Well this is the thing, electric fields are not a single thing. As others have said, a static field is by definition practically undedectable, it is the frequency of its oscillation that determines the effect. A power line is operating at 60 cycles - doesn’t do anything much, the Earth itself having some 7 cycles per second variability also doesnt do much, but then a microwave oven is tuned to interact with water molecules and generates heat - microwaves will cook you but wont heat something that doesn’t contain water (or molecules of a similar size). Keep going up in frequency and you can get to the point where it heats oxygen (43GHz or something like that I cant recall). There will be frequencies for brain tissue etc, but higher frequencies are also very short range so distances have to be small from the emitter or the power level extreme etc etc.. it's not a monolithic thing, but a spectrum. Some of it is light, some Xrays, etc etc.
A static field is always detectable. We use Earth's magnetic field for compass orientation. We have the ability to measure both magnetic and electric fields, both of which can be static in nature. It is fairly well established that migrating birds are able to orient themselves to the terrestrial magnetic field.
That aside, interaction with molecules depends on the molecule's electromagnetic resonance, as you say. There are other effects that depend on field strength. Put a metal implement or pot in a microwave and watch the sparks fly. What can always happen is for a high amplitude wave of nearly any frequency to have a strong enough transient electric field that it can ionize the air it is passing through. But any heating only persists up to a point where the molecule is at a new equilibrium temperature. After that, there is no more net absorption, because the molecule is emitting as much as it absorbs. In the case of water, this can be pretty hot. In the case of ammonia, not so much.
Human tissue is dominantly water. We are a huge heat sink for any heating due to microwaves. The issue is intensity (power/unit area). Radars operate with high intensity, and the military has developed standards for safe operation with personnel in the vicinity. Millimeter waves have been part of military technology since the 1980s, so it is not like they are an unknown quantity.
The problem I have with the scare reflex is that the papers I have seen treat the subject in obscure ways, with measurements that are not helpful to the determination of a safe environment. What I am interested in is (1) frequency, or wavelength, (2) exposure intensity, and (3) mechanism of effect and on what. Measurements of electric field potential are pretty meaningless. I can be touching an electrostatic generator and be at a very high potential, but it means nothing.
I don't hold my cell phone to my ear for reasons of caution, but because cell phones are designed for pocket convenience, not for ergonomics. In order to hear well, I orient it so I am speaking directly into the microphone and the speaker is oriented directly at me. Maybe I am doing myself a favor, but the jury is still out. (I have a vision of a nitinol mesh pad that opens up into an actual handset that fits the head, with microphone and speaker in place for mouth and ear, and then collapses back into a pad again. Dream on.)
Well this is the thing, electric fields are not a single thing. As others have said, a static field is by definition practically undedectable, it is the frequency of its oscillation that determines the effect. A power line is operating at 60 cycles - doesn’t do anything much, the Earth itself having some 7 cycles per second variability also doesnt do much, but then a microwave oven is tuned to interact with water molecules and generates heat - microwaves will cook you but wont heat something that doesn’t contain water (or molecules of a similar size). Keep going up in frequency and you can get to the point where it heats oxygen (43GHz or something like that I cant recall). There will be frequencies for brain tissue etc, but higher frequencies are also very short range so distances have to be small from the emitter or the power level extreme etc etc.. it's not a monolithic thing, but a spectrum. Some of it is light, some Xrays, etc etc.
A static field is always detectable. We use Earth's magnetic field for compass orientation. We have the ability to measure both magnetic and electric fields, both of which can be static in nature. It is fairly well established that migrating birds are able to orient themselves to the terrestrial magnetic field.
That aside, interaction with molecules depends on the molecule's electromagnetic resonance, as you say. There are other effects that depend on field strength. Put a metal implement or pot in a microwave and watch the sparks fly. What can always happen is for a high amplitude wave of nearly any frequency to have a strong enough transient electric field that it can ionize the air it is passing through. But any heating only persists up to a point where the molecule is at a new equilibrium temperature. After that, there is no more net absorption, because the molecule is emitting as much as it absorbs. In the case of water, this can be pretty hot. In the case of ammonia, not so much.
Human tissue is dominantly water. We are a huge heat sink for any heating due to microwaves. The issue is intensity (power/unit area). Radars operate with high intensity, and the military has developed standards for safe operation with personnel in the vicinity. Millimeter waves have been part of military technology since the 1980s, so it is not like they are an unknown quantity.
The problem I have with the scare reflex is that the papers I have seen treat the subject in obscure ways, with measurements that are not helpful to the determination of a safe environment. What I am interested in is (1) frequency, or wavelength, (2) exposure intensity, and (3) mechanism of effect and on what. Measurements of electric field potential are pretty meaningless. I can be touching an electrostatic generator and be at a very high potential, but it means nothing.
I don't hold my cell phone to my ear for reasons of caution, but because cell phones are designed for pocket convenience, not for ergonomics. In order to hear well, I orient it so I am speaking directly into the microphone and the speaker is oriented directly at me. Maybe I am doing myself a favor, but the jury is still out. (I have a vision of a nitinol mesh pad that opens up into an actual handset that fits the head, with microphone and speaker in place for mouth and ear, and then collapses back into a pad again. Dream on.)