Setting limits for mobile-tower radiation
Locals often oppose mobile-phone tower construction on the grounds of health concerns. The telcos, meanwhile, are quick to reassure that the amount of radiation emitted is not harmful — but how does the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) determine whether the towers are safe?
ARPANSA is an agency within the Department of Health and Ageing, and is responsible for setting the limits of the acceptable amount of radiation that human bodies can absorb within Australia. The agency's limits are then used to set rules for mobile-phone towers and other devices that emit electromagnetic radiation (EMR) on what the acceptable limit for emissions is.
Dr Lindsay Martin, manager with the non-ionising radiation branch of ARPANSA, told a parliamentary inquiry into mobile-phone towers today that in addition to analysing research and case studies from abroad, it is also necessary to test both humans and animals to determine the limits that have a physical impact, which usually registers as intense heat.
"[It] turns out the lowest [frequency] threshold ... changes animal behaviour when in their whole body the amount of absorbed energy exceeds a certain amount," he said. "The animals would stop pressing buttons to get food, or they'd go to another corner of the room.
"The number worked out fairly similarly for other animals, and it correlates fairly well with experiments you can do on human volunteers."
He said that at the top end of the spectrum of frequencies, the radiation is almost like rays of light, meaning that it hits the body, but doesn't go through. At the bottom end of the spectrum, the body acts like an antenna, and currents flow up and down in the body, he said. The mid-range spectrum is where it has a number of different effects.
"In the middle area, the body affects the radiation field. So you act like a bit of an antenna, and you still end up absorbing that energy, and heating the body and possibly producing some other effects."
In some instances, the only way to test the effects of radiation is to test the effect on nerves and muscles.
The lower end of the spectrum is favoured by telecommunications operators in Australia for their mobile networks, as this allows the signal to carry further and have better in-building penetration.
The impact of radiation from mobile towers is much lower for the average person than using a mobile phone or a Wi-Fi device, Martin said.
"The highest localised exposure to EMR for the general community occurs from a mobile-phone handset placed against the head," he said. Martin said that the difference is that using a phone exposes a small part of the body to intense EMR, while towers tend to expose the whole body to a much lower level of radiation.
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He said that the amount of radiation emitted on a mobile phone could be greater if the mobile network doesn't have good coverage.
"The modern mobile-phone handsets can reduce their power by more than a factor of 100 under good network conditions," he said, adding that 3G UMTS phones can operate at around 1 per cent of their full power.
"The GSM phones spend more time at full power when they're handing over from one base station to another. So if you're using a GSM phone in a train, the exposure may be higher."
In June last year, the World Health Organisation (WHO) released a study from its International Agency for Research of Cancer, which determined that mobile-phone use could be "possibly carcinogenic to humans". However, this rating is also applied to coffee, gasoline and pickled vegetables, and as widespread mobile use is still a relatively recent phenomenon, it will not be possible to know the long-term effects of radiation from mobile phones for a number of years.
The inquiry is examining legislation proposed by Independent MP Andrew Wilkie, who has — along with the Greens — called for wider community consultation for telcos wishing to construct low-impact towers. The inquiry has had 76 submissions, with close to 60 from residents and local community groups concerned about mobile-tower construction.
http://www.zdnet.com.au/setting-limits-for-mobile-tower-radiation-339331960.htm
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