Are cell phones safe? The verdict is still out

Bruce Stutz, former editor in chief of Natural History, explains the latest research on cell phone safety in this reposting from Yale’s E360 online magazine.

While some studies have suggested that frequent use of cell phones causes increased risk of brain and mouth cancers, others have found no such links. But since cell phones are relatively new and brain cancers grow slowly, many experts are now recommending taking steps to reduce exposure.

Does your cell phone increase your risk of brain cancer? Does it affect your skin or your sperm viability? Is it safe for pregnant women or children? Should you keep it in your bag, on your belt, in your pants or shirt pocket? Should you use a hands-free headset? Are present cell phone safety standards strict enough?

You don’t know? You’re not alone.

Are Cell Phones Safe? Too Early to TellWith some 4 to 5 billion cell phones now in use worldwide and hundreds of studies seeking evidence of their health effects published in peer-reviewed journals over the last 10 years, there’s precious little scientific certainty over whether cell phones pose any danger to those using them. For nearly every study that reports an effect, another, just as carefully conducted, finds none. All of which leaves journalists, consumer advocates, regulatory agencies, politicians, industry spokespersons, and cell phone users able to choose and interpret the results they prefer, or ignore the ones they don’t.

Do you, for instance, cite the studies that report adverse effects on sperm viability and motility, due to exposure to cell phone radiation or the studies that showed no “” or mixed “” results?

Do you cite the 2001 study that found increased incidence of uveal melanoma (a cancer of the eye) among frequent cell phone users, or the 2009 study by the same authors that, in reassessing their data, found no increase?

Do you cite the Israeli study that found an association between salivary gland cancer and heavy use of cell phones or the Swedish study that found none?

Do you parse the data and report only those results that have found effects “” no matter how small “” without citing studies that found no effects? In its much-cited review of cell phone studies, the Environmental Working Group has done just that, reporting, for instance, that “a study from the University of California, Los Angeles, found a correlation between prenatal exposure to cell phone radiation and behavioral problems in children.” But the group left out the study’s very next sentence acknowledging that the association may be “noncausal and may be due to unmeasured confounding.”

The effects of cell phones have proven difficult to assess because they are relatively new, the way and the amount they’re used continues to evolve, and the problems that cell phones might cause are hard to detect. Brain cancers, for instance, are very rare cancers. They affect only some 18 out of every 100,000 people. But the fact that there’s been no recent increase in the numbers may be meaningless with regard to cell phone use since brain cancers are very slow-growing.

Cell phones produce “non-ionizing” radiation, which, unlike X- or gamma rays, doesn’t damage DNA by stripping away electrons from molecules in cell tissue. Radiofrequency energy does, however, produce heat and, at high enough levels, can damage cell tissue. This, in the late 1990s, prompted the U.S. Federal Communications Commission (FCC) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in Europe to set limits on cell phones’ Specific Absorption Rate (SAR) “” the measure of the amount of radiofrequency energy a cell phone user absorbs “” at, respectively, 1.6 and 2.0 watts per kilogram. The question remains, however, whether these standards are sufficient to protect against long-term exposures and whether the buildup of heat in cell tissues is more damaging where there’s less blood flow to dissipate it, such as the outer ear, brain, skin, or testes.

The exposure standard has been the subject of Congressional hearings. Consumer groups have warned that children may be more susceptible to radiofrequency heating effects than adults. U.S. Congressman Dennis Kucinich introduced a bill for a federal research program on the effects of cell phone radiation that also calls for a label warning users about potential links between long-term use and cancer.

Last month, San Francisco passed a “Cell Phone Right-to-Know” law that requires manufacturers to post in stores each cell phone’s Specific Absorption Rate. In response, CTIA-The Wireless Association, which represents the wireless communications industry, filed suit July 23 in U.S. District Court in San Francisco to block enforcement of the new law. It cites the U.S. Food and Drug Administration’s (FDA) statement that “the weight of scientific evidence has not linked cell phones with any health problems.”

So far, the National Cancer Institute stands by the FDA. And neither the FCC nor the ICNIRP has recommended any changes in their present standards until there’s clear scientific evidence to demonstrate they need changing.

That kind of clarity may be a long way off.

Take, for example, the findings released in May of INTERPHONE, the largest and longest study ever conducted on whether “” and by how much “” cell phone use increases the odds of developing brain cancer. Carried out by the International Agency for Research on Cancer “” at a cost of some $25 million and nearly 10 years in the making “” the study involved roughly two dozen scientists and research teams from around the world and some 10,000 patients and cell phone users from 13 countries. The study’s epic scope, however, only made its meager conclusions seem all the more unsatisfying.

“Overall, no increase in risk of glioma [a cancer of the cells that protects the brain’s neurons] or meningioma [tumors that develop in the tissue that surrounds the brain] was observed with use of mobile phones,” the study concluded. “The possible effects of long-term heavy use of mobile phones require further investigation.”

And yet even these modest claims proved contentious. The study scientists themselves recognized problems in the methodology: While they had good data on the participants’ tumor and cancer histories, they had very suspect data on their cell phone usage. Participants’ recall of how often and how much they talked on their cell phones, when checked against their actual cell phone records, in some cases proved very unreliable. The matching of patients with control subjects also turned out to be problematic. Should controls include only those who never used a cell phone and exclude those who’d used one only infrequently? While the distinction may seem insignificant, such selection biases can wreak statistical havoc. The analysis using the first group, for instance, resulted in the somewhat astonishing finding that regular users of cell phones had a reduced risk of developing glioma.

No one was surprised, therefore, that divisions appeared over interpreting the study’s results. These delayed its release for four years. The raw data, in fact, showed that “long-term heavy use” “” that is, talking on a cell phone for 30 minutes a day for 10 years “” increased the odds of developing glioma by 40 percent. The question was whether this result was subject to the same selection bias as that which strangely showed a reduced risk among regular users. The final decision was that the findings with regard to the “effects of long-term heavy use” were, while worth “further investigation,” too unreliable to conclude they represented a clear and irrefutable increased risk.

While the risk of any individual developing glioma would still be small, a 40 percent increase could still mean some thousands more new cases in the U.S. each year. And gliomas account for nearly half of all childhood tumors.

The question for the INTERPHONE scientists was whether this finding was real or the result of flawed data?

As Finnish researcher Dariusz Leszczynski of Helsinki’s STUK-Radiation and Nuclear Safety Authority, put it, the study’s combination of reliable and flawed information resulted in a “scientifically unreliable and non-informative result.”

“What it all means,” Leszczynski concludes, “is that after 10 years of research and millions of Euros used for it we are still in the starting point [his emphasis] and do not have the answer whether, or whether not, mobile phone radiation could cause brain cancer.”

Christopher Wild, director of the International Agency for Research on Cancer, acknowledges that most of the study’s participants, even the heaviest users, were not frequent mobile phone users by today’s standards. The criteria for a “regular” user was someone who made from one call a week to 25 calls a day, but no one in the study talked for more than half an hour a day. On the other hand, the study doesn’t take into account that people now often text rather than talk, and many more use hands-free headsets.

Ten years of use may not be a legitimate time frame to establish any causal links to such slow-growing cancers. And if there is a risk, does it continue to increase beyond 10 years of usage, and by how much? This would especially be a concern for those who began using cell phones when they were children, as is now frequently the case.

New epidemiological studies now underway might prove more elucidating. They include COSMOS, a United Kingdom study that will follow for 20 to 30 years some 350,000 cell phone users from the UK, Finland, Sweden, Denmark, and The Netherlands, and that will use actual cell phone records for their database. Another study, MOBI-KIDS, is a European Union project in 13 countries that over five years will compare the cell phone usage of some 2000 young people, ages 10 to 24, with brain tumors to the same number of healthy controls.

Are there alternatives to epidemiological studies?

Studying animals exposed to cell phone radiation has proven difficult, especially when it comes to controlling doses of radiation which, in the case of cell phones, are small; the response of animal cells at low doses may not reflect the response of human cells.

Recent in vitro studies “” that is, studies on cultured cell tissue “” have focused on whether radiofrequency radiation might interfere with the DNA repair process and cause damaged DNA to accumulate. So far, some studies have found damage while others have not. With so much uncertainty as to what exactly causes the disruption of cell processes, it’s difficult to compare one study with another. The same uncertainty has been true regarding the few studies on sperm “” of concern because many men tend to keep their cell phones in their front pants pockets.

Leszczynski and others point out that present SAR standards don’t necessarily take into account how cell phones are actually used. While our brain may be exposed to the allowable amount of radiofrequency radiation, our bodies and our skin may be getting more than the phone’s advertised dose of radiofrequency radiation. A hands-free device can reduce exposure to the head, but if you still keep your phone in your shirt pocket, your body’s still being exposed.

In the meantime, nearly everyone seems to agree that it’s worth putting the precautionary principle into play; that is, reduce your exposure as best you can. The radiofrequency radiation falls off quickly the farther your cell phone is from your body. Look for a cell phone with a low SAR. Don’t keep your cell phone in your pocket. Use a hands-free device. Text rather than talk. And while the cancer risks are unknown, the risks from using your cell phone while driving are pretty clear.

Bruce Stutz, writing for Yale E360.

If you are interested in reading more on this subject, my cousin Louis Slesin, runs “Microwave News: A report on non-ionizing radiation,” which Fortune magazine has called “the most authoritative journal on ELF fields and health” and which Time magazine has called meticulously researched and thoroughly documented.

Related Post:

14 Responses to Are cell phones safe? The verdict is still out

  1. Colorado Bob says:

    Dimmer view of Earth

    When Stanford climate scientist Christopher Field looks at visual feeds from a satellite monitoring deforestation in the Amazon basin, he sees images streaked with white lines devoid of data.

    The satellite, Lansat 7, is broken. And it’s emblematic of the nation’s battered satellite environmental monitoring program. The bad news: It’s only going to get worse, unless the federal agencies criticized for their poor management of the satellite systems over the past decade stage a fast turnaround. Many, however, view that prospect as a long shot.

    “I would say our ability to observe the Earth from space is at grave risk of dying from neglect,” said Field, director of the Department of Global Ecology at the Carnegie Institution for Science at Stanford University.

    Inez Fung, a noted climatologist at UC Berkeley, was shocked as she scanned a recent federal report warning of impending gaps in the country’s ability to monitor Earth from space.

  2. Chad says:

    I agree with Burk. Not only is there little evidence of harm, but there isn’t even a highly plausible mechanism FOR there to be harm. The microwave radiation from a cell phone is lower in energy than the thermal background noise. The infrared photons emitted by your own body are higher in energy!

  3. mark says:

    Should I worry about my cell phone if I’m already wearing tight underwear?

  4. jim says:

    This post seems pretty far off topic for Climate Progress.

    [JR: I’ve done 2 posts on this in 4 years. I cover interesting environment, energy, and related public health and political issues I think readers should know about. Maybe 1% aren’t directly related to climate or cutting GHGs.]

  5. Chris says:

    I agree with jim.

  6. gilgit says:

    Strange topic to see here. I know you sometimes venture out of the strict Global Warming topic to broader environmental topics, but still think it is strange to waste time on this topic.

    The reason why I think this topic is a waste of time is because there doesn’t seem to be any kind of obvious threat, no mechanism to cause problems, and no credible studies showing a strong correlation.

    Much of this website talks about using good science to figure out what is happening and common sense to judge which worse cases need to be countered against.

    The current understanding of science says that cell phones can’t cause cancer and other medical problems. If the science is wrong, even then the effect must be small otherwise we would have already seen it more clearly in early studies.

    The Respectful Insolence blog at has reports on cell phone dangers on occasion:

    I’d especially point to the part of the first article where they found that cell phones provide a protective effect. Whenever I see something like that I always assume that there is no effect at all.

    When you study something with no effect, you will always find regions with small negative and positive effects just by chance. I strongly suspect that is what is going on here.

    But it is always possible that the current science is wrong. But even in that case, the effect must be very small or we should have seen more obvious signs of it already.

    I wouldn’t have said anything, but many of the deniers trying to destroy the world point to very small effects and try and claim that these effects are what we should be concentrating on instead of the obvious problems. I know that your motives were different, but I still wanted to speak up.

    [JR: Some studies in smoking through the 1950s suggested little or no health impacts, so I don’t think this is a strong point for you. You last paragraph I don’t get at all.]

  7. Larry Gilman says:

    Although the cancer connection is highly debated, it is well-established that cell-phone type radiation alters human EEG (brain waves) in real time: see Intern. J. Neuroscience, 113:1007–1019, 2003 free at Also that there are affects on sleep patterns — Neurosci Lett. 1999 Nov 19;275(3):207-10, available at . See also the brief review by Lin, JC, Human EEG and Microwave Radiation from Cell Phones, IEEE Microwave Magazine, June 2004, 34-38. (For those of you who aren’t electrical engineers, be it known that you just can’t get any more respectable or mainstream than the IEEE.) These are merely exemplary references; studies are numerous. So, to be blunt in the vernacular, cell phones are doing stuff to our minds that we don’t understand. We don’t understand if the stuff that they’re doing matters, or how much it matters if it does, or how it happens. Not very reassuring — unless you’re of the mind that absence of evidence of harm is evidence of absence. Which it ain’t.

    Children, for sure, should not be using cell phones, with all the unknowns (and the knowns!) about the effects — children have thinner skulls and smaller heads, which leads directly to much greater exposure of the brain. France is leading the curve on this one:

    The reassuring blah-blah one sees sometimes about we “lack a mechanism” for harm sounds skeptical and tech-minded but actually reflects prescientific thinking. If you an observe an effect, you ferret out its mechanism: you never deny an observation simply because you haven’t yet figured its mechanism. Not if you’re thinking like a scientist, anyway. To view it from another angle, there is no clear mechanism for EEG effects from cell phone radiation, but they exist: so to sweep aside the possibility of other biological effects (e.g., cancer) because we don’t know a mechanism for those yet, either, would be not only illogical but imprudent.

    Besides all which, mechanisms of harm are not difficult to postulate, once we de-obsess on the fact that the microwave intensities involved are far too low to literally cook tissue: see .

    Cautionary principle, anyone?


    [JR: Thanks for this. The Yale e360 piece was quite even-handed, I thought. Surprised it engendered such a reaction, among some. Many studies have been done and some raises legitimate concerns.]

  8. Tim says:

    Let me chime in with Chad and gilgit: there is real evidence of harm caused by cell phones and there is no plausible mechanism for such harm to occur. C’mon, the frequencies used are not all that different than those used by UHF broadcast television for decades. If cell phones are harmful, the risks must be pretty low.

  9. Tim says:

    oops, that should have been: … no real evidence …

  10. Ben S says:

    It’s not like anyone uses cellular devices to make phone calls nowadays..

  11. david ehm says:

    More information about the biological effects of non-ionizing radiation from wireless technology is coming out every day. Enough is not being done by cities, counties, states and the Federal Government to protect us from the potentially devastating health and environmental effects. Through the 1996 telecommunications act the telecoms are shielded from liability and oversight. Initially cell phones were released with no pre-market safety testing despite the fact the Government and the Military have known for over 50 years that radio frequency is harmful to all biological systems (inthesenewtimes dot com/2009/05/02/6458/.). Health studies were suppressed and the 4 trillion dollar a year industry was given what amounts to a license to kill.
    On it’s face, the 1996 telecommunications act is unconstitutional and a cover-up. Within the fine print city governments are not allowed to consider “environmental” effects from cell towers. They should anyway! It is the moral and legal obligation of our government to protect our health and welfare? Or is it? When did this become an obsolete concept? A cell tower is a microwave weapon capable of causing cancer, genetic damage & other biological problems. Bees, bats, humans, plants and trees are all affected by RF & EMF. Communities fight to keep cell towers away from schools yet they allow the school boards to install wi fi in all of our schools thereby irradiating our kids for 6-7 hours each day. Kids go home and the genetic assault continues with DECT portable phones, cell phones, wi fi and Wii’s. A tsunami of cancers and early alzheimer’s await our kids. Young people under the age of 20 are 420% more at risk of forming brain tumors (Swedish study, Dr. Lennart Hardell) because of their soft skulls, brain size and cell turn over time. Instead of teaching “safer” cell phone use and the dangers of wireless technology our schools mindlessly rush to wireless bending to industry pressure rather than informed decision making. We teach about alcohol, tobacco, drugs and safe sex but not about “safer” cell phone use. We are in a wireless trance, scientists are panicking while young brains, ovaries and sperm burns.

  12. Larry Gilman says:

    Apologies: the links fail in my earlier post on cell phones and EEG. Delete the terminal right-hand parenthesis in the URL bar and they’ll work.

    This topic has been snubbed as off-topic for ClimateProgress, but I think it addresses an important theme: prudent decision-making in the midst of scientific uncertainty. With cell-phone health effects, we are on a different point of the continuum of uncertainty than we are when discussing climate change. With climate, we have extremely low uncertainty that the thing is happening, and harmful, and that human activities are causing it: yet there is a high-uncertainty realm in climate change, too, namely in the timing and extremity of certain future events (ice-sheet breakdown, etc). Cell-phone health effects are an intriguing case because here is another realm where the stakes run high — hundreds of millions of people are being exposed — and where experts duel over details and conflicting studies. Questions about possible cell-phone harm are often dismissed with an edgy, angry scorn directly proportional to the lifestyle disruption (and lost profits) that would be entailed by verified bad news.

    The differences and similarities between the cases are worth thinking about. There is not enough evidence of cell-phone harm to call those who deny such harm “denialists”: there is room for authentic skepticism on both sides. Yet there is an obvious motive for downplaying the possibility of harm: we would all prefer that cell phones were perfectly safe for all users, at all times of life, at all rates of use. That would be very nice. It may even be true. But it may not be true, and blustering won’t make it so.

    Most of us, thanks to Carl Sagan, are familiar with Marcello Truzzi’s dictum that “extraordinary claims require extraordinary evidence.” I propose a variant, to be applied to a wide range of issues: climate change, genetic engineering of foods, nuclear power, tobacco risks, low-level ionizing radiation health effects, cell-phone health effects, bisphenol A in our bodies ( ), geoengineering, and all other issues in which risk, profit (or other forms of power), scientific uncertainty, and values intersect:

    “Reassurances from interested experts require extraordinary evidence.”

    Here the word “interested” bears its legalistic sense, i.e., “having involvement, not impartial or disinterested.”

    One should extend the Truzzi B principle to all reassuring statements by all interested expert or insider spokespersons, e.g. for industries, governments, militaries, churches, police departments, oil companies. Elementary intellectual hygiene.

  13. Eric says:

    The furnace in my house emits heat radiation, as does my oven. Should I be worried they will give my kids cancer?

  14. Larry Gilman says:

    Eric, that is a really great question. I love the way you dissect the scientific and colloquial meanings of the word “radiation”, quickly balance the conflicting relevant research studies regarding microwave emissions from cell phones, touch insightfully in passing on the politics of popular fear and expert reassurance — all while pretending to be a lazy sneerer! Brilliant!

    To answer your question, the infrared radiation from your oven and furnace is, of course, dangerous, but the mechanism of harm with excessive exposure is the thermal burn, not carcinogenesis . . .