Monthly Archives: October 2015

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.

How to Do Radiation Surveys and Contamination Surveys

Dear Dr. Zoomie – I’m trying to figure out what goes into a radiation survey program and I have to admit I’m drawing a blank. Can you tell me how often I should be doing radiological surveys? Also, can you tell me how to do a survey? Thanks!

I should start by saying that I can often make a pretty good guess about the quality of a radiation safety program by looking at the quality of their surveys. In general, if I audit your facility and see that you’re doing your surveys properly then it’s pretty safe to say that the rest of your radiation safety program is likely to be squared away; at the same time, if you’re missing surveys or being slipshod in your survey technique I’m probably going to find other problems as well. Now, let’s talk about what goes into a survey program and how surveys are performed.

When to survey

We’ll start with when you should be surveying. First, there is no regulatory requirement on this – your survey requirements will be set by your internal procedures, your license application, and your license conditions. You’ll have to use your own judgement as to how often various areas need to be surveyed – if you don’t have the experience to make this decision on your own it’s not a bad idea to ask a consultant for suggestions, or even to ask your regulators what they recommend. Here are a few things to think about:

  • Will people be using unsealed sources of radioactivity? For example, are they working with radiopharmaceuticals or radiolabeled compounds that can cause a spill? If so, you might want to ask people to survey workbenches or fume hoods for contamination daily when the area is in use and to survey the entire room (laboratory, hot lab, etc.) monthly.
  • Are there activities taking place that can be expected to cause contamination? For example, in a rad waste storage room, are you compacting waste, crushing vials, or moving a lot of packages? If so then you should consider surveying for contamination at least weekly, as well as after any potentially contaminating activities.
  • Are you storing radioactive materials in the area? If so then you should consider surveying for radiation at least every six months, as well as after any movement of radioactivity into or out of the area.
  • Do you have radiation-generating machines (x-ray, electron microscopes, etc.)? If so, you might be required to survey annually for radiation leakage, scattered radiation, and/or the effectiveness of your shielding. If the device will be used for medical diagnosis or treatment there will be other requirements as well, including routine quality insurance checks on a daily, weekly, monthly, quarterly, or semi-annual basis.
  • Have you had maintenance on anything that could affect your radiation shielding? Have you had an earthquake, flood, or anything else that could damage your shielding? If so, you should perform a radiation survey as soon as conditions stabilize to make sure the shielding is still intact and doing its job.

These are some of the most common circumstances and your facility might not fit into any of these categories. The important things are to think about how frequently people are using radiation and radioactivity, how potentially dangerous it can be, and what can happen that could cause radiation or contamination to be higher than what you’d normally expect (or want) them to be.

The next part of this discusses (briefly) how to perform radiation and contamination surveys. But please not – this is not the same as receiving formal training – this is a guide, but you should really receive appropriate training and develop a formal survey procedure before you do your own surveys. And remember – before you start ANY survey, make sure your instrument is in calibration, check to make sure the batteries are OK, ensure the meter, probe, and cable are all in good condition, and (for count-rate instruments) make sure to response check against a source of known strength.

Performing radiation surveys

Performing radiation surveys isn’t too difficult – mostly you’ll be walking around with your radiation dose-rate meter watching the dial; make a note of the dose rate on your survey map anyplace from time to time, especially in places where dose rates are higher than the rest of the area being surveyed. As a default, hold your meter about waist-high unless you’re measuring a specific location (say, in front of a source storage safe or a low-temperature freezer). Finally, you’re most interested in dose rates in “accessible areas” – that’s about one foot (30 cm) from any surface, and only in areas where a person could actually be expected to enter. So you don’t need to survey inside of refrigerators or fume hoods unless you expect people to spend a lot of time inside of them. Oh – and make sure that your meter has been calibrated within the last year so that your survey counts! All of your meters have to be calibrated annually (according to regulations) and you can’t meet a legal requirement with an illegal meter.

Chuck Surre, a University of Rochester radiation safety technician is shown here performing a radiation survey around some drums of just-compacted radioactive waste in the waste storage room.

Chuck Surre, a University of Rochester radiation safety technician is shown here performing a radiation survey around some drums of just-compacted radioactive waste in the waste storage room.

Performing contamination surveys

The key to any contamination survey is “low and slow.” You want to keep the detector as close as possible to whatever it is that you’re surveying without being so close that you contaminate the detector. And you want to move the detector no more than about 2-3 inches (about 5-8 cm) per second. If you hold the detector too far away you can miss some contaminated areas, and if you’re surveying too quickly then the probe might not be over a contaminated area long enough to pick up any counts. You should also try to survey as much of the surface as possible – 100% of the surface if you can – to avoid missing any contamination.

Alternately, you might want to perform a smear wipe survey to look for removable contamination (contamination that could come off on your hands or feet) – especially if you’re looking for radionuclides (such as tritium or carbon-14) that aren’t easily detected by hand-held radiation detectors. For a smear wipe survey you’ll need to use a piece of dry filter paper (a Watman or Milipore filter will do the trick) and you’ll need to wipe an area of 100 square centimeters (about 4”x4”). Apply enough pressure to the wipe to pick up any loose contamination, but not so much that you tear the wipe.

After you’re done with your survey you’ll have to records your results on a survey map; your survey map will have to be filed and maintained for three years (under normal circumstances) or longer if your survey is used to reconstruct the radiation dose to one of your workers. And – again – remember that there’s more to doing surveys than what’s provided here; this will give you a start, but there’s a lot more to the topic than what’s written here.

Sample Forms

  1. radiation_and_contamination_survey_procedure (PDF)
  2. radiation_and_contamination_survey_procedure (DOC)
  3. sample_radiological_survey_report_form (DOC)
  4. sample_radiological_survey_report_form (PDF)

Smugglers Selling Radioactive Materials to ISIS – What If They Succeed

Dear Dr. Zoomie – I just read in the news today that they caught criminals trying to sell radioactive and nuclear materials to ISIS in Moldova. What gives? I thought it took a nation to make a nuclear weapon – I’m assuming I should be scared; how scared should I be? Do I need to update my life insurance?

The threat of radiological and nuclear terrorism has been a concern for a number of years and this article is only the latest of a number of articles on this threat. There’s a lot in here so let’s take things one at a time, starting with the easiest.

The article mentions the isotope Cs-135 (cesium-135) as possibly being available for purchase by terrorist organizations to use to make a radiological dispersal device (the so-called “dirty bomb”).  There’s been a lot written about dirty bombs and I won’t add to that here except to note that ISIS has mentioned their pursuit (or possession) of radioactive materials to use in making such a device. This particular isotope (Cs-135) is an odd one to mention – it’s neither as widely used nor as dangerous as Cs-137 – it’s produced in nuclear reactors but is usually disposed of as radioactive waste. It also has a fairly long half-life (so it’s not intensely radioactive) and it emits beta radiation, which is not terribly dangerous. So this nuclide could be used as a nuisance, but it poses much less health risk than Cs-137. The fact that this nuclide is being offered suggests that either the person doesn’t know exactly which nuclide they have, that they’re making something up, or that they have access to spent (or reprocessed) reactor fuel or nuclides that can be scavenged from it.


Members from the Oregon National Guard’s 102nd Civil Support Team approach a mock crash scene, ready to take readings and assess levels of contamination by a “dirty bomb” at a joint-agency exercise held Feb 15, 2006 at the Portland Fire Department’s training facility in north Portland.

The article also mentions plutonium. There is a fissionable isotope of plutonium that’s used in nuclear weapons (Pu-239) but this is produced in nuclear reactors and then must be chemically separated from the spent fuel using some fairly complex chemistry. Pu-239 is too valuable as a fissionable material to be used in a dirty bomb, and it’s a lot harder to fashion into a nuclear weapon than is uranium – chances are that, if plutonium is being sold as a potential RDD material, it’s more likely to be Pu-238. Pu-238 is fairly common – although it’s not fissionable (so it can’t be used to make nuclear weapon) it is fairly highly radioactive. Its primary use is in spacecraft in the form of radioisotopic thermal generators (RTGs) due to the high levels of heat emitted by the decay of Pu-238 atoms. It’s also toxic, although (contrary to common misconception) it’s not the most toxic substance known to science. In any event, an RDD made with Pu-238 would be a great way to make a mess, but it’s not likely to put many (if any) people at risk since the radiation it gives off (alpha radiation) is fairly innocuous unless it’s inhaled or ingested. It would, however, make a huge mess – it could contaminate a large area, cause a huge financial impact, and would likely cause a degree of panic – but the perceived health risk would very likely far outstrip the actual danger.

Finally we get to the weapons-grade uranium that was mentioned.  The nuclear weapon that was dropped on Hiroshima contained a little over 60 kg of highly enriched uranium; this story mentions that the seller had 100 grams of weapons grade uranium with him and promised to deliver it in 1-kg batches at a cost of about $32 million per batch.  To make a Little Boy-type device would require over 60 transactions and a total cost of two billion dollars. The financial part of it is beyond the reach of most (but not all) of our enemies – this narrows the list of potential buyers. Equally important is the sheer number of transactions that would need to take place for a terrorist group (or rogue nation) to get their hands on a bomb’s—worth of material. Sixty transactions greatly increases the odds of being caught by law enforcement or intelligence agencies and having the whole plot unwind. This isn’t to say that this would be impossible – but the more complex a plan is, the less likely it is that it will be successful. It’s certainly possible that a criminal organization might have access to large quantities of weapons-grade uranium, but it’s also possible (perhaps more likely) that the seller has just enough of the material to get rich and that the supply would dry up after just a handful of sales. So, while we have to take this report seriously, I’m not sure that it’s time to start buying nuclear bomb insurance.

Taking all of this together, what have we got?

Well, first we now that there’s a continuing interest in putting radiological or nuclear materials into the hands of groups that wish us ill. And if organized crime organizations really have found sources of radiological or nuclear materials – and if they have found buyers – the possibility of an attack of some sort is quite possibly higher today than in the past. On the other hand, there have been attempts at radiological and nuclear smuggling for at least a decade – what makes this report different is the apparent involvement of organized crime.  The biggest unknown is whether this group has access to enough uranium to make a weapon and whether or not a terrorist group has access to enough money to buy it all.  Right now we just don’t know the answers to these questions.