The ongoing debate over cellphone safety ratcheted up significantly last month. On July 24, University of Pittsburgh Cancer Institute director, Dr. Ronald Herberman, an internationally respected scientist and cancer researcher, issued a warning to the institution’s 3,000 faculty and staff members to limit cellphone use “because of the possible risk of cancer.” 

Herberman’s widely reported memo did not result from any specific new information surrounding the long-simmering controversy over whether the small amounts of radio frequency energy emitted by cellphones may be linked to brain, head and neck tumours.

Rather, he and his colleague, Dr. Devra Lee Davis, the university’s director of environmental oncology, were concerned that, because science moves slowly, real answers about harmful effects, especially to children whose developing brains may be more susceptible than adults, are likely years away.

“Really, at the heart of my concern is that we shouldn’t wait for a definitive study to come out, but err on the side of being safe rather than sorry later,” Herberman told reporters at a press conference.

While many experts publicly disagreed, citing a number of large population studies that failed to detect a cancer link, Herberman and Davis are not alone in their worry. Similar concerns about “potential health risks” have resulted in governments in Ontario, the U.K., France and India advising that children should be discouraged from using cellphones except in an emergency.

That approach appears prudent. While most of the earlier reports failed to demonstrate an increased risk of brain tumours in cellphone users, a meta-analysis of previously published studies, appearing in the May 2008 issue of the International Journal of Oncology, may provide an important clue.

The Swedish authors of the meta-analysis found no overall increased risk of brain cancer (glioma) in the combined results of 10 studies. However, they discovered that long-term (10 or more years) cellphone users who reported always holding the device to the same ear had double the incidence of same-side (ipsilateral) gliomas. An increase was also observed in the incidence of ipsilateral benign nerve tumours, called acoustic neuromas, in long-term, same-ear cellphone users.

Similarly, a recently published Israeli study demonstrated a 50 per cent increase in ipsilateral salivary gland tumours in long-term, same-ear cellphone users.

The weakness in all these studies is that they are retrospective and depend heavily on peoples’ memories over a period of many years. New studies must try to overcome this deficiency, if possible by a prospective (forward) design that employs a diary for each subject to document frequency and length of time of cellphone use, and whether the cellphone is held to one ear more often than the other.

Even officials at the United States Food and Drug Administration (FDA) are somewhat cautious in drawing firm conclusions about cellphone safety.

"We don't see a risk looking at currently available data, but we need more definite answers about the biological effects of cellphone radiation, and about the more complicated question of whether mobile phones might cause even a small increase in the risk of developing cancer," Dr. David Feigal, director of the FDA's Center for Devices and Radiological Health, commented in the agency’s publication, FDA Consumer Magazine.

To that end, the FDA is collaborating in an advisory role with the Cellular Telecommunications Industry Association (CTIA) on the design, conduct and analysis of new studies. The FDA’s sister agency, the U.S. National Cancer Institute, is conducting its own research on long-term cellphone use and brain cancer.

My own view is that Herberman is right when he says that “science is slow” and, until methodical assessment gives us a firm “yes” or “no,” cellphones should be used temperately. They should be placed over each ear equally, connected to an ear piece when possible and children should be discouraged from using them except when necessary.

Most importantly, they should not be used while driving. As opposed to the disagreement about potential cancer risk, all studies conclude that talking on a cellphone in traffic increases the chance of injury or death in a car accident.