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.

A breakthrough cure for acute leukemia?

This week a group of scientists from Memorial Sloan-Kettering Cancer Center published what may be a genuine breakthrough in the search for a cure for cancer. The simple word "cancer" disguises what is really hundreds of diseases, most caused by genetic mutations that make a cell start replicating out of control.  The new study looks at a deadly form of leukemia, called B cell acute lymphoblastic leukemia, or B-ALL, and describes a radically new type of cancer therapy that uses genetic modification of a patient's own cells.

First a bit of background. Leukemias are cancers of the blood, which means they don't form solid tumors at all. Instead, the cancer cells circulate in the blood, going virtually everywhere in the body.  The blood has many cell types within it, including white blood cells or leukocytes, which is the origin of the word leukemia.  Lymphocytes are a type of white blood cell, and the two most common subtypes are called B cells and T cells.  B-ALL, then, is a cancer where a B lymphocyte has suddenly turned cancerous.

Scientists have developed chemotherapies to treat B-ALL, but if the first line of treatments fail and the cancer returns, the patient faces a very grim prognosis.  We really don't have any effective treatments at this point, and most patients die.

The new leukemia therapy is a technological tour de force.  The scientific team at Memorial Sloan-Kettering, led by Renier Brentjens and Michel Sadelain, genetically modified T cells from each patient so that these T-cells would target cancerous B cells.  The modified T cells use something called a "chimeric antigen receptor," or CAR, which they designed so that it would attach itself to a specific protein, called CD19, that sticks out of the surface of most cancerous B cells.  (This technique was invented by another group at Memorial Sloan-Kettering, led by Isabelle Rivière.)

What was amazing about this study is that in all five patients, their cancers virtually disappeared in just a few weeks.  As described in a The New York Times report, one of the sickest patients, 58-year-old David Aponte, saw his leukemia disappear in just eight days.  But we cannot know for certain yet if the therapy alone is a cure.  This is because the patients also had stem cell transplants within a few months after therapy, which may have helped eliminate any remaining cancer cells.  The therapy itself was temporarily very toxic, requiring close monitoring and steroid treatments to lessen the toxic side effects.  This may have been the reason that one patient died: the steroids may have hampered the therapy by destroying the genetically modified cells.

If this therapy were used as a first-line treatment of B-ALL, rather than in patients who have tried conventional therapy and relapsed, it might be even more effective (as the authors themselves suggest).  In particular, it is likely to be less toxic in patients who are at earlier stages of the disease and have fewer tumor cells in their blood.  Thus despite its promise, CAR T-cell therapy needs to be refined and tested further before we can declare it a success.

I'd like to make a final observation: this work, like almost all biomedical research in the U.S., was supported by the NIH, whose budget was just cut severely by Congress with its ill-conceived "sequester."  If we keep cutting biomedical research, we won't see many more breakthroughs like this one.  Even this dramatic result, promising though it is, needs more research to improve it and to test it on other leukemias, including chronic lymphycytic leukemia and non-Hodkins lymphoma, where it has already shown very promising results.

This leukemia treatment didn't just appear out of thin air.  It uses a technology that was invented four years ago, and that technology in turn is based on other discoveries that now make it possible to re-engineer a patient's own cells and turn them into a treatment.  Who knows where the next ten years will take us?   Now is the time to be increasing our investment in biomedical research.