CALIFORNIANS who use hands-free cellular devices while driving may be doing themselves a favor in the long run.
That's because scientists still can't say with certainty that placing a cellphone against the head is completely safe, especially for heavy users and people who began using the devices as children. They point to lingering questions over the potential health effects from the energy emitted by the phones, specifically the long-debated risk of developing brain cancer.
"It's fair to say that the data aren't all in yet," says Dr. David L. McCormick, a biologist and director of the Illinois Institute of Technology Research Institute in Chicago, who has studied the issue. "There are a small number of epidemiological studies that have suggested a possible increase in cancer risk. But comparable studies in other populations haven't confirmed these findings."
That's not to say anyone should panic. Cellphones do produce a type of radiation, but it's of the type called nonionizing radio frequency -- a form of energy located on the electromagnetic spectrum. At the high end of the spectrum, ionizing radiation, such as that emitted by X-ray machines, has well-known dangers. But the weak signals released by nonionizing radio frequencies do not cause DNA damage, and there is no explanation for how such energy could cause cancer, McCormick says.
Most studies have not consistently demonstrated a link between cellphone use and cancer, including two studies conducted by the National Cancer Institute. Several other studies coordinated through the International Agency for Research on Cancer, called the Interphone studies, have also failed to show an association. Numerous laboratory studies on animals have also found no evidence that DNA is damaged by low levels of radio frequency, McCormick says.
But the sheer number of people now using cellphones and the volume of use, as well as a few studies that found a potential link between brain cancer and cellphones, have kept the safety question looming.
'Unexpected results'
The National Academy of Sciences released a report in January calling for more research on cellphones and health risks. The authors concluded that many of the past studies were not conducted over a long-enough period of time to assess the risk of brain cancer, which typically develops slowly.
