I’m an electrical engineer, and I often hear people who are otherwise pretty science-oriented express concern about injuries and disease being correlated to electromagnetic field (EMF) exposure. Usually these statements are pretty vague, “studies have shown” without much about what studies have shown what. So I did some digging into a few dozen different studies, meta-studies, and well-respected summaries. Forgive me for not linking every study I looked at. A couple representative ones here and here.

My goal is to accurately represent the truth of the situation, so that people will stop being afraid of things they don’t understand. Unless, of course, they should be afraid. Either way, understanding = good. Here’s how it seems to all fit together:

  • Alternating magnetic and electrical fields cause charged particles like ions to move. Your body has lots of ions in it, so exposure to alternating EMF will impact the movements of ions in your body. This seems hard to dispute just from basic physics.
  • Several studies find that exposure to alternating magnetic fields causes oxidative stress, which can contribute to basically any chemical mechanism in your body functioning worse. Tests on rats exposed to high-intensity EMFs found that they developed functional issues that were resolved with antioxidants. So oxidative stress is a plausible mechanism for exposure to alternating EMFs to contribute to injuries and diseases on a population level to some degree. Whether that degree is at all meaningful is a different question.
  • Most studies I’ve seen are done at ELF (50/60 Hz line frequency) or 900 MHz (mostly older cell phones). I haven’t seen much about 2.4 Ghz or higher that’s been in use in every cell phone for the last decade. One would reasonably expect higher frequencies to have fewer biological impacts since they don’t penetrate tissue as deeply. Since laptops, tablets, and most cell phones only operate at DC or at 2.4 GHz and higher, they seem very unlikely to be sources of any sort of problem.
  • Alternating current generates an alternating magnetic field. The biggest exposure to alternating magnetic fields for an average person is going to be from an electric blanket, which maxes out around 30 uT (microteslas) right on the surface of the skin. (That’s pretty close to the intensity of the magnetic field of the earth that you’re exposed to all day every day, though that doesn’t oscillate, so it won’t cause ions to move in your body unless you’re on a spinning teacup ride or such.) There are studies showing some temporary and reversible medical impacts on rats from alternating magnetic fields applied to their brains, but most studies are at ~100x the intensity of an electric blanket. Unless you’re a welder or working with induction furnaces, you’ll see vastly lower levels than those tests from basically every other source in your world.
  • Alternating voltage generates an alternating electrical field. Exposure to electrical fields is generally much lower than for magnetic fields except perhaps for people who live very close to high-voltage transmission lines. Frankly, I’m having trouble quantifying the fields involved and what they would do to the ions in a human-sized hunk of meat. But there are quite a number of studies that conclude a slight (almost always well within the margin of error) increase in certain diseases for people that live near high-voltage lines. The E-field effect provides a plausible mechanism for increases of certain diseases near transmission lines, despite at least one study showing a correlation between disease and transmission lines but also no correlation between disease and magnetic field exposure in the same population.
  • There are studies indicating there might be small population-level effects from long-term high-use cell phone exposure. There are also studies on microwave exposure to rat brains showing some negative impacts. But all these studies I’ve seen were done on 900 MHz frequencies. 5G phones typically run at 2.4 GHz up to 60 GHz, though they will drop back to 900 MHz in cases where range is needed. And as previously noted, those higher frequencies don’t penetrate far.

Preliminary conclusions:

  • Living near high-voltage power lines may pose a small but just-barely-measurable legitimate health hazard due to the electric (not magnetic) fields involved. I need to do more math on the E-field exposure compared to other field exposures.
  • Extreme use of early cellular phones may have presented a legitimate low-level hazard, but this has probably been resolved by newer technologies.
  • All other alternating EMF sources do contribute to oxidative stress on the body, and oxidative stress is bad. But if one was to order the causes of oxidative stress on the body, EMFs probably aren’t very high on the list compared to, say, eating fries cooked in weeks-old toxic sludge at your local fast food restaurant. I’m not sure how one would quantify this, though.

Given all of the above, whatever health impacts from EMFs exist are probably well below the noise floor for almost everyone. Rather than altering our technology or behavior, it makes more sense to remove other sources of oxidation like junk foods, consume some antioxidants like curcumin, and go on with life. Don’t unplug your nightstand clock. Don’t dress up like a baked potato. Maaaaaybe don’t live near high-voltage lines if you have an option.