Studies Find No Short-Term Links of Cell Phones to Tumors

Cell-phone use does not appear to cause brain tumors, at least over a period of two to three years, according to two large new studies released today.

The studies, which involved 1,250 brain tumor patients and an equal number of healthy individuals, found no increased risk of cancers among those who used the electronic devices more frequently.

The studies are not likely to put the issue of potential harm completely to rest, but they join a growing body of evidence suggesting that the only important risk associated with the hand-held devices is a higher likelihood of traffic accidents.

“In all of the available scientific literature, there is nothing that indicates any adverse health effects from using cell phones,” said Russell Owen, chief of the Food and Drug Administration’s radiation biology branch.

One of the new studies is published in today’s Journal of the American Medical Assn. (JAMA). The second is scheduled to be published next month in the New England Journal of Medicine, but was posted on the journal’s Web site (https://www.nejm.com) Tuesday.

The two studies leave open the question of whether longer use of the devices could pose a problem. That issue is being addressed in a still larger European study now underway, but results are not expected until 2003 at the earliest.

“The question that is important to bear in mind at this point is, have there been any studies that clearly point to an increased risk of brain cancer from cell-phone use?” said Dr. Peter Inskip of the National Cancer Institute, lead author of the New England Journal study. “I believe that the answer is no. Does that mean we can prove they are safe? No.”

Critics have been concerned about the possibility of hazards from cell phones since the early 1990s because the devices transmit radio frequency energy from an antenna held next to the head. Although the radiation is not at a frequency that would damage DNA, some phones emit microwave radiation that could heat tissue.

Studies have shown, however, that the low power of the phones produces an increase of only about a tenth of a degree in the temperature of adjacent cells, much less than the normal fluctuation in cellular temperature.

The new studies further support the idea that fears may have been exaggerated.

In the JAMA study, a team headed by epidemiologist Joshua Muscat of the American Health Foundation in Valhalla, N.Y., and Dr. Mark Malkin of Memorial Sloan-Kettering Cancer Center in New York City studied 469 men and women, ages 18 to 80.

The subjects were diagnosed with brain cancer between 1994 and 1998. They were compared with 422 people who were closely matched by age, sex, race, years of education and occupation, but who did not have brain cancer.

Researchers found that both groups used cell phones about three hours or less each month and that both had used them for an average of slightly less than three years. They also found no link between which hand routinely held the phone and the side of the head on which a cancer occurred.

“We’re now in a much better situation than we were in 1994” when concerns about cell phones arose, Malkin said. “Then, we had absolutely no human data on whether there was or was not a risk. Now we do,” and the data, he said, indicate the risk is very low.

The second study, in the New England Journal, was similar. Inskip and his colleagues studied 782 patients who were diagnosed with brain tumors between 1994 and 1998 and compared them with 799 people who were admitted to the same hospitals for conditions other than cancer.

They also found no increased risk of tumors among people who used cell phones more frequently, and they also found that tumors did not occur more often on the side of the head on which the telephone was typically used.

But Inskip cautioned that many carcinogens produce tumors only after a long period of time, so it is important to have long-term studies. For this reason, researchers are eagerly awaiting the European study, which is being conducted by the International Agency for Research on Cancer.

That study is being conducted in countries where widespread cell-phone use began earlier than it did in the United States, so it should provide more information about long-term exposure.

Meanwhile, Owen cautioned against using devices that attach to the earpiece or antenna and purport to block radiation from the phones from reaching the head. Some of those, he said, could prevent phones from operating and others could actually make them produce higher emissions.

“We don’t recommend them,” he said. “When you can’t demonstrate an adverse health effect, it’s impossible to substantiate claims of a health benefit from such a product.”

The JAMA study was funded by the U.S. Public Health Service and the cellular phone industry, and the NEJM study by the National Cancer Institute.