Expectant parents may have one less thing to worry about. British researchers say a new study shows that the children of women who live near cellphone towers during pregnancy do not have an increased risk of childhood cancer.
The researchers, from Imperial College London's School of Public Health, identified all 1,926 cases of childhood cancers in Britain from 1999 to 2001. In 529 cases, either the mother's whereabouts during pregnancy or the radio-frequency exposure from nearby cellphone towers could not be determined. Each of the remaining 1,397 cases was matched with four healthy children of the same age and gender. All of the kids had similar demographic characteristics.
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The team also gathered detailed data about all 81,781 cellphone towers that were operational in the country during that time, including each tower's location, height, output power and how many antennas it had.
Then they crunched the numbers. In virtually every permutation of their calculations, there was no correlation between the cellphone towers and the cancer cases.
For instance, the mothers whose children were diagnosed with cancer lived an average of 1,173 yards from a cellphone tower while they were pregnant—statistically indistinguishable from the 1,211 yards that separated the other pregnant women from their nearest cellphone towers. Tallying up the total power output of all cellphone towers within 766 yards of each pregnant woman's home, they found that both groups had nearly the same exposure — 2.89 kilowatts for the mothers of cancer victims and 3.00 kilowatts for the other mothers.
Only one of their models revealed a difference that was statistically significant, though just barely. In that case, higher radio-frequency exposure was associated with a reduced risk of cancer of the brain or central nervous system. (This result calls to mind a mouse study from last year that found that electromagnetic radiation from cellphones actually protected mice from Alzheimer's.) The results were published online Tuesday by the British Medical Journal.
The British researchers admitted their study would have been stronger if there had been some way to determine the actual radiation exposure for each pregnant woman instead of relying on mathematical models. They also would have liked to have tracked the exposure of babies after they were born, but the necessary data weren't available. Still, they said that if the cellphone towers had doubled the risk for these childhood cancers, the odds that their study would have picked up on it were greater than 90 percent.
In an editorial, John Bithell of the University of Oxford's Childhood Cancer Research Group wrote that the study was convincing.
“Clinicians should reassure patients not to worry about proximity to mobile phone masts,” they wrote. “Moving away from a mast, with all its stresses and costs, cannot be justified on health grounds in light of current evidence.”