Throughout my seven years of reviewing cell phones and covering the wireless industry for CNET, the issue of a possible link between cell phones and brain cancer has surfaced every few months. And as my colleague Marguerite Reardon explains in her comprehensive feature, the debate isn't going away anytime soon. Indeed, research abounds on the subject, and there are plenty of voices on both sides. Some say there's nothing to worry about, and others recommend proceeding with care.
One voice on the cautionary side is Dr. Devra Davis, the author of the 2010 book "Disconnect: The Truth about Cell Phone Radiation, What the Industry Has Done to Hide it and How to Protect Your Family." An epidemiologist and environmental health researcher, Davis is a founding director of the toxicology and environmental studies board of the National Academy of Sciences and founder of the Environmental Health Trust. Davis argues that cell phone use can have very real effects on health, and that cancer is only part of the story.
A few months ago, I interviewed Dr. Davis after reading her book. Though I can tell you a lot about cell phones, I'm not a scientist, and frankly, I wasn't very good at science in school. Yet, I approached the subject with a genuine curiosity, and I was glad to see that Davis breaks down her arguments in a manner that's easy to follow. The material is accessible and digestible, even if it's a bit scattered in places. And though the book's title is over the top, Davis takes a more measured tone inside. She's no alarmist, but she forcefully advocates that more research is needed. And while she does use a cell phone regularly, she also suggests that cell phone users take small steps to reduce radio frequency (RF) energy.
Q: What is the one thing that you want readers to take away from your book?
Davis: If we fail to pay attention to experimental evidence, we're treating people as subjects in an experiment with no controls. And if we say that we'll accept that cell phone radiation is harmful only when we have enough sick or dead people, then we're dooming three generations to illness.
The chapter that I think is most important is the one that discusses the effects on male reproductive health. A phone in a pocket may be linked to lower sperm count. This is not a confirmed association, but I've talked to several urologists who have begun to advise men that they should not keep the phone in their pocket if they're concerned about libido or impotence. That's not to say that they're the cause of impotence; like everything else in health, it's multifactorial and there can be multiple explanations.
How did you first become interested in this issue?
Davis: About six years ago my grandson was born. I saw the incredible enthusiasm he had toward a cell phone, and I began to wonder about its safety. Later, I worked for Dr. Ronald Herbermann at the Center for Environmental Oncology at the University of Pittsburgh. I was stunned by what I found.
In your opinion, what is the most significant study on cell phone radiation?
Davis: I think that there is no single study that is "the most significant," and this is due to the fact that each study uses a particular approach, methodology, or "angle" to ask a biological question. However, there are several studies, that when taken together, all found that the nonionizing radiation that cell phones produce causes biological perturbations in live organisms.
[Editor's note: Shortly after this interview, researchers at the National Institutes of Health found that in healthy volunteer participants, cell phone exposure was associated with increased metabolism of glucose in the region of the brain closest to the antenna. At the time, Davis told CNET that the "stunning" study demonstrated that "cell phone use affects brain activity" and that it "was as close as you can get to a biopsy on a living brain."]
You wrote that the incidence of brain tumors is increasing in Americans aged 20 to 40. Couldn't there be other contributing stimuli beyond cell phones?
Davis: There's almost no environmental cause that we know, that causes an increase [of brain cancer] in the population within 10 years--not tobacco, not asbestos, not vinyl chloride. The fact that some studies have found a double or more increase in brain tumors of highly exposed users of cell phones I think is very worrisome.
But you understand that some people will debate that finding, correct?
Davis: I understand that science can make mistakes. But I don't want to see people die. If you hold it to the standard of human proof alone, we don't have the full story yet. But if you do what I think we should do as a modern civilization, then we should rely on the full panoply of science. Sperm exposed to cell phone radiation die three times faster. This can't be a good thing.
When do we decide that a correlation indicates causation?
Davis: That decision is not merely a scientific decision of rules of inference and deduction, but ultimately a policy decision. Think about the history of tobacco, asbestos, and hormone replacement therapy. Can anyone seriously suggest that we acted appropriately when discussing the danger in those cases? In fact, only after overwhelming evidence of human tragedy mounted was action finally taken. And we are paying the price today for failing to take precautionary policies in the form of avoidable deaths around the world.
You recommend that consumers limit their exposure by using headsets, for example, and that they not carry their phone for long periods close to the body. Those steps won't always be practical for some users, so what else would you like to see happen?
Davis: I'm confident that we can design our way out of this problem. We can better design phones to reduce radiation exposure, and there are ways for consumers to check their phone's signal. For example, there's a Tawkon app that lets users see when their phone has a weak signal.
Why should users care when their phone has a low signal?
Davis: People don't know those things. They don't realize that when the signal is weak, the phone puts out more of a signal to reach a tower and therefore puts out more radiation.
But radiation radio frequency is everywhere. We use cordless phones, baby monitors, and Wi-Fi, so we can never really get away from it. Can cell phones be the only point of concern?
Davis: No, the world is full of radiation. It's not that radiation is bad. But we need to understand it better and be more sensible about what kind of exposure we put ourselves through.
With cell phones in particular, we need to think twice about using them as an electronic pacifier for children. Children have thinner skulls that are more susceptible to radiation penetration. So if you let a child play with a phone, keep it disconnected [from Wi-Fi and the cellular network] so it's not putting out radiation. There are some simple common-sense things we can do.
Consider also that baby monitors use the same 2.4GHz frequency as many cell phones. So if you're going to use one, put it a good distance from the baby. And put the [Wi-Fi] router away from your sleeping area and your baby's room.
Why is it bothersome that the current standards used to test cell phones were developed in the 1990s?
Davis: Those standards applied to the early analog phones, when few people talked for long, and [they] relied on a test mannequin that stood more than 6 feet tall, weighed 220 pounds, and had an 11-pound head. Most users are smaller and talk much more now than was presumed at the time. Also, specific standards have never been developed for the young brain or toddlers.
The fact is that we are flying blind with respect to such technologies. We know that the brains of infants and children grow rapidly, but never in the past did they encounter the stimulation they now get from cell phones. What the long term impact of this may be remains a matter of speculation and concern, particularly given the ubiquity of the exposures.
In user manuals, most cell phone manufacturers include language that advises that your phone could exceed the FCC's 1.6-watt-per-kilogram SAR limit if you don't hold it at a short distance from your body while it is transmitting. What do you think of that?
Davis: That's stunning. Why are the companies doing that? It's really hard for me because there are a lot of extremists on both sides of the issue.
In the United States, some local and state governments, such as those in Maine, California, and San Francisco, have attempted to address the issue with legislation. But Congress hasn't spent much time talking about it. Do you expect the federal government to take any action?
Davis: We're making tremendous headway locally, but I think something is going to happen federally. It's just a mess right now, and we're close to a stalemate in the government--I mean, these guys can't even agree on who gets to go to the bathroom. But I think we're going to see progress at the FCC and FDA level on this issue. There's a lot going on in regard to this issue, and [the Obama Administration] is interested.
How do you respond to people that argue there can be no danger because the energy put out by phones is too low?
Davis: If energy were the required component for damage, that would make sense. The nonionizing radiation that cell phones use can impact sperm without a change in temperature and without breaking the ionic bonds that hold together the complex structure of DNA. So it can cause damage to DNA through other means. Also, cancer doesn't arise only after such damage occurs.
How do you react to people on the other end of the spectrum, who say that the evidence is clear and there is no question that radio frequency is harmful?
Davis: As with all things, the potential for harm depends on two major factors: the existing health of the person exposed and the toxicity of the exposure to which they are exposed. Though experimental studies consistently indicate that pulsed digital signals of microwave radiation emitted by today's cell phones increase some indicators of carcinogenic potential, there certainly appears to be a wide range of susceptibility to [cell phone radiation]. In other words, some people are exquisitely sensitive and most of us less so. Over time, the correct question is whether continued exposure, especially in the very young, will induce a host of damage in those who now show no such impacts.
Considering how little solid data we have and how short-lived the past experiments have been, it makes sense to err on the side of precaution until such time as research indicates that this precaution is not warranted.
In 2007, a large Danish study found no link between cell phones and cancer risk. That research has been used by those who say we don't have to worry. What's your opinion of that study?
Davis: There are major differences in the capacity of prospective studies, which [the Danish study] was, and case control studies, which most of the other studies on brain cancer and cell phone use have been. Prospective studies require huge numbers of people to be followed for long periods of time to yield useful results. For instance, some of the earliest findings of increased lung cancer came from prospective studies of millions of people followed for more than 30 years. Yet, the Danish research lacked the power to find a risk, because it studied a very rare outcome (brain cancer) in a relatively small population (about 500,000 people) for a relatively short time period (about 10 years).
Also, there were major problems with the definition of the study population (less than 5 percent of the Danish population) and very few of them used [cell phones] for long periods of time. They excluded those who arguably may have been the heaviest users, such as sales personnel, realtors, brokers, and others for whom cell phones are now essential tools of their work and often are used for hours every day. Finally, almost all funding for this study came from industry.
What about the Interphone study, which found a link between long-term cell phone use (10 years or more) and increased brain cancer risk?
Davis: An editorial that came out with the Interphone study said that if one looks solely at epidemiological data alone when assessing cell phones and increased brain cancer risk, the jury is still out. But when one includes the growing and robust experimental literature on the damaging capacity of cell phone radiation, combined with epidemiological studies of long-term users that consistently find increased brain tumors, there are solid indications of risk. The majority of the Interphone researchers share my concerns about children.
Now the good news from that study is that if you give cells melatonin, you can reverse and prevent the damage from cell phone radiation. So even if you've been keeping your phone in your pocket for eight years, and you've been using it for eight hours a day, get it out of your pocket and start reducing your use.
The exciting work in cancer today is that DNA damage does not necessarily lead to cancer. You get DNA damage all the time, from sunlight and oxygen, and you do not get cancer. It's the cumulative integrated dose that's an issue. But when you stop the exposure to that agent, which in this case is pulsed radio frequency signals, then your body's natural repair processes will kick in. People like to put their heads in the sand and say that they've been using a phone for eight years, so they're screwed. That's not true.
The debate is largely focused on brain tumors? Is that right?
Davis: A brain tumor is a tragedy for the person and the family, but brain cancer is not the only thing we should be thinking about here. And I'm very concerned because if that's the way the debate is framed, we'll be having that debate for another 20 years. We have to be smarter than this. We should have by now learned from our history and [from] work like this that we did with other agents, like tobacco.
Why do you think people are resistant to the idea of a possible danger?
Davis: I understand it. I mean, they call it a "crackberry" for a reason. There is an addictive property to these devices, and I qualify because I use a cell phone too. And these devices have become essential; they play a positive role in society.
In your book, you wrote that the scientific community has censored research that shows cell phones could be harmful. Where is the censorship coming from?
Davis: I've spent more than three decades in major research institutions, and we need money to do research. And if you definitively solve a question, then you're finished.
You talked a lot about the industry working to refute any studies that show a link. Can't there be some industry researchers who are considering the issue fairly?
Davis: Yes, I know there are. And they're going to win. People are not going to give up their cell phones, but they have to make them in a safer way and have safer designs for towers.
The CTIA has maintained that cell phones are safe and it points to studies that support its position. The organization also has opposed legislation regulating SAR warnings. How do you respond?
Davis: The keeps saying what they've said since 1993, which is that studies conclusively show that there's nothing to worry about. Well, let me tell you something: They do not conclusively show that. The few independent studies that are out there indicate that there's a problem. Most of the other studies have been sponsored by industry.
Would you ever trust a study funded by the industry?
Davis: Sure, if there was a total firewall.
The CTIA also points to government Web sites that show little risk. For example, the FDA's Web site says, "The weight of scientific evidence has not linked cell phones with any health problems," while the FCC's site says, "No scientific evidence establishes a causal link between wireless device use and cancer or other illnesses." Do you understand that some people will consider that enough proof?
Davis: But those Web sites are also saying, "If you're concerned, here's what you can do." That's been a sea change, and it's a testament to the flexibility of the government that they're no longer saying everything is fine and dandy. Even the American Cancer Society Web site has changed.
Do you think choosing a phone with a lower SAR is a good idea? The FCC's site used to make such a recommendation, but it changed that guidance last year.
Davis: I don't think it's a bad idea, but I don't think it's a guarantee. No matter how low the SAR is, if you keep the phone next to your head for six hours a day, you're still going to get exposure that you're better off not having. But all things being equal, lower would be better, but not enough.
I've had many readers ask whether Bluetooth headsets are safe, because they also put out radiation. Are they?
Davis: Bluetooth devices significantly reduce radiation--probably several thousand fold--and can be safe if they are used without the phone being kept on and in the pocket. The peak radiation exposure occurs in the moment you first click to answer the phone. That's when phones should never be held right next to the brain.
How do you think the debate will progress in the next few years?
Davis: I think that in 20 years we'll look back on phones in the same way we look back on cars and alcohol. They have valuable functions in society, but when misused they can kill you. And even when used in an ignorant manner, they can cause harm, whether it's a car crash from distracted driving to a long-term effect on hearing, like tinnitus.
Will we ever really find an answer?
Davis: It seldom gets that way, even with tobacco. Science isn't just done for practical reasons. It's done because we're always in search of some greater truth. We will always have a need for scientific research on many important topics. This is just one of them. There's no question about that.
Could you be wrong?
Davis: I don't think so. Could I be wrong about the extent? Perhaps. But that doesn't matter. The fact is, what I'm advocating isn't that hard. I'm not telling people to stop using their phones. That's not going to happen. But I feel like I'm watching an epidemic in motion. If we do not make major changes in the way that we use phones today, I fear we will be suffering consequences for generations. What I think needs to be done isn't that hard, and I know there are safer technologies out there.
[Editor's note: Though a few follow-up questions were submitted via e-mail, the majority of this interview was conducted over the telephone. For more information, see CNET's cell phone radiation charts.]