Rear-seat EMF below 2mG to reduce risk of childhood leukemia?

Rear-seat EMF below 2mG to reduce risk of childhood leukemia?

Hello all,

As many of you know, EMF is generally considered safe, even at high exposures. Nevertheless, studies have found a link between high power lines (which emit EMF) and childhood leukemia [1], and possibly some forms of brain cancer. While statistically significant, the risk is modest, and there is no known mechanism of action. Attempts to reproduce the findings in animal models have failed.

While there is no proven causative link (and, in fact, this leukemia could be explained by other factors, such as high pesticide use around high power lines), prudence dictates that I limit my children's exposure to EMF to a level below 2 mG. That would include the rear seats of a Tesla, in which my children might be sitting for hours a day in car seats, unable to shift their position, for years.

Has anyone measured AC magnetic fields in the rear seat of a Tesla with a tri-axis gaussmeter? What were the readings at cruise and under hard acceleration? Has anyone attempted to redirect the fields using a nickel-iron based alloy like mu-metal?



P.S. The following responses are not helpful:
a) Mockery.
b) Statements that EMF is non-ionizing (noted, but ionizing radiation is not the only cancer promoting agent).
c) Links to research on EMF in animal models (noted).
d) Statements that much higher exposures to EMF exist elsewhere in a household (yes, but not for hours at a time, every day of the week for years, and not to infants).
e) Links to other threads, unless the linked-to thread answers my question specifically.

olanmills | February 25, 2013

If there is no evidence there's a problem, then why would "prudence [dictate] that I limit my children's exposure to EMF to a level below 2 mG"?

Timo | February 25, 2013

Lets change this another way of thinking: we know that gasoline fumes and exhaust gases are unhealthy without any doubt.

So you are changing one known health risk to something so small that it haven't even been proven exist. I wouldn't worry about that.

Pungoteague_Dave | February 25, 2013

These are batteries. There is no EMF. I cannot believe that people waste their time (and ours) on this type of thing and then attempt to innoculate their posts by listing the sort of responses that are "not helpful." But I will run outside right now with my tri-axis gaussmeter and slide a sheet of mu-metal over the seat to see if there is any difference...

New flash: Your kids WILL be dead within 100 years. My kid flies a jet real close to outer space and experiences all kinds of strange emissions, with weapons hanging underneath, protecting our airspace and your right to stew and worry. Guess how much sleep we are losing tonight? Your poor kids - redefines helicopter parent. I bet there's no chocolate or Santa Claus in their future either.

KayaSoze | February 25, 2013

Actually, there is a lot of evidence that EMF exposure has an effect on childhood leukemia rates. If I may quote the National Institutes of Health, from the link above:

"However, epidemiological studies (studies of disease incidence in human populations) had
shown a fairly consistent pattern that associated potential EMF exposure with a small increased risk for leukemia in children and chronic lymphocytic leukemia in adults. Since 1999, several other assessments have been completed that support an association between childhood leukemia and exposure to power-frequency EMF."

The only question is whether or not the link is causal, or whether alternative explanations can be found. Some studies to attempt to account for confounding factors, such a socioeconomic status, but to date no alternative explanation has been offered for the association. I repeat--failure to reproduce this association in laboratory animals is a valid counterargument to a causative link.

Dave, I recently tested a Ford Focus Electric with a tri-axis gaussmeter, and found back-seat EMF levels to be above those of a non-electric car, even though the battery is DC. Perhaps this is because the car uses an AC electric motor. So I can assure you that DC electric cars can produce AC magnetic fields above those of conventional cars, at least when measured from the back seat. Interestingly, I have found hybrids to produce even more EMF in the back seat than fully electric cars.

Timo, I appreciate the additional perspective on the tradeoffs of EMF exposure vs. gasoline vapor exposure. Indeed, studies have shown that gas station attendants have higher risks for some types of cancers. Driving on, or living next to a highway is certainly not healthy. It is a tough call to say that it is more dangerous to my children for me to tank up at an outdoor gas station than it is for me to expose them to a possibly high level of EMF for hours at a time, every day. And, of course, overshadowing all of these concerns the fact that automobile accidents are themselves most dangerous aspect of driving, by far, and the best thing one can do from a purely selfish perspective is to drive the largest car possible. However, I also value sustainability and good citizenship, and am willing to consider a smaller electric car for the good of humankind in general. Everything in life is a calculated risk, with good and bad aspects, and I'm simply asking for information to help me make that calculation.

Tiebreaker | February 25, 2013

@Kaiser - what were your measurements?

Earth's magnetic field is 0.25-0.65 G (250-650 mG). From the article you quote:

"The earth’s magnetic field of about 500 mG is thought
to be produced by electric currents flowing deep within the earth’s core."

Tiebreaker | February 25, 2013

Oops, sent too soon....

I would guess that to "limit your children's exposure to EMF to a level below 2 mG", you will have to move them to another planet. However, there they will be exposed to cosmic radiation, a much more dangerous prospect.

jk2014 | February 25, 2013

Elon's working on that problem right now... Cosmic radiation exposure on children in the dragon vessel traveling to mars. (Elon 9/13/06)

jk2014 | February 25, 2013

Not really, just wanted to be an a-hole and post

penguin_brian | February 25, 2013

To put it another way: Just because there is no evidence that it is dangerous, doesn't mean it is safe. History is full of things that we once deemed safe, but now consider very dangerous. e.g. lead and asbestos immediately come to mind.

Once upon a time they very likely considered car exhaust fumes to be completely safe...

@Kaiser "... found back-seat EMF levels to be above those of a non-electric car ..." What conditions? Was the car stationary or moving? What speed and power was used? What numbers? 100% more or 0.01% more?

danielccc | February 25, 2013

P Dave, the batteries are DC, but the motor and inverter are AC, at high power.

It's a fair question. Absense of evidence is not evidence of absense. Some people like to follow the precautionary principle whenever possible.

That said, I don't think a fixed level, like 2 mg, is an approprate goal. The goal should be simply that the car does not expose you and your children to materially more EMF than the otherwise would be. Since EMF around a point source is easy to shield, this is not an unreasonable requirement.

In fact, I would not be surprised if Tesla has already thought of this and has it under control. So most likely the only problem here is disclosure through tech specs.

KayaSoze | February 25, 2013

@Tiebreaker The Earth's magnetic field is DC, which is a static field. Most EMF concerns revolve around AC fields, as emitted by power lines and AC motors. While the earth's magnetic field is not strictly constant, you would have to be moving around the speed of light to turn it into a 60Hz AC field.

@penguin_brian I've tested four cars--it's fairly simple to bring a gaussmeter along on test drives. The Ford Focus Electric had a level of around 4 mG at car seat height, and it wasn't affected much by the car's activities. I believe the FFE has multiple batteries so many of the wires could be located father from the seats. The Ford C-Max Energi (a hybrid) had a 20 mG field relatively constant at the rear seats themselves (stronger on the driver's side), which degraded to around 10-12 mG field at approximately car seat height. Interestingly, this field was noted as soon as the car turned on and was relatively immune to acceleration and breaking. A conventional Honda Civic (ICE) has a level of around 0.5 mG except during extremely hard acceleration, when it transiently jumps to around 2-3. A late model Prius measures a fairly constant 4-6. I will say that, while readings in each car generally hovered in a fixed range, there was relatively little correlation between the activity of the car and the gaussmeter readings, with the possible exception of hard acceleration.

olanmills | February 25, 2013

I suppose if you say that correlation is evidence, then there is some evidence, though I do not consider that evidence.

There is also correlation that the way we live today, the things we're exposed to, maybe has increased the amount of different kinds of cancers people have than in the past, though there is much direct evidence that most of the advanced things we have today improve people's health and quality of life and that people in general are living healthier and longer and that also, we have better technology and medical knowledge to diagnose problems that weren't as well understood before. Some people also try to avoid all kinds of things we have today that didn't exist naturally before, even though there is more direct evidence that even if it they hypothetically did cause some problems, that they are overall a much greater benefit than they are a harm. Things like flouride, vaccinations, even things like pesticides, preservatives, and genetically modified food have improved life compared to what people dealt with before.

If there was a huge health risk, being that people have been exposed to EMF for so long now, you'd think there would be more direct evidence to be found. Instead, what people are worrying about is the lack of direct proof that it's NOT a health risk. You're never going to have that.

olanmills | February 25, 2013

"Some people like to follow the precautionary principle whenever possible."

Yeah but there's a tradeoff. If I'm on some walk in the woods, and I see some berry in the woods that might look good to eat, but I don't know what it is, well then I'm not going eat it. The potential benefit is that I will get some minor enjoyment from eating it, and the risk is that I might get poisoned and there's no one around to help me and I could die. So it's probably not worth it lol.

But then, let's say you're worried about cel phones. Well the benefit is that my life is way way better and more enjoyable and convenient with cel phones. It's also way safer. If I get lost, if I get into an accident, if there is some saftey issue or a crime in progress or whatever, I can reach out to family friends, emergency services, etc. The risk is that no scientist/doctor as proved 100% definitively that cel phones are 100% harmless in every single way imaginable and unimaginable. There is no evidence definitively linking cel phone use or the presence of cel phone towers to health problems. So let's suppose you have God -like knowledge and you know there is absolutely 0 risk with cel phone usage. Well then probably, we mere humans will never be able to prove there is zero risk, and as long as someone has a concern, they can make a claim.

No suppose there is some risk of harm that cel phones cause. Suppose this risk is 100%, as in, everyone who uses a cel phone will develop a problem. Well then it is likely we would have found direct evidence of it by now. True, perhaps not. Perhaps we have not descovered a link yet, but that's unlikely. Now suppose there's some risk, but it's not 100%. Well then, what's the tradeoff?

I would argue that the tradeoff is in using cel phones. This is basically what you are weighing:

lack of evidence that something is definitively 100% safe
benefit of using that something

danielccc | February 25, 2013

@olanmills, Cell phones have been in massive use for less than 20 years. Many cancers and health issues take about 30 (asbestos, smoking, etc.) It's early days yet.

Still, I take your point. Cost-benefit. Fine. But then I want the cell phone with the lowest reasonably achievable SAR, just in case. Hey, this one is 1.2, that one is 0.4. A 3x difference is not trivial. Perhaps a moot point if the risk is low, but hey, you just get one life to experiment with.

Call it the "pragmatic" precautionary principle. You don't turn into a Luddite, but you optimize wherever possible.

penguin_brian | February 25, 2013

There are ways to reduce the risks associated with mobile phones. Such as keep phone calls short, reduce the number of calls you make (both which are also good for your bill), using a headset/hands free system, etc.

I wouldn't know how to reduce the risk with a BEV. Except for minimize driving. Avoiding traffic congestion is probably a good idea too (helps minimize driving time). Which are probably good suggestion anyway as they reduce your chances of being an an accident, and also reduces the amount of fumes you breath in from nearby ICE cars. They isn't really helpful. I don't drive unless I have to anyway, and nobody likes traffic congestion.

Tiebreaker | February 25, 2013

Is drinking water safe? Just because there is no evidence that it is dangerous, it doesn't mean it is safe. Who knows how many cancer cases throughout history were caused by drinking water?

Timo, HELP!

Tiebreaker | February 25, 2013

@Kaiser - you did not answer: what were your measurements In Ford Focus Electric?

olanmills | February 25, 2013

Wow, I hope my rambling about cel phones was comprehensible, lol. Rereading it, I see that it's not worded very well.

Brian H | February 26, 2013

Few who appeal to the precautionary principle apply it to its application. I.e., what is the possible harm from applying the cure/prevention? Very often it is substantial and known -- but discounted (because it's not unknown and scary?)

danielccc | February 26, 2013

@Brian H, that would be a misapplication of the principle.

My bottom line is that EMF should be easy to shield around a motor/inverter assembly and thus should be, and I actually think it probably is already. Tesla does not miss much.

So the argument is really one about communication. Tesla needs to improve even with basic data, such as vehicle weight. The EMF thing is one more spot on that leopard. I'd also like to see life cycle information on materials. How much of the car can be recycled?

At this early stage, I'm not losing sleep over these things. Tesla has a full plate of work to do. But over the next few months and years I would rather they publish more and better specs throughout. In fact, I would hope that they publish more and better specs than anybody else.

penguin_brian | February 26, 2013

If somebody gives me an Australian approved Tesla Model S and a tri-axis gaussmeter I will investigate the amount of shielding Tesla provides, and determine if it is sufficient or not based on some arbitrary, subjective, and completely emotional criteria.

Everyone happy now? Good.

Seriously, we can't continue this discussion without more data. It might be that the Tesla Model S doesn't emit excessive EMFs.

There is a picture of the engine at time 23:32 in the following video (and computer generated images just before), it looks like it could be completely shielded to me.

Brian H | February 26, 2013

Stay away from can openers. Wear a cloak of chicken wire at all times. You can't be too careful.

Or, maybe ...

olanmills | February 27, 2013

Dave, Dave, Dave!

Woah, man, you tried to sneak in some facts with that last link!

We are talking about EMF here. E. M. F.

Don't you get what that means? Science! Magic! Nature! Mystery! No one explain how this stuff works. It's crazy!

Tiebreaker | February 27, 2013

"The idea was picked up by Paul Brodeur, who wrote a frightening three-part article for The New Yorker that reached a large and influential audience."

Brodeur? Broder?

olanmills | February 27, 2013

Seriously guys.

ElectroMagnetic Field.

Do you guys see how many syllables that has? It's a lot. Do you think that a simple "report" on the supposed "lack" of "evidence" that there is "no" "reason" to "think" that EMF causes cancer could be conclusive? Of course not!

I'm sorry, I can't really hold out that long. I broke Kaiser's rule. My post is not helpful, and if this thread goes on, my posts are just going to get worse and worse, Kaiser. I'm just giving you a heads up.

Brian H | February 27, 2013

So can we please have the end of these Extremely Mad Fantasies here? When predictions fail, theories die. Good riddance.

danielccc | February 27, 2013

I'm pretty disappointed by some of these comments. P. Dave was so concerned about the safety loss due to a few nuts not being tight that he contacted the NHTSA. I did not agree with his assessment, which I thought was exaggerated, at best, but I did not ridicule him. Instead I said he did the right thing.

So some physicist claims that EMF is harmless based on research on power line correlations. Well, that's all 60 Hz. A very low frequency.

But microwaves cook food at 1,000 times the power output of cell phones (within three orders of magnitude). Clearly tissue absorbs energy from EMF at microwave frequencies. So it is not totally implausible that more subtle effects occur at lower power levels combined with long exposures. In fact, there is some evidence of correlation.

Is the EMF in an EV like a power cord or like a cell phone? At what frequency does the inverter work? The AC motor? I have no idea. Why not? It's simple data. Why not publish it?

lph | February 27, 2013

Did I detect a spark of EMF in that ICE? 65Kv in those spark wires!
Really folks, this is a pointless discussion without some verifed hard evidence.
I am not going to bother read any more of this thread.

Brian H | February 28, 2013

Wow, only 3 orders of magnitude! Like the diff between 0.43K and 430K (157°C)! You can cook almost anything with that. Who's to say almost half a degree above absolute zero can't, too, a little!

Waallll, me. And any scientist, or human being possessed of a mote of common sense. The world is way too non-linear for some folks, though. Simplistic straight lines is all they can think in.

And they are not harmless. Given a chance, they will precautionarily bring almost everything to a halt, because somewhere on a straight line running through that point is DANGER! (The only thing that makes life interesting.) So it must be PREVENTED! PRECAUTIONARILY!

Bah. ♪♪If you go out in the woods, today♪♪

Brian H | February 28, 2013

News flash. Infants should get about a teaspoon of yard dirt a day. Teaches their immune systems lessons it will need, if they're not going to die quite young.

danielccc | February 28, 2013

Talk about fantasy. Name one technology that was ground down to a halt due to unjustified precaution. Just one.

And sure, the power level is three orders of magnitude less, but the cumulative exposure time is easily three orders of magnitude more. Food is cooked in minutes. People spend thousands of hours on the phone.

Brian H | February 28, 2013

People, and their bodies, are not passive recipients of such influences. They react and cope dynamically, and very effectively within wide margins. In fact, the coping itself is beneficial, since it keeps repair and metabolic systems active and flexible. Freedom from challenge is a very bad policy and goal.

olanmills | February 28, 2013

@danielccc the thing is, and I don't mean to be too insulting, but people don't know what they're talking about sometimes.

"But microwaves cook food at 1,000 times the power output of cell phones (within three orders of magnitude)."

Microwaves are electromagnetic radiation, and that is very different from EMF (electromagnetic field). Yes, it is very unsafe to stick your head in a microwave. Yes it is unsafe to stand in front of a microwave oven for long periods of time because microwave ovens to not contain all of the microwaves and radiation comes out. However, a microwave, a radio wave, an X-Ray, this is not EMF. This is EMR.

"Clearly tissue absorbs energy from EMF at microwave frequencies."

EMF does not radiate out energy like electromagnetic radiation, just like magnets do not radiate energy. They create a potential. Changes in an EMF, or motion relative to an EMF can induce energy in conductors, but the source of the energy is whatever the source of the motion or modulation is, not the EMF itself.

"Is the EMF in an EV like a power cord or like a cell phone?"

A power cord just has EMF. A cell phone has EMF and EMR. EMR is radiation energy.

danielccc | February 28, 2013

olanmills, we are not talking about static fields, which I don't think anybody thinks are even potentially harmful.

We are talking about fields generated by alternating current. A power cord radiates a 60Hz electromagnetic field, a radio signal, and so does an AC motor or any AC device. 60 Hz is a low frequency so the radiation is very low energy (and very long wavelength), but it radiates, for sure, as does any unshielded cable carrying an electric current that varies through time. Speaker cables, for example.

Brian H | February 28, 2013

Any effect such fields create is trivial, well within the ability of the body to handle. Making large efforts to prevent trivia is, by definition, a waste of time.

Vawlkus | March 1, 2013

Nice danielccc, you just contradicted yourself in the same post.

danielccc | March 1, 2013

Vawlkus, I did? How?

Brian H, I didn't realize you were an expert on this. The body tolerates low levels of ionizing radiation because life has been exposed to cosmic rays for the entire history of the planet. You seem to be extrapolating from that to any other kind of exposure.

The worst part of this conversation is that I don't even think EMF in a Tesla or any other EV is likely to be harmful. I would not even have brought up the subject on my own. I've engaged because of all the mocking comments and the poor thinking they expose, using language almost exactly like that used by tobacco lobbyists.

Tiebreaker | March 1, 2013

Just for fun:

So is it safe to ride in or walk around cars that have RADAR based adaptive cruise control?


Keyword is "non-ionizing radiation"

The Earth's EMF is the exact cause why life sustained on Earth, despite the bombarding of cosmic radiation.

The difference with the tobacco lobbyists is that they avoid science at all cost. Here science is applied at all cost.

Tiebreaker | March 1, 2013

@danielccc - I don't mean to be disrespectful at any level. There are many electrical engineers on this forum. A lengthy technical explanation would clarify the differences, however, more in-depth technical knowledge is needed to understand it.

There are also medical professionals on the board, I remember at least one of them questioned the effects of EMF pointing to inconclusive research. However, nobody questions if there are harmful effects from MRI diagnostics, where the EMF is thousands of times stronger.

shs | March 1, 2013


Not sure whether you are suggesting the MRI is dangerous or not, but if so, you may have it confused with X-ray-based CAT scans. MRI involves a strong static magnetic field and moderate (non-ionizing) RF fields and is considered much less potentially harmful than CAT scans.

Tiebreaker | March 1, 2013

@shs - Correct.

Tiebreaker | March 1, 2013

@shs - People are questioning the safety of the EMF produced by electrical motors, while MRI on purpose produces an EMF thousands of times stronger, and nobody worries. And they shouldn't.

MRI is absolutely safe. Just don't wear any iron accessories.

shs | March 1, 2013


I used to work for a company that made MRI and NMR spectrometers. Lots of good stories about people walking by magnets with various tools, etc. Or the lady with a bit of iron in her hip. Actively shielded magnets really do help with this problem however, that is unless you get real close.

olanmills | March 1, 2013

A modulating EMF caused by AC current is not electromagnetic radiation. Again, you are mixing up two different things. They are not entirely unrelated, but they are not the same thing.

DBT | March 3, 2013

The kid's going to be attached to a cell phone and data plan probably starting in late elementary school anyway, if not all his friends will be. How about about a study on how exposure to carbon monoxide, hydrocarbons, nitrogen oxides, soot and a whole bunch of other carcinogenic chemical compounds from not-exactly-pure gasoline effect us all? All of which cannot be avoided while driving on the road either due to your own car or other cars. Oh nevermind, we're used to that already. Not to mention decades of running leaded gasoline which put a few hundred million pounds (not an exaggeration) of lead out into the atmosphere coating almost everything. Danger - it's relative.

Brian H | March 3, 2013

Quit trying to sneak CO into the mix. It only occurs when air supply is restricted, like a closed garage.

DBT | March 3, 2013

@Brian H: or you're driving. Anywhere. If you can smell exhaust, then you are getting the whole cocktail including CO. We're surrounded by in on the road. People forgot how nasty it is because it is so ubiquitous. It's not going to go away until every vehicle is on some non-hydrocarbon fuel.

Brian H | March 4, 2013

Very little CO. It is "failed combustion" which should generate CO2, resulting from oxygen shortage. It is very reactive, and in the open air is not very stable, oxidizing into CO2. Wiki:
"In the atmosphere it is spatially variable, short lived,
Carbon monoxide is produced from the partial oxidation of carbon-containing compounds; it forms when there is not enough oxygen to produce carbon dioxide (CO2), such as when operating a stove or an internal combustion engine in an enclosed space.
Worldwide, the largest source of carbon monoxide is natural in origin, due to photochemical reactions in the troposphere that generate about 5 x 1012 kilograms per year."

Brian H | March 4, 2013

Wiki typo: "5 x 10^12 kilograms per year."