Time to dismiss cell phone-cancer link?

WASHINGTON, April 11 (UPI) -- Two recent studies, including one released Monday, looked at the putative link between cell phones and brain tumors and reached the same conclusion as the bulk of previous studies on the issue: the data so far show cell phones do not cause cancer.

The accumulation of studies, nearly all dismissing the cell phone-cancer connection, has led major public health organizations, such as the Food and Drug Administration, the American Cancer Society and the World Health Organization, to conclude there is no evidence to date to suggest an increased risk of cancer from using cell phones.

So can the book finally be closed on the issue? Almost, but not quite, said Dr. Christoffer Johansen of the Danish Cancer Society in Copenhagen, who led the study released Monday that appears in the April 12 issue of the journal Neurology.

"We cannot rule it out entirely, but we are close," Johansen told United Press International.

Still left to be done, he said, are studies of heavy users and long-term users. One such study already in progress, by the Swedish Interphone Study Group, could help answer the heavy-user question, said Johansen, who also is head of the DCS's Department of Psychosocial Cancer Research.

The long-term use question might have to wait until there has been an adequate number of adults who were exposed during their childhood and adolescence, he said.

Stephen Lonn of the Karolinska Institute in Stockholm told UPI the results of the Interphone study, which consists of 14 ongoing studies, will be released later this year or early in 2006.

Lonn published a study last month in the American Journal of Epidemiology that found no increased risk of gliomas or meningiomas -- two common types of brain tumors -- among those who reported using a cell phone for 10 years or longer. He agreed, though, that long-term users need to be more thoroughly studied.

"The overall evidence is that mobile phones are not linked with brain tumors, but it is important to note that long-term use cannot be studied yet with any good precision," Lonn said. "We need more research for long-term use and research among children before we could make any conclusions."

Another study, which Lonn and others conducted last year as part of the Interphone study, found an increased risk of a type of tumor of the inner ear, called an acoustic neuroma, in people who had used cell phones for 10 years or longer. No increased risk was seen in those who had less than 10 years of cell phone use.

In Johansen's study, his team asked 427 people with brain tumors and 822 people without brain tumors about their cell-phone habits. There was no increased risk for brain tumors associated with cell-phone use, frequency of use or number of years of use. In addition, brain tumors did not occur more frequently on the side of the head where the cell phone typically was used.

This finding is in line with previous studies, but few long-term or frequent cell-phone users were involved in any of the research. A small percentage of the participants in Johansen's study reported regular cell-phone use for 10 years or longer, he said, but drawing firm conclusions will require additional studies with more long-term and frequent users.

"The mechanisms are suggestive but not convincing," Johansen said.

The initial concern was cell phones emitted radiation that could cause cancer, but the energy of this radiation generally is not enough to damage DNA or break chemical bonds, and thus probably does not cause tumors to form, Johansen's team wrote in Neurology.

Another proposed mechanism involves cell phones inducing cancer via the heat generated by the emitted radiation, but the amount of heat is too small, according to the National Cancer Institute.

"There's really no biological reason to believe there's a risk," said Dr. Michael Thun, head of epidemiological research for the American Cancer Society in Atlanta.

Thun agreed, however, it still is too early to conclude that cell phones do not cause cancer. He said Lonn's study involving acoustic neuromas was small, so it would be difficult to know if the finding was significant.

"It's something to look at in a larger study, but at this point you don't know whether it's chance or not," he said.

In addition, the study results apply only to analog phones, which require a stronger radio signal. Most phones in use today in the United States are digital.

"The evidence we have now strongly suggests there's not a problem, but it's virtually impossible to prove something is entirely safe," Thun told UPI.

He said he is more concerned about the "already proven relationship" of having an automobile accident while using a cell phone and is surprised that hazard does not merit more attention.

In 2000, the FDA collaborated with the CTIA-Wireless Association, a group representing the cell phone industry, to conduct studies of cell phone safety over three to five years, and those findings will be published soon, Julie Zawisza, an agency spokeswoman, told UPI. The FDA's current position, as noted on its Web site, is, "The scientific evidence does not show a danger to users of wireless communication devices, including children."

Joe Ferrin, a CTIA-Wireless Association spokesman, told UPI, "The issue needs to be guided by science and the overwhelming majority of studies that have been published in scientific journals around the world show that wireless phones do not pose a health risk."

In the meantime, there are precautions people can take to lower their exposure if they are concerned about the risks.

"Using hands-free devices usually decreases the exposure to the head around 90 percent," Lonn said.

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