Are Power Lines and Other Electromagnetic Fields Dangerous?

Dear Dr. Zoomie – I keep hearing about how dangerous electromagnetic fields are. Should I be worried about the power lines near my house? And the wiring in my house? And my electric razor? And all that other stuff? I don’t want to be Amish – but I don’t want to get sick either!

The first time I came across this question was over 20 years ago – and it was about a decade old even then. In my case, my father was trying to sell a house that was close to some high-voltage power lines and he couldn’t understand why people didn’t want to buy it. Someone finally told him that they were worried about electromagnetic fields around the power lines. My dad asked me what I could tell him about the science behind these worries. The short version is that these fears were unfounded and the risks from power lines – and electromagnetic fields in general – is vastly overstated. Here’s the longer version of the story.

Are Power Lines Dangerous?

Are Power Lines Dangerous?

This whole story starts in the late 1970s with the publication of a paper suggesting that overhead power lines (and the electromagnetic fields they produce) were associated with cases of childhood leukemia. Although nobody was ever able to show how these fields could cause this disease, some scientific studies received a lot of publicity. There were dramatic videos of people holding up fluorescent light bulbs near high-voltage power lines – the electromagnetic field was enough to cause the bulbs to light up. Ever since these first studies came out people have been worried about electromagnetic fields and their possible health effects.

The problem is that the initial studies have all been discredited and subsequent studies have very clearly shown that electromagnetic fields aren’t dangerous – at least, not at the levels we find near power lines or in our homes. There’s a great summary article online (written by physics professor John Farley) about this on the Quackwatch website, summarizing the history of this debate – it also features prominently in a great book called Voodoo Science by physicist Robert Park. And there have been any number of reports in the intervening years – including some by the National Research Council – that have shown this to be a non-issue. Part of the problem, though, is that one side shows photos of kids dying of cancer while the other side shows calculations and academic studies – the emotional impact of the one side far outweighs the scientific impact of the other. But first, let’s look a little at the science.

First, you’ve got to understand that the Earth has its own electromagnetic field and every creature that has ever live on Earth – including humans – has been exposed to these fields from birth. As with radiation, we have to remember that any exposure to man-made fields is in addition to our exposure to natural fields – if the magnitude of the man-made fields is small compared to the natural ones then we have to consider that the man-made fields might not be that dangerous.

Earth's Magnetic Field

Earth’s Magnetic Field – The Earth’s magnetic field varies from about 300-500 milliGauss (unit of measurement of magnetic field strength) while the magnetic fields from power lines are only a few milliGauss.

According to both Park and Farley, the strength of the electromagnetic fields produced by power lines is very small compared to natural fields. For example, the human body is electrically conductive – we’re pretty much filled with salt water and salt water conducts electricity quite well (pure water, by comparison, is a lousy conductor). If you move any conductor through a magnetic field you’ll induce an electrical current – as we walk (or drive or fly) through the Earth’s magnetic field we induce electrical currents in our own bodies. The fact is that the electrical and magnetic fields induced by high-voltage power lines are much smaller in magnitude than are the natural fields we’re exposed to on a regular basis. To put some numbers on it – the Earth’s magnetic field varies from about 300-500 milliGauss (unit of measurement of magnetic field strength) while the magnetic fields from power lines are only a few milliGauss. If small variations in magnetic field strength can cause health effects then we’d expect to see much greater health effects among people moving from place to place on Earth. The fact that we don’t see these changes (for example, cancer rates are about the same in the North and in mountainous states as they are in the South and in low-lying states) suggests that the much smaller variability from power lines won’t be harmful.

Something else to consider is what I touched on earlier – there is no plausible mechanism for how external magnetic fields can cause cells to become cancerous. Think, for example, if someone gave you a can of gas and told you it could get you home. Without a vehicle of some sort the gas isn’t going to get you anywhere – you need a car to turn gasoline into mileage. At present we can’t find any way to turn external electrical or magnetic fields into genetic damage – we’ve seen nothing in human experience or in animal studies, including those of mice exposed to as much as 10,000 milliGauss.

It also turns out that the original study had some problems, the biggest one being that the authors of the study never actually measured magnetic field strength. Once follow-up studies were done that did make this rather important measurement it turned out that there was no correlation at all. Not only that, but the initial studies looked at only relatively small numbers of people. When larger studies were performed, including measuring magnetic fields, the apparent correlations melted away.

On top of all this, we’ve got to look at what’s possibly the most important piece of information – age-adjusted cancer incidence rates have been dropping steadily for several decades in spite of the fact that our exposure to electromagnetic fields has increased astronomically in those same decades. Think about it – we live our entire lives surrounded by electromagnetic fields – the wiring in our homes, overhead power lines, our computers and monitors, electric razors, televisions and entertainment systems, microwave ovens, and so forth and so on. Seventy years ago, many Americans didn’t even have electricity in their home, and those who did used it primarily for lighting – today, we use it for everything.

All this being said, are there things about the health effects of electromagnetic fields that we don’t know? Of course. We don’t – we can’t – know everything. And, let me add, the fact that we don’t know everything is often used as rationale for continuing to be frightened while further studies are being performed. The question, though, shouldn’t be “Do we know everything?” so much as “Do we know enough?” All of the evidence to date tells us that we know enough to conclude that these levels of electromagnetic fields are not causing harm. There is an awful lot of scientific evidence and scientific reasoning that tells us that electromagnetic fields aren’t nearly the hazard they’re portrayed to be.

At the same time, we know that we get a lot of benefits from the use of electricity – if we’re going to look at the potential downside then we also have to look at the benefits and the billions of lives that have been made better by its use. Let’s think about it for a moment – even if there’s a small risk from using electricity, it makes possible things like street lights, x-ray machines, computer control systems, aluminum and steel manufacture, air conditioners, elevators, and so much more. Electrical power makes our lives better, longer, and healthier – stopping (or even scaling back) its use would certainly add risk to all of our lives. We know that driving puts us all at risk – in the US, almost 1% of us will die in a traffic accident – but we accept this risk because of the benefits we derive from cars and trucks. Similarly, even if (against all scientific evidence) electromagnetic fields turns out to carry with them a small risk, I would argue that we derive far more benefit than risk from their use – if our goal is to make our society as safe as it can be then we should continue our use of electricity.

Finally, for what it’s worth…I have read up on this topic, if only to find out if my father (and those who eventually bought his house) faced any risk. While I’m neither a physicist nor a physician, I understand the science well enough to follow the scientific papers I’ve read and they make sense to me. After taking a look at the science and the epidemiological evidence and after reading the conclusions of scientists I respect (Park and Farley) I’ve decided that this is something I’m not going to be worried about. So I use my electric razor, my computers, my microwave, and all of the other electrical and electronic stuff in my apartment. I guess you’ve got to decide for yourself what you feel comfortable with, but I’d suggest that your concerns about electromagnetic fields might be misplaced.

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