linear increase in risk according to the amount of cumulative exposure, researchers said. The findings strengthen the evidence suggesting that ALS may be linked to workplace exposure to extremely low electromagnetic fields, they said.
