Hold that call: Cell phones aren't off the hook when it comes to cancer risk.

RODALE NEWS, EMMAUS, PA—It seems inevitable in scientific circles that as soon as one study comes out saying one thing, another study will come out just weeks later saying the exact opposite. So it shouldn't be all that surprising that after the International Agency for Research on Cancer (IARC) announced in early June that the radio frequency electromagnetic fields emitted by mobile phones would be classified as "possibly carcinogenic to humans," another study published this week would come to a conflicting conclusion—that it's unlikely an adult who uses a mobile phone would get cancer within 10 to 15 years.

THE DETAILS: The most recent analysis, published in the journal Environmental Health Perspectives, focused on the Interphone study, which was designed to study the link between mobile technology and cancer and includes participants from 13 countries. Interphone was controversial from the start, primarily because most of the funding came from the telecommunications industry, and its results were delayed for almost four years because the researchers behind it couldn't agree on their interpretation of the data. Ultimately, when the results of the study were released in May 2010, the authors found that the heaviest users (those who used phones for 30 minutes a day over a 10-year period) had a 15 percent increased risk of meningioma and a 40 percent increase in the risk of developing glioma; those are the two most common forms of brain tumors, although even they are relatively rare. But the study raised eyebrows when its results suggested that people who used mobile phones the least seemed to have lower incidences of brain tumors than people who used corded landlines.

In the current EHP analysis, scientists from the U.S., Sweden, and the United Kingdom took a harder look at Interphone and pointed out a few of the study's major flaws. For instance, data wasn't collected in a uniform manner from the 13 countries that participated in the study, and the links between tumors and phone use were all based on individual recollections of how often a phone was used, which isn't always reliable. Those scientists essentially concluded that Interphone didn't provide enough evidence one way or the other as to whether cellphones caused brain tumors. They also added that it's unlikely that adults will develop tumors within 10 to 15 years of first using a cellphone.

WHAT IT MEANS: Interestingly, the researchers at IARC also used the results of Interphone, along with a number of other animal studies on radio frequency electromagnetic fields, to come to their early-June conclusion that mobile phones might cause cancer. "These two groups represent the two camps regarding the Interphone studies," says Diana Zuckerman, PhD, president of the National Research Center for Women & Families and its Cancer Prevention and Treatment Fund. "IARC calls cellphones a possible carcinogen, which I believe is a very reasonable statement. The EHP authors say we don’t know for sure, but cellphones are probably safe." And that's an unreasonable assumption, she adds, because cancer can take 20 years or longer to develop, much longer than the 10- to 15-year period included in Interphone. "If we wait until there are better data 10 to 15 years from now, we could be very sorry. If there is an epidemic of brain cancer at that point, it will be too late for most of us to do anything to protect ourselves or our children."