<b style="color:#900;">special report</b> Despite years of research, there's little consensus on whether you should be worried about your well-being. CNET explains why experts looking at the same data have completely different conclusions.
Marguerite ReardonFormer senior reporter
Marguerite Reardon started as a CNET News reporter in 2004, covering cellphone services, broadband, citywide Wi-Fi, the Net neutrality debate and the consolidation of the phone companies.
Editors' note: This is the first of a three-part series on issues related to cell phone radiation. Look for Thursday's story on safety standards and testing and Monday's story on what consumers can do to reduce their radiation exposure.
Updated 11:00 a.m. PT:This story was updated with information from the IARC, an arm of the World Health Organization, that recently determined cell phones may cause cancer. A statement from the CTIA, wireless trade association was also added.
A typical day for Jonathan Hirshon, a San Francisco-based public relations representative, is spent with his iPhone 4 pressed to his head for two or three hours.
What does he fret about while he's using that phone? He hopes he can make it through an entire conversation without his call being dropped; he hopes his voice is clear enough that the people on the other end of the call can understand him; and he hopes AT&T doesn't take away his unlimited data plan.
You may not be very surprised to hear that the one thing Hirshon, whose first cell phone was the groundbreaking 1996 Motorola StarTAC, doesn't spend much time worrying about is whether his heavy cell phone use will give him brain cancer.
"Is it a worry? Maybe," he said. "But for me I need to use my phone. And until I see some evidence that has been verified by five different, reputable sources that say I'll get cancer tomorrow, I can't change my behavior."
Hirshon may have more luck waiting for the Rapture than consensus on the risks of cell phone radiation. For years, consumer advocates and scientists have questioned the safety of cell phones. Scientists know that humans absorb radiation from cell phones, but whether that radiation causes health risks, such as cancer, is unclear.
Why is it still unclear? There's plenty of blame to go around. The research is often contradictory, sometimes based on outdated data, sometimes driven by industry groups soft-pedaling concerns, sometimes driven by health advocates who appear too alarmist and unreasonable. About the only thing researchers agree on is that they need to do more research.
What's more, a close look at the research used to set federal safety standards indicates that the standards themselves may be outdated at best and could be meaningless at worst. Some countries, like Finland and France, are concerned enough to issue public warnings, especially when it comes to allowing children to use cell phones. And some local and state governments in the U.S., such as San Francisco and the state of Maine, have tried to create their own warning labels for cell phone use despite the lack of consensus.
There's no question that cell phones are here to stay, but how concerned should consumers be about a potential health risk from using these devices that have become such an important part of our lives? Are the safety standards that we have today sufficient to protect us? And what can consumers do now to protect themselves from potentially damaging exposure?
In this three-part special report, CNET takes a look at the maddening state of cell phone safety research. We will explain how regulators came up with the safety standards and how they test devices. Finally, we will look at what consumers can do to protect themselves and discuss what some communities are doing to make sense of this mess. We will also publish a Q&A with Devra Davis--an epidemiologist, author, and founder of the Environmental Health Trust--about her new book "Disconnect: The Truth about Cell Phone Radiation, What the Industry Has Done to Hide it and How to Protect Your Family."
The science In 2000, a Maryland neurologist named Christopher Newman filed an $800 million lawsuit against Motorola and Verizon. His claim was that using his cellular phone caused the brain cancer that he had been diagnosed with in 1998.
Newman used a cell phone for an estimated 343 hours from October 1992 until his March 1998 diagnosis of a brain tumor. That adds up to about 1.2 hours of talk-time per week. Newman said he held his cell phone with his right hand next to his right ear, the area where the tumor developed.
But like a lawsuit filed in 1993 by Florida resident David Reynard, who claimed that radiation from cell phones caused or accelerated the growth of a brain tumor in his wife, Newman lost his lawsuit.
But there are potential issues related to that conclusion that stem from how cell phones work and how radiation can hurt you. Experts say the concern over cell phone use stems from a form of radiation that's produced when these wireless devices communicate with cell towers using radio frequency. High-frequency radiation, such as the kind that's used in X-rays, is known to cause cancer in high doses.
Cell phones emit much lower frequency radiation, but it's unknown whether these milder forms of radio frequency (RF) can cause adverse biological changes to humans. But the fact that cell phones are often held close to the body, either right alongside the head or in a pocket, has caused some concern among researchers who believe that radio frequency energy is being absorbed into the body and can cause damage to cells or even alter cell phone users' DNA. Even holding a phone 10 millimeters away from your head could decrease the exposure of RF radiation to the body by about 100 times.
Researchers used scans of the brain to measure brain activity in 47 healthy participants when they had cell phones held to their ears in both off and on positions. (When they were on the phones were muted.) The study examined the brain's consumption of glucose to measure brain activity.
A cell phone turned on for more than 50 minutes increased brain activity by about 7 percent in the regions of the brain that were closest to the antenna. This, they concluded, suggests that cell phone use stimulates or excites brain activity.
Health effects? But is that bad? Here's that maddening problem with cell phone radiation research, again: Right now, we don't know. The study's authors were careful to point out that their findings were of "unknown clinical significance" and that more research is needed.
In other words, even though there is no proven link between cell phone radiation and adverse health effects, the human brain is sensitive to and reacts to low levels of electromagnetic frequencies transmitted from a cell phone. But whether that is a bad thing or merely a statistical point of note is unclear.
Devra Davis, an epidemiologist who recently published the book "Disconnect: The Truth about Cell Phone Radiation, What the Industry Has Done to Hide it and How to Protect Your Family," called the study's results stunning: "This demonstrates that cell phone use affects brain activity," she told CNET. "The study used real people and was as close as you can get to a biopsy on a living brain."
But she too said more research is needed. "The notion that we have enough information is completely wrong," she said.
Several animal studies that have been done over the years do show cellular changes due to low levels of cell phone exposure. Some of these studies date back several years and were cited in the Newman lawsuit a decade ago.
"The overall conclusion of no increased risk is in accordance with the large body of existing research and many expert reviews that consistently conclude that there is no established health risk from radio signals that comply with international safety recommendations."
--Jack Rowley, GSM Association
But to be clear, there are no studies that conclusively link cell phone use to adverse health effects. Studying populations for the effects of cell phone use is difficult for several reasons. For one, brain tumors can be very slow-growing, taking decades to manifest. And second, epidemiological studies that study a particular population rely on surveys answered by patients and they are often fraught with bias.
An ambitious, decade-long study by the World Health Organization did little to clear up confusion. After spending 10 years and $24 million to see whether cell phone use leads to brain cancer, the WHO's verdict was inconclusive. The Interphone study, which gathered 21 scientists from around the world to study 13,000 individuals in 13 different countries, was the largest research program to study the effects of cell phone radiation to date.
Collection of data for the study was completed in 2004. Part of the results were analyzed and published in 2010. But scientists are still evaluating the data and more studies will likely be published in the coming years using the data. Some countries have published individual findings from the data, as well.
Initially, the WHO's International Agency for Research on Cancer (IARC) said that most cell phone use did not lead to an increased risk of either meningioma, a common but typically benign form of cancer, or glioma, a rare but more dangerous type of brain cancer. But the group conceded that more research is needed, especially since cell phone use has increased dramatically since 2000, particularly among younger people.
But today, WHO issued a report based on the findings of a team of of 31 scientists from 14 countries, including the United States, who considered peer-reviewed studies about the safety of cell phones. The team said that it had found enough evidence from the studies it examined to consider exposure to cell phone radiation as "possibly carcinogenic to humans."
By putting cell phone radiation in this category, the IARC is basically saying that there is some evidence in humans, which suggests there is a credible chance that cell phones may cause cancer. But other risk factors or causes have also not been ruled out. In other words, more study is needed. Other things that fall into this category of "possibly carcinogenic to humans," include gasoline engine fumes, lead, and coffee.
The wireless industry group CTIA was quick to point out that the IARC did not determine that cell phones actually cause cancer.
"IARC conducts numerous reviews and in the past has given the same score to, for example, pickled vegetables and coffee," said John Walls, vice president, public affairs for CTIA-The Wireless Association. "This IARC classification does not mean cell phones cause cancer. Under IARC rules, limited evidence from statistical studies can be found even though bias and other data flaws may be the basis for the results."
Still, results from the Interphone study have been interpreted by some experts to suggest that people who use a cell phone for at least an hour each day over a 10-year period are at an increased risk of developing some brain tumors. This research, these experts argue, also suggests that these tumors are more likely to be on the side of the head where the phone is most often used.
However, the authors of the epidemiological studies that came to these conclusions have acknowledged that possible biases and errors from those participating in the survey meant that these results were not conclusive enough to directly blame cell phone radiation for such tumors. For example, critics of these studies say that subjects may have recall bias. Subjects in the study diagnosed with brain tumors may have better recall of how often they used their cell phones and on which side of their heads they usually placed their phones than the control groups that do not suffer from these ailments.
Still, the cell phone industry, which provided about 25 percent of the total $24 million needed to fund the Interphone study, has taken the inconclusive results as further evidence that cell phones are safe.
"The overall conclusion of no increased risk is in accordance with the large body of existing research and many expert reviews that consistently conclude that there is no established health risk from radio signals that comply with international safety recommendations," Dr. Jack Rowley, director of research at the GSM Association, said in a statement. "The results reported today underscore the importance of utilizing complete and thorough data analysis before reaching conclusions." The GSM Association is an international trade association for wireless operators and cell phone makers that offer products and services using the GSM mobile technology standards.
Davis, who has become a crusader in the fight over cell phone safety and is also the founder of Environmental Health Trust, has advocated for years that studies include research on the effects of cell phone radiation on children.
"The notion that we have enough information is completely wrong."
--Devra Davis, epidemiologist and author
One reason for concern is the fact that children who start using cell phones at a young age will inevitably have more exposure over their entire lifetime to cell phone radiation. But researchers are also concerned about the risk of cell phones with children, because children's nervous systems are not fully developed. Also, their brains contain more fluid than brains of adults, which allows for deeper penetration of radiation. And finally, children's skulls are not as thick as those of adults.
"The reality is that the head of a child is different in terms of density of the bone and the amount of fluid in the brain than that of an adult," Davis said. "And we know that the more fluid there is an object, the more deeply the radio signal can penetrate."
Davis and other advocates would like to see more studies done on the effects of radiation on children. And they'd like to see the models that the FCC uses to test cell phones reflect the physical realities of a child's head and body. The model used today to test cell phones is based on the size of an adult man weighing 200 pounds.
At this point, we still don't have all the answers as to whether cell phones present a risk to our health. For people like Hirshon, they aren't losing sleep over it.
"Look, I live in California and I know the Big One (earthquake) is probably coming eventually," he said. "I have a preparedness kit. But worrying about it everyday won't change anything. I feel the same way about potential cell phone risks. It doesn't make sense to worry about it."
CNET Reviews Senior Editor Kent German contributed to this report.
Coming Thursday: A look at how the FCC came up with its cell phone radiation standards and why some researchers say those standards are bunk.