By Jane Collingwood
From the beginning of mobile communications, concerns have been voiced over human exposure to electric and magnetic fields from the cell phone towers. Cancer and other health hazards have been suggested as possible risks, with children thought to be in particular danger. But is this anxiety justified?
A 2006 review found that “the strength of the available epidemiological and laboratory evidence falls short of what is normally required to establish a causal link.” But because of the remaining uncertainty, a cautious approach is often advocated.
Although cell phones and transmission masts are often linked together, they represent separate issues. Cell phone handset use is usually voluntary and controllable, whereas exposure from a mast, or base station, is involuntary. In terms of radio frequency energy, the delivery from a handset is typically around a thousand times more than that from a base station, but in terms of “outrage factor” the latter is more prominent.
Dr. Andrew W. Wood of Swinburne University of Technology, Victoria, Australia, says the greater concern among the public over proximity of cell phone transmission masts is understandable.
“The apparent unrestrained proliferation of masts and antennas, in some cases with minimal public consultation, has led to suspicion and organized protest, particularly where these facilities have been sited, or have been planned to be sited, near schools, child care centers, and the like. Although exposure levels, when measured, are very low (up to a few thousandths of the permitted levels), the continuous and whole‐body nature of the exposure gives the concern some justification.
“However, it must be remembered that cell phone transmissions are only part of the spectrum of electromagnetic field transmissions, along with radio, TV, and other communications networks. Radio transmitting towers have been operating for almost a century and in some cases at much higher levels of public exposure.”
Dr. Wood says there is ongoing debate regarding whether electromagnetic field exposure has sufficient evidence of harm to trigger a “precautionary principle.” Some countries have enacted policies on the location of masts, but the World Health Organization warns against “undermining the science base by incorporating arbitrary additional safety factors.” The scientific evidence of actual harm from phone towers is still not persuasive, Dr. Wood believes.
A very recent study found reassuring evidence that there is no link between cancer in young children and their mother’s exposure to cell phone masts during pregnancy.
Professor Paul Elliott of Imperial College, London, UK, and his team say this is the first study to look at phone masts in Britain as a whole. They looked at mother’s proximity to cell phone masts during pregnancy for 1,397 children who had cancer before the age of five years, compared with 5,588 similar children who did not. Types of childhood cancer included cancers of the brain and central nervous system, leukemia, and non-Hodgkin’s lymphomas.
Distance from a mast was no different between the groups, the researchers report on the website of the British Medical Journal. “Mean distance of registered address at birth from a macrocell base station, based on a national database of 76,890 base station antennas in 1996-2001, was similar for cases and controls,” they write.
Total power output of base stations within 700m of home address was also similar in the two groups. They conclude, “There is no association between risk of early childhood cancers and estimates of the mother’s exposure to cell phone base stations during pregnancy.”
Dr. John Bithell of the Childhood Cancer Research Group at the University of Oxford, UK, writes in an editorial that several studies have looked at the potential health effects of “ubiquitous” radiofrequency fields “with predominantly negative results.”
Despite levels of exposure from transmitters being much lower than those from cell phones, anxiety about an environmental risk persists. “Clinicians should reassure patients not to worry about proximity to cell phone masts,” Dr Bithell writes.
He adds that “the risks are dwarfed by the well-known dangers of distraction while using cell phones, especially when driving – even when using hands-free equipment. Clinicians should reassure patients not to worry about proximity to cell phone masts,” he urges.
The World Health Organization states that studies published over the past 15 years have not provided evidence that radiofrequency exposure from base stations increases the risk of cancer. “Likewise, long-term animal studies have not established an increased risk of cancer from exposure to radiofrequency fields, even at levels that are much higher than produced by base stations and wireless networks.”
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