WASHINGTON, D.C.--The question over whether cell phones pose a health risk has been debated for years, and researchers say the final answer could still be years away.
Since the wireless industry's early days, there have been fears that cell phones could be harmful to your health. Some 600 studies have been conducted on the health effects of cell phone use, but the results have been conflicting.
Several reputable organizations, including the World Health Organization and the National Cancer Institute, say there's no conclusive evidence that using cell phones can harm your health. Other independent research, meanwhile, indicates a link between health problems and cell phone use. (See also: CNET's Quick Guide: Cell phone radiation levels)
The Interphone study, which began over a decade ago involving 13 countries and has been funded in part by the wireless industry, was supposed to settle the dispute. But the report's publication has been delayed as researchers disagree over how to interpret the data. Some countries have ended up publishing some results on their own. Much of it indicates there is a link between brain tumors and cell phone use of 10 years or more.
As this research becomes public, some well-respected scientists in the fields of cancer research, epidemiology, electrical and computer engineering, and electromagnetic radiation say they see reason for concern, while others say it is much too soon to make judgments.
But one thing they all agree on is that more research is needed.
For three days this week, many of those scientists are gathering at an international conference here to share research and plot the course for further studies to look at the effects of cell phone use and health concerns. Some are also testifying at a Senate hearing on Monday to look more deeply at the public health risks.
At this point, researchers have strong data indicating how much radiation that humans absorb through cell phone use. Thanks to the work of scientists, such as by Niels Kuster, a radiation expert at the Swiss Federal Institute of Technology, and Om Gandhi, a professor and researcher at the University of Utah, there are now reliable models to assess radiation absorption from using cell phones.
A key finding of Kuster's research, which was presented Sunday on the first day of the conference, indicates that children absorb twice as much radiation from cell phones as adults do, mostly because their faces and heads are much smaller. And even though no one knows for certain what the health implications of this absorption is, many countries including Finland and France, have issued warnings to parents urging them not to allow their children to use cell phones.
Now, researchers say they must look at how radiation that is absorbed into the body affects electrons, chemical reactions, and ultimately how it could change human biology.
"From here you build a chain that then points to health effects," said Frank Barnes, distinguished professor of electrical and computer engineering at the University of Colorado at Boulder.
Looking at "most plausible mechanisms"
Scientists know ionizing radiation causes a break in DNA that can lead to cancer. But cell phones operate well below such frequencies. As a result, some scientists have argued that non-ionizing radiation is too low-power to cause cell damage. Others say the effects of non-ionizing radiation on cells and DNA is still not known.
"The question becomes how can you accept the epidemiologic research, if it's not plausible from a biological standpoint?" said Ronald Herberman, director emeritus of the University of Pittsburgh Cancer Institute. "Through research, we need to focus on the most plausible mechanisms and see if there is a connection. There might not be direct damage to DNA, but there could be damage to how cells repair themselves, or there could be some other mechanism."
Herberman, a prominent cancer researcher, ignited a firestorm of criticism last year when he issued a controversial warning to his staff urging them to limit cell phone use. He said results from recent studies, growing concern among European governments, and unpublished results from the Interphone study, were enough to prompt him to write the memo.
"Many of my colleagues in cancer research thought I had gone off the reservation," he admitted. But he said he felt that it was better to err on the side of caution in this situation.
Still, Herberman has been critical of some of the research that has been done.
"Most of the studies were not well-designed," he said.
Herberman said researchers need to apply the same type of process to studying the potential biological markers in their studies of cell phone radiation that cancer researchers have used in studying other causes of cancer. He also recommends researchers obtain more reliable data on actual cell phone usage. A key problem in studying the epidemiology of cancer associated with cell phone use is the fact that most of the research concerning humans relies on patients providing information about usage patterns.
"In some of these studies, they have asked people to remember how often they used the phone or in some cases they are asking family members of deceased subjects," he said. "So you are going to get some inaccurate estimates. What is really needed is for the wireless industry to provide detailed usage information."
Herberman said he asked wireless operators to provide this information during his testimony last year at a congressional hearing called by Rep. Dennis Kucinich, D-Ohio. But so far the industry has been silent, Herberman said.
Too early for alarm?
While researchers, such as Herberman, say there is enough information to be "concerned," others say it is still too early to sound the alarms.
Michael Thun, vice president emeritus of Epidemiology and Surveillance Research for the American Cancer Society, who is attending this week's conference, said there is nothing to suggest that cell phone use has spurred a significant increase in brain cancer incidences. He said it could be too early to know for sure if there are long-term effects of using a cell phone, because cancer often takes decades to manifest.
For example, he said that it took 30 to 40 years after cigarette mass-production began before epidemiologists saw a big surge in lung cancer. By the 1950s, lung cancer rates had increased nine-fold.
Thun said that the scariest studies about cell phone use, such as the ones from Sweden indicating brain tumors growing on the same side of the head where subjects mostly used their phones, are the hardest to interpret because the timing appears to be inconsistent. These studies suggest that these tumors are appearing within 10 years. And Thun said these types of tumors often grow much slower than that.
"It just doesn't fit what you would expect," he said. "But the wireless industry is advancing very quickly, and it's certainly important to track. There are 3 to 4 billion people using this technology throughout the world, so it's an important question to answer."