Field of Science

The top five cold remedies that do not work

A cure for the cold, from ThadGuy.com
One of my daughters caught a cold last week, and now she's given it to me. We’re giving ourselves the best treatment known to science: rest. But to judge from the products offered at our pharmacies, you’d think there were dozens of options to treat a cold. In local pharmacies and in the medicines aisle at my local grocery store, I’ve found row after row of colorful packages, claiming to relieve cold symptoms, shorten the duration of the common cold,” and more. 

Some of these medications actually do treat symptoms, but none of them cure a cold. But mixed among them—sometimes side-by-side with real medicines—I found several products that don’t work at all. 

How can a drug manufacturer get away with this? Simple: the products that don’t work are either supplements or homeopathic products. The manufacturers of both these types of “medicines” have successfully lobbied Congress to pass laws that exempt them from FDA regulation. Supposedly they aren’t allowed to make direct claims to cure or treat disease, but unless you read the wording on their packages very carefully, you’d never notice. (Note to older adults: bring your reading glasses to the pharmacy section!) 

Most important for consumers: if a treatment says it’s homeopathic, then its ingredients do not have to be shown effective. “Homeopathic” simply means that the ingredients are listed on the Homeopathic Pharmacopoeia, a list maintained by homeopaths themselves. And if it contains supplements or vitamins, they too are exempted from regulation by the FDA, under a law known as DSHEA

So next time you go searching for something to take for your cold, or for your child’s cold, here are the top 5 cold remedies you should not buy:

1. Zicam is a zinc-based remedy. Zinc is tricky, because there is some evidence to suggest that taking zinc right at the onset of a cold might shorten its duration a little bit, from 7 days to 6. But as Dr. Terence Davidson from UC San Diego explained, if you look at the more rigorous studies, the effect vanishes. Zinc turns out to have some worrisome side effects, too. Zicam's nasal spray and gel versions were linked to a serious loss of the sense of smell (anosmia), which led the FDA to issue a warning letter in 2009. Zicam responded by withdrawing the product for a time, but their website now says “A clinical link between the Zicam® products and anosmia was not established.“ Strictly speaking, this is correct, but there have been published reports suggesting a link, such as this one from 2009.

Zicam’s website makes the misleading claim that “All of our Zicam® products are regulated by the FDA.” This is a common ploy of homeopathic drugmakers, claiming the FDA regulates them because the FDA could step in (as they've already done with Zicam) if consumers are being harmed. Unlike real drugs, though, Zicam has not been evaluated by the FDA for effectiveness or safety.

2. Airborne. You can find this in the cold remedy section many pharmacies (I did), but Airborne doesn’t cure anything. It’s a cleverly marketed vitamin supplement with no scientific support for any health benefits. How do they get away with it? Actually, Airborne paid $23 million back in 2008 to settle a class-action lawsuit over its advertising. They had been calling Airborne a “miracle cold buster.” According to the Center for Science in the Public Interest’s David Schardt, 
“Airborne is basically an overpriced, run-of-the-mill vitamin pill that’s been cleverly, but deceptively, marketed.”
After the lawsuit, Airborne modified their packaging, which now claims only that it “helps support your immune system.” This is one of those vague claims that supplement makers love, because it doesn't really mean anything. Airborne's products also now include a disclaimer that
 “These products are not intended to diagnose, treat, cure, or prevent any disease.”  
So what the heck are they doing in the “cold medicines” section of the store?

3. Coldcalm is a homeopathic preparation sold by Boiron, one of the world’s largest manufacturers of homeopathic remedies (including Oscillococcinum, an almost laughably ineffective flu remedy). It claims on the package to relieve cold symptoms. What’s in it? A dog’s breakfast of homeopathic ingredients, including belladonna, about which NIH says
Belladonna is UNSAFE when taken by mouth. It contains chemicals that can be toxic.” 
Another ingredient is pulsatilla, which “is highly toxic, and produces cardiogenic toxins and oxytoxins which slow the heart in humans.” Neither belladonna nor pulsatilla relieves cold symptoms.

Being homeopathic, these ingredients are highly dilute, but I think I’ll pass on Coldcalm.

4. UmckaUmcka is another homeopathic preparation that claims to “shorten the duration of common cold” and “reduce severity of cold symptoms.” Sounds pretty good—if only it were true. Umcka’s active ingredient is a plant extract called pelargonium sidoides, an African geranium. Interestingly, there have been a few experiments on this extract, some of which showed a small positive effect. However, a review of these studies reported that their quality was “very low," that all of them were conducted by Umcka itself, and that all of them were conducted in the same region of Russia. And remember: homeopathic preparations are so dilute that they contain little, and sometimes none, of the active ingredient.

5. Antibiotics. Okay, these are real medicine, and you can’t buy them over the counter at your pharmacy. But Americans take them in huge quantities to treat the common cold. The problem is, antibiotics don’t work for colds.

When my daughter told her friends she had a cold, they wanted to know why she didn’t go to the doctor. Of course, doctors can’t do anything about a cold, and going to a doctor’s office just puts other patients at risk. My daughter knows this. But her friends were astonished to hear that we never take her to the doctor for a cold. It turns out that most of them had been to doctors many times for colds, often coming away with a prescription for antibiotics. 

Antibiotics treat bacterial infections, not viruses. Taking antibiotics unnecessarily can be bad for you: besides wiping out your gut flora, it increases the risk that bacteria will develop drug resistance. Perhaps if we changed the name to "antibacterials," doctors would stop prescribing them for viruses.

I found Zicam, Airborne, Umcka, and Coldcalm for sale at Walgreens and Walmart. CVS and RiteAid don’t carry Umcka (good for them!) but do sell the others.

When you get a cold, you develop immunity to it and you won’t catch it again.We keep getting colds because they're caused by more than 100 different viruses, most of them nasty little buggers that continually circulate in our population. Each time you catch a cold, you’re getting a brand new one. The only consolation is that once you’re over it, you won’t get that one again.

So if you get a cold this winter, save your money. Stay home, rest and drink plenty of fluids. And I have it on good authority that there is one treatment for the common cold that’s inexpensive, widely available, and really, really works: chicken soup.


“Shocking Report” on flu vaccines is neither shocking nor correct

Flu season is coming, and once again it’s time to get your flu shot (or snort, if you prefer FluMist). It’s not perfect, but the vaccine is your best protection against the influenza virus.

So I was surprised to stumble upon an article titled “Johns Hopkins Scientist Reveals Shocking Report on Flu Vaccines,” which popped up on an anti-vaccine website two weeks ago. Johns Hopkins University is my own institution, and I hadn’t heard any shocking new findings. I soon discovered that this article contained only a tiny seed of truth, surrounded by a mountain of anti-vaccine misinformation. Most of it focused on a report published in early 2013 by Peter Doshi, a former postdoctoral fellow at Hopkins.

First, as Snopes.com has already pointed out, Doshi is not a virologist or an epidemiologist, but rather an anthropologist who studies comparative effectiveness research. He never conducted influenza research at Hopkins. (He’s now an Assistant Professor at the University of Maryland’s School of Pharmacy.) Second, Doshi’s 2013 article was an opinion piece (a “feature”), not an original research article, and it did not report any new findings. Third, it is highly misleading to suggest (as the anti-vax article’s title does) that Doshi somehow represents Johns Hopkins University. At Johns Hopkins Hospital, the flu vaccine is required of all personnel who have contact with patients, as a good-practices effort to minimize the risk that a patient will catch the flu from a caregiver.

But what did Doshi’s article say? Even though it isn’t new, why are the anti-vaccine sites recycling it? His central argument is this:
“The vaccine might be less beneficial and less safe than has been claimed, and the threat of influenza appears overstated.”
Let’s look at this statement. It’s almost obviously true: one only has to find a few overstated claims about the risks of flu, which isn't hard to do. But it’s also completely consistent to state that the vaccine is enormously beneficial and that the threat of influenza is very serious. See how that works? 

Doshi uses this slight-of-hand to suggest that the vaccine may not be beneficial at all. He never says this outright—instead, he just questions, again and again, whether the precise percentages reported in published studies are accurate. For example, he makes a big deal of a CDC announcement in 2013 that the vaccine’s effectiveness was only 62%. He casts doubt with phrases like 
“the 62% reduction statistic almost certainly does not hold true for all subpopulations”
which is almost certainly true, but is meaningless from the point of view of public health. Of course the vaccine doesn’t have the same effectiveness in everyone. The point is that it works most of the time. 

Doshi cites another study that showed a clear benefit for the flu vaccine, only to cast doubt on it with this argument: 
“No evidence exists, however, to show that this reduction in risk of symptomatic influenza for a specific population—here, among healthy adults—extrapolates into any reduced risk of serious complications from influenza such as hospitalizations or death in another population.”
Again, Doshi’s argument doesn’t prove that the original study was wrong, only that it doesn’t apply to everyone. But Doshi’s motivation, as evidenced by the relentlessly negative slant of his entire article, seems to be to convince people that the flu vaccine is bad.

Not surprisingly, the anti-vaccine movement has embraced Doshi (for example, here and here). And unfortunately, he seems to have accepted their acclaim: in 2009, he spoke at an anti-vaccine conference hosted by NVIC, a notorious (and misleadingly named) anti-vaccination group.

Perhaps even more disturbing is that Doshi signed a petition arguing that the HIV virus is not the cause of AIDS, joining the ranks of HIV denialists. He signed this statement while still a graduate student, so I contacted him to ask if he still doubted the link between HIV and AIDS. I also asked him if he supports flu vaccination, if he agrees with the anti-vaccine movement's use of his statements, and if he believes the flu is a serious public health threat.

On the question of signing the HIV/AIDS petition, Doshi responded that "Seeing how my name was published and people have misconstrued this as some kind of endorsement, I have written the list owner and asked for my name to be removed." (He declined to state directly - and I gave him the chance - that he agrees that the HIV virus causes AIDS.)

As for the flu itself, Doshi says "I don’t agree with CDC’s portrayal of influenza as a major public health threat." So he and I have a serious disagreement there. I asked if he agrees with the anti-vaccinationist who are using his writings to claim that the flu vaccine is ineffective, and he replied that while "ineffective" is "too sweeping," he has found "no compelling evidence of hospitalization and mortality reduction in [the] elderly."

Doshi’s argument against the flu vaccine boils down to this: the vaccine is much less than 100% effective. This is undeniably true, and the research community makes no secret of it. In fact, many of us have repeatedly called for more research into better vaccines, in the effort to create a vaccine that is not only more effective, but that (like most other vaccines) only needs to be taken once for lifetime immunity. We’re just not there yet. Meanwhile, though, the annual flu vaccine is usually effective: a recent study showed, for example, that it reduced children’s risk of ending up in a pediatric intensive care unit by 74%.

So get your flu shot (or snort) now, before flu season hits, because it takes a couple of weeks for your body to develop immunity. By getting immunized, you’ll not only increase your chances of getting through the winter flu-free, but (because you won’t spread the flu to others) you might also save someone whose immune system would be overwhelmed by influenza. 

Should the government allow scientists to create new super-viruses?

Let's suppose a bunch of scientists proposed to take one of the most infectious human viruses—influenza, say—and turn it into a super-bug. Is this a good idea?

Or to put it another way: should scientists be artificially mutating viruses so that they have the potential to become a worldwide pandemic?

Right about now you might be asking: is anyone actually doing this, and if so, what on earth are they thinking?

And yet, several of the world's most prominent influenza researchers have been engaged in exactly this enterprise for several years now. They call their work "gain of function" experiments, because they manipulating viruses to give them new (and very dangerous) functions.

I wrote about this last year, after a group led by Ron Fouchier at Erasmus Medical Center in the Netherlands and Yoshihiro Kawaoka of the University of Wisconsin announced, in a letter to Nature, that they were going to create a new strain of H7N9 influenza virus that had the potential to turn into a human pandemic. Sure enough, just a few months later, Fouchier published results showing they had done just that, although they reported that their newly engineered strain had only "limited" transmissibility between ferrets (the animal they used for all their experiments).

Fouchier and Kawaoka had already done the same thing with the deadly H5N1 "bird flu" virus, causing a huge outcry among scientists and the public. As reported in Science magazine almost three years ago, Fouchier admitted that his artificially mutated H5N1 was "probably one of the most dangerous viruses you can make."

And yet he did it anyway—and then did it again, with H7N9.

Many other scientists were and are extremely concerned about these experiments, which some of us consider dangerous and irresponsible. This past July, a large group of scientists known as the Cambridge Working Group (of which I am a member) released a statement calling for a hiatus, saying:
"Experiments involving the creation of potential pandemic pathogens should be curtailed until there has been a quantitative, objective and credible assessment of the risks, potential benefits, and opportunities for risk mitigation, as well as comparison against safer experimental approaches."
Just two days ago, the U.S. government responded, announcing that it was going to take a serious look at whether creating these superbugs is a good idea. The Office of Science and Technology Policy (OSTP) is creating two committees to "assess the potential risks and benefits" of these experiments, particularly those involving the influenza, SARS, and MERS viruses.

Until the committees come up with recommendations, the government is halting any new funding for these experiments and asking for a voluntary "pause" on existing work.

Not surprisingly, Fouchier and his colleagues have argued that their work has benefits; that it has "contributed to our understanding of host adaptation by influenza viruses, the development of vaccines and therapeutics, and improved surveillance." Yet these arguments are tenuous at best. Fouchier and company have failed to show that the mutations they found in ferret experiments are likely to occur in the natural course of human outbreaks, which means that using their viruses for vaccine development would be a huge mistake.

And to claim that creating super-viruses in the lab will lead to "improved surveillance" is, frankly, laughable. Surveillance means getting out in the field and collecting samples from sick people. Gain-of-function laboratory experiments have basically nothing to do with surveillance.

Harvard's Marc Lipitsch has been one of the prominent voices arguing against this line of research, writing just last week that the scientific benefits of these experiments are very limited, for reasons detailed in his article. Lipitsch is also one of the founding members of the Cambridge Working Group.

According to the announcement from The White House, the first committee to evaluate the merit of these experiments will meet in just a few days, on 22 October. Meetings will continue throughout the winter, with recommendations expected sometime in the spring of 2015.

We have enough problems with influenza, and now with Ebola too, without scientists creating incredibly deadly new viruses that might accidentally escape their labs. Let's hope that the OSTP does the right thing and shuts down these experiments permanently.

How to stop Ebola: ban air travel from West African countries

Countries in which Ebola virus has appeared in the past.
I never thought I’d find myself agreeing with Louisiana governor Bobby Jindal. But this week, Governor Jindal called for a ban on air travel to the U.S. from the countries where the epidemic is present. He’s right: a flight ban is the best way to keep Ebola from spreading. 

In the world of infectious diseases, we often hear the phrase that the next epidemic is “one flight away” from the U.S. That’s truebut we don’t usually know where that flight will originate, so we can’t simply ban all flights to the U.S. from everywhere. With Ebola, though, we know the source: the epidemic is confined to Liberia, Sierra Leone, and Guinea. 

As the Ebola crisis has grown in West Africa, the need to stop its spread has grown ever more urgent. The number of cases is now over 20,000, and the CDC estimates that by January, Liberia and Sierra Leone will have 1.4 million people with Ebola infections. These are frightening numbers.

The Ebola virus has no treatment and no cure, although some promising research is under way (as I’ve written about previously). According to the WHO, the Ebola fatality rate is 50%. This makes it one of the deadliest diseases known to affect humans.

And now, alarmingly, Ebola has appeared in the U.S., in an airplane passenger who traveled from Liberia to Texas. This one individual has exposed as many as 114 others, all of whom are now being followed by the CDC.

In a press briefing yesterday, CDC Director Tom Frieden offered this reassurance:
We know how to stop outbreaks of Ebola.  In this country, we have health care infection control and public health systems that are tried and true and will stop before there's any widespread transmission.  The core of that, the way to stop Ebola in its tracks is contact tracing, and follow-up.”
Dr. Frieden is correct that we can stop an outbreak, if we can find everyone exposed and quarantine those who might be infected. But he dismissed the notion of simply banning travel: 
“Although we might wish we could seal ourselves off from the world, there are Americans who have the right of return.  There are many other people who have the right to enter into this country.”
I'm not arguing that we should “seal ourselves off from the world." (Nor, I suspect, is Governor Jindal.) We are arguing to seal off just three small countries in West Africa, until the epidemic passes. This would not be a difficult ban to implement and enforce. For Americans who wish to return from those countries, we can require a quarantine protocol, which the CDC already has in place at many airports. As Jindal said:
"How exactly would stopping the entry of people potentially carrying the Ebola virus be counterproductive? This seems to be an obvious step to protect public health in the United States.”
CDC Director Frieden also revealed yesterday that in the month of September, screening at airports in African countries has turned away 77 people who had signs of possible Ebola infection, including 17 in the month of September. Although Frieden used this example to illustrate the effectiveness of CDC’s screening program, it also shows that sick people are trying to board planes to the U.S. As the outbreak grows, it will grow increasingly difficult to keep all Ebola-infected passengers—who don't show signs of infection for several days—off those planes.


Director Frieden is correct that we can stop outbreaks of Ebola here, because we live in a modern country with good infection control systems. But prevention is better than control. So much as I hate to admit it, Bobby Jindal is right: we need a travel ban if we want to keep the Ebola virus out of the U.S.

Does a standing desk lengthen your lifespan?

Standing desks are all the rage lately. These desks allow you to stand up while working on your computer. Some standing desks can be raised and lowered, so you can alternate during the course of the day between sitting and standing. The principal argument for these desks is that they provide health benefits.

Proponents of standing desks claim, plausibly, that they give you more energy and improve posture. The CDC has found that standing desks (or “sit-stand” desks) reduce upper back and neck pain and improve moods. At Smithsonian.com, Joseph Stromberg reported that standing desks reduce the risk of obesity and type 2 diabetes. And a 2012 Australian study found that prolonged sitting increased the risk of death. In other words, standing up more and sitting less can help you live longer. All this makes me want to stand up right now.

The newest claim is that standing up lengthens your telomeres. If true, this would provide a mechanism to explain how standing up might lengthen your life. The new study, led by Swedish scientist Per Sjögren, appeared this month in the British Journal of Sports Medicine.

Telomeres are special DNA “caps” on the ends of everyone’s chromosomes. As we age, these caps gradually get shorter, and if they get too short, the cell dies. They function as a kind of molecular clock, telling a cell when it’s old. A substantial body of scientific evidence shows that if you can maintain telomere length, cells—and their owners—will live longer.

But how could merely standing more, or sitting less, shorten our telomeres? Being skeptical, I read the paper.

Here’s what Sjögren and colleagues did: several years ago, they conducted a study measuring the effect of exercise on weight, cholesterol levels, and a few other characteristics. That study included 101 people, all 68 years old. They randomly chose 49 people (14 men, 35 women) to study the effect of exercise on telomere length. They used blood samples taken 6 months apart, both before and after the exercise regimen. This was all completed back in 2011.

Previously, they reported that there was no difference in telomere length between the “exercise” group and the control group. So how can they publish a new study that seems to reach the opposite conclusion? It turns out there isn't a new study at all, but a re-analysis of the original data.

In the early study, the exercise program did have some significant effects: it increased the amount that people walked around by 1663 steps per day, and decreased their sitting time by 2 hours per day. However, people in both groups spent less time sitting over the course of the study. So the scientists re-analyzed the data and looked at telomere length as a function of four more measurements. For one of these measures, change in sitting time per day, telomere length was reduced enough that the relationship showed a p-value of 0.02.

Unfortunately for Sjögren, this new finding is based on just 12 individuals. That's a tiny number for a scientific study. And when I looked at the key figure in the paper, it’s pretty clear that the effect depends critically on just 2 of those 12 individuals who had both reduced sitting time and longer telomeres. Take those 2 people out, and the effect vanishes. The authors admitted that
“The study sample is small and we cannot rule out that the findings are a chance phenomenon.”
We've seen this sort of thing before: a small study with a minimally significant effect. Usually these types of results never get replicated. As much as I’d love to believe I could lengthen my telomeres by standing up a bit more each day, this rather implausible findnig is simply unconvincing. It’s based on a sub-group of only 12 people—and furthermore, this is a re-analysis of previous data, which feels an awful lot like cherry-picking. If there is any effect, it’s very small.

Nevertheless, other studies do show health benefits from spending more time walking and less time sitting. A daily walk probably confers the same benefit as a standing desk, but a standing desk isn’t a terrible idea either. Just don’t count on it to lengthen your telomeres.

Should we test all women for breast cancer-causing mutations?

In this week’s Journal of the American Medical Association, famed geneticist Mary-Claire King argues that all women over age 30 should be tested for cancer-causing mutations in the BRCA1 and BRCA2 genes. King, who made the original discovery of the link between BRCA1 and breast cancer, is one of the world’s leading experts on how mutations in these genes cause cancer.

But her proposed new universal testing policy, which fellow Forbes contributor David Shaywitz calls “audacious,” goes far beyond what other experts recommend. Earlier this year, the highly regarded U.S. Preventative Services Task Force (USPSTF) recommended testing BRCA genes only in women with a family history of breast or ovarian cancer. 

Although there’s no question that King is an expert on BRCA gene testing, I think she’s gone much too far with her latest proposal. She has the science right, but she is far too optimistic about how her recommendation would actually play out. The policy might save some lives, but it would also cause a great deal of pain.

First, it’s worth explaining why King thinks universal BRCA testing is a good idea. In her JAMA article, King and colleagues describe a new study they conducted in Ashkenazy Jews that showed, somewhat surprisingly, that 
“50% of families found to harbor BRCA1 or BRCA2 mutations had no history of breast or ovarian cancer that would have triggered clinical attention." 
In other words, under current policy guidelines, 50% of people who have a damaging mutation in one of these genes will not have their genes tested. Many of them will eventually get breast or ovarian cancer—as King explains, women with harmful BRCA1 mutations have a 60% risk of cancer by age 60, and for BRCA2 the risk is 33% by age 60. That’s a very high risk, though it’s important to keep in mind that many women with these mutations will never get cancer.

With modern DNA sequencing technology, any large-scale genetic BRCA testing program is likely to uncover thousands of mutations that have no harmful effects, and thousands more whose effects are simply unknown. (Aside: each BRCA gene spans about 80-90 thousand nucleotides of DNA, and each of those letters can mutate in 4 ways, changing into one of the other 3 bases or just being deleted. This means there are at least 400,000 mutations possible in each gene, not counting larger deletions. A colleague and I published an article in 2010 describing one such BRCA test.) King is clearly aware that such reporting these mutations to patients would only sow confusion, and she recommends that:
“Testing for BRCA1 and BRCA2 should focus solely on unambiguously loss-of-function mutations with definitive effect on cancer risk…. A VUS [variant of unknown significance] can increase confusion and compromise clinical management; for population-based screening, these variants should not be reported.”
Herein lies one of the biggest problems with King’s idea. We don’t have universal agreement on which mutations have no significance, and even if we did, most physicians are not experts on cancer genetics. In our lawsuit-prone medical culture, there exists an unfortunate tendency to over-treat and over-report everything. 

Thus I fear that if we had wider BRCA testing, clinical labs would report all mutations back to physicians (how could they not?), and physicians in turn would report everything to the patients. The result would be that millions of women would be told "you have a mutation in BRCA1, and we don't know what it means." What's a patient supposed to do with that?

The other problem is that the only treatment to prevent breast and ovarian cancer is surgery to remove a woman’s breasts and ovaries. We don’t have a pill you can take, or lifestyle changes you can adopt, that will dramatically reduce your risk of hereditary cancer. But unlike a cancer diagnosis, the discovery of a BRCA mutation does not mean you have cancer. It simply means you have a risk, possibly a high risk, of getting cancer at a young age. We know from decades of research that people are not very good at evaluating risk. We tend to over-estimate the danger of events that seem very dramatic or visible to us, as cancer is to many people. 

By King’s own estimates, widespread BRCA testing would detect cancer-causing mutations in 250,000 to 415,000 women in the U.S. This estimate assumes the test doesn’t have false positives, which it almost certainly would. All of these women would then be faced with an extremely difficult dilemma: should they have both their breasts removed, or live the rest of their lives in fear of breast cancer? 

This dilemma was famously on display last year, when actress Angelina Jolie revealed in a New York Times article that she’d had a double mastectomy, after discovering that she carried high-risk BRCA mutations. Jolie’s mother died from cancer at the age of 56, and she explained in her article that as a result of the surgery, “ I can tell my children that they don’t need to fear they will lose me to breast cancer.”


King’s proposal is audacious, and it’s well worth debating. But without a better treatment option, telling hundreds of thousands of women that they have a high risk of breast and ovarian cancer carries a potentially enormous cost, both physical and emotional, for these women. Rather than putting huge numbers of women under the surgeon’s knife, we should instead double or triple our investments in research on treatments that may eventually make surgery unnecessary. 

Do high voltage power lines cause cancer?

This could be a very short article. I could just write “no, power lines don’t cause cancer"—but that wouldn't explain why so many people believe otherwise. And it won’t help people who are thinking about buying a home that has power lines nearby. So let’s look at this question a bit more closely.

For the past century or more, humans have been surrounding ourselves with an ever-growing array of electrical devices. All of these devices create electrical or magnetic fields, often called EMFs. There’s no doubt that our exposure to EMFs has increased dramatically in modern times. Not surprisingly, many people have worried that this is a bad thing. The belief is so pervasive that NIH has at least two websites devoted to this topic, one by NIEHS and one by NCI, as does the Medical College of Wisconsin. Realtors have created webpages to inform home buyers about how power lines might affect the value of their home. Not surprisingly, you can easily find companies on the Internet that will sell you devices (such as SafeSpace and EMFshield) to protect your body from the supposed perils of EMF.

People worry especially about high-voltage power lines, probably because they are carried by very large, highly visible structures that look vaguely threatening. This fear seems to have started with a 1979 study in which Nancy Wertheimer and Ed Leeper reported a correlation between high-voltage power lines and childhood leukemia in the area around Denver, Colorado. Wertheimer's results spurred numerous studies in the years since. A review of the evidence in 1995 pointed out that
“There is no known mechanism by which magnetic fields of the type generated by high voltage power lines can play a role in cancer development. Nevertheless, epidemiologic research has rather consistently found associations between residential magnetic field exposure and cancer.”
Scientifically, the question at the time was, were these associations real or coincidental?  If they were real, what’s the mechanism? Clearly, further studies were needed. Well, twenty years later, the data are in: power lines do not cause cancer.

In 2002, the WHO commissioned a huge (339 pages) and very thorough report on all the types of electrical and magnetic fields on the planet and how these EMFs might effect our health. Among its findings were:
“There is little experimental or theoretical evidence that mutations could be directly caused by ELF [extremely low frequency] magnetic fields…. There is little evidence that ELF electric or magnetic fields can cause malignant transformation of cells in culture.”
The final conclusion of the WHO commission was that
“Static electric and magnetic fields and extremely low-frequency electric fields are not classifiable as to their carcinogenicity to humans (Group 3).”
Group 3 means we don’t have any positive evidence that EMFs cause cancer. The only lower category, Group 4, would mean we have evidence that electromagnetic fields do NOT cause cancer, but such evidence is very difficult to produce. In other words, they concluded that the evidence didn't support a link, but more studies might yet find something.

After the 2002 report by the WHO, a study in 2005 raised the alarm again. In that study, Gerald Draper and colleagues claimed to find an association between the distance to the nearest high voltage power line and childhood leukemia. Draper found that living less than 200 meters from these power lines (in England and Wales) raised the risk of leukemia significantly compared to living at least 600 meters away.

The scientific reaction to the Draper study immediate and highly critical. Hepworth and colleagues pointed out that the results did not support a causal role for electromagnetic fields (which were not measured), but at best a geographic correlation. Kheifets and colleagues demonstrated out that the effect disappeared when the control groups were analyzed differently. Other critiques quickly emerged as well: a sign that science was working to self-correct, as it often does. But Draper’s study was widely reported, while the criticisms were not. The critiques, though, paint a compelling picture that Draper’s work was seriously flawed.

One of the most recent studies is from 2013 by Elliott et al. who looked at over 50,000 cases of cancer, including leukemia, brain cancer, breast cancer, skin cancer, and others. They found no increased risk for any of these cancer types and concluded
“Our results do not support an epidemiologic association of adult cancers with residential magnetic fields in proximity to high-voltage overhead power lines.”
This debate sounds very familiar. Many false hypotheses, such as the notion that vaccines cause autism, or that acupuncture can reduce pain, show the same pattern: a few small studies produce weak positive evidence, but then larger, better studies fail to back them up. Proponents always call for more studies, but if the effect is real, it doesn't disappear when you do a bigger study. If anything, the effect should appear stronger.

A major problem that the EMF alarmists have, which none of the proponents have ever answered, is one of mechanism: how is the very weak EMF from a power line supposed to cause cancer? Multiple theories have been suggested: maybe EMFs affect the movement of magnetic particles within cells, or alter the voltages across cell membranes—but as the editor of BMJ, Geoff Watts, put it in his response to the 2005 Draper study:
“Evidence to support these and other ideas is at best thin and at worst non-existent.”
So no, electrical power lines do not cause cancer. But they're still ugly. We should bury them all underground.