5 ms·

This is a 2019 study. Would be more interesting if anyone else had managed to replicate it. Reading the study doesn’t inspire a lot of confidence in their meth

This is a 2019 study. Would be more interesting if anyone else had managed to replicate it. Reading the study doesn’t inspire a lot of confidence in their methods. They make a lot of basic errors like listing dB figures (a relative term) when I think they mean dBmw (an absolute measurement). They tested multiple frequencies but for some reason only 2450MHz showed significant effects. 900MHz and 1800MHz showed no effects, despite 1800MHz being relatively close to 2450MHz. They also didn’t use very many rats for each group. Only n=6 per frequency, which were further divided into n=3 for some of their measurements because they couldn’t use the same rat for both tests. They also chose a lot of stress-related measures which are known to be heavily influenced by mishandling the rats (e.g. if a researcher accidentally dropped one during handling) Unless someone can replicate these results and do it with more rats, I suspect the results are likely from one or maybe two rats having abnormal baseline results and that being amplified by the ultra-small sample size. As for relevance: Unless you’re standing in close proximity to a high-gain, directional antenna emitting continuous wave tones (not intermittent modulated WiFi packets) then your WiFi exposure won’t come anywhere near what they used for these experiments. Inverse square law and omnidirectional antennas mean that very little WiFi energy even makes it to people near a WiFi router.

strstr 5y ago
Water has a strong absorption peak at 2450 MHz (it’s what kitchen microwaves use).
- google234123 5y ago
  A microwave oven is 10000 times more powerful than a typical WiFi signal and is focused on an object less than a foot away.
- wtallis 5y ago
  From what I can find, it looks like the nearest absorption peak is around 20GHz, and while it is temperature-dependent, that peak doesn't shift all the way down to 2.45GHz.
- radioactivist 5y ago
  This is not really true. While the microwave absorption of water is significant at 2.4 GHz the peak is (a) quite broad and (b) centered at 10GHz or higher (higher if the temperature is raised); see plot in [0]. So ascribing some "specialness" to this frequency due to the abundance of water in living systems isn't an explanation. [0] https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#Microwaves_and_radio_waves https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_...
  - sannee 5y ago
    To expand, apparently microwaving food right at the absorption peak sucks because of low penetrance, heating only the top layer of the food. The reason 2.4 GHz was chosen was purely as that is where the ISM band already was at the time.
    - jazzyjackson 5y ago
      i’m trying to google a better answer, it seems ISM bands were chosen when microwaves were a nascent technology, so it’s a bit chicken and egg
      - anotherhue 5y ago
        2.6 was chosen based on empirical heat penetration testing for typical target food sizes, e.g. Potatoes. GE lobbied for 2.4 instead so they could emit a noisy harmonic from a crystal based 1.2 system so the FCC agreed. Source: national archives documents I researched
        jazzyjackson 5y ago
        Cool! I came across some quoras that suggested the electronics were easy for 2.4, but didn't give further detail. Noisy harmonics does sound useful for cooking!
      - sannee 5y ago
        Yeah, I do not think I have a good source at hand, this is a fun fact from an E&M lecture we had. I also wonder if anyone actually experimented with microwaving their dinner at 10GHz or if that was just an educated guess. X-band magnetrons for radars are widely available though, so I would not be surprised if that was coming from practical experience...
- jazzyjackson 5y ago
  microwaves use it because water absorbs it + multiple wavelengths can fit inside the oven for even heating + easy to produce without fancy electronics water can get shaken up by a wide band of frequencies
  - anotherhue 5y ago
    Microwaves could have used almost any frequency that was cost effective, 2.4 was a compromise to between competing companies and empirical testing.
alksjdalkj 5y ago
This is a peer reviewed article right? So presumably at least a couple other people in the field were satisfied with their methods. Are you suggesting they were wrong to accept this article?
- puzzlingcaptcha 5y ago
  The quality of the review process correlates with the prominence of the journal. Neurochemistry International is deep in the second quartile of Cell Biology journals. Those kinds of papers need to be read with extra care.
- blendergeek 5y ago
  > This is a peer reviewed article right? So is this [0]. [0] https://juniperpublishers.com/ofoaj/OFOAJ.MS.ID.555850.php https://juniperpublishers.com/ofoaj/OFOAJ.MS.ID.555850.php "Peer reviewed" does not necessarily mean high-quality or true.
  - spindle 5y ago
    OMG - thank you! That is superb!
  - gpderetta 5y ago
    "Finally, we would like to acknowledge that this study would not have been possible had it not been for the predatory journal industry. Without it, academia and society would be a better place. "
- pajko 5y ago
  Do you remember hidroxycloroquine? Just count the referred peer reviewed studies: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534595/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534595/
- Uberphallus 5y ago
  Not who you're replying to, nor an expert in the field, but yeah. This is at most an exploratory experiment that requires replication. The fact that no rat behavior change was reported until the 3 week mark heavily suggests external factors; hardly a cumulative effect as any long exposure effect would display. Moreover an interesting paragraph: > The average rectal temperatures of rat were observed to be 33.71±0.56 (control), 35.3±0.63 (EMR-900 MHz), 35.48±0.67 (EMR-1800 MHz) and 36.96±0.55 (EMR-2450 MHz) before and 33.91±0.82 (control), 35.5±0.51 (EMR-900 MHz), 35.66±0.60 (EMR-1800 MHz) and 37±0.78 (EMR-2450 MHz). Seems to indicate the 2450 MHz rats were ill or otherwise stressed (rat body temperature hovers around 35.5, though it can increase at night), but no verification or mention is done on this whatsoever. I honestly believe many of effects described in the paper can be explained with the body temperature differential. Also worth mentioning: > The animals after being exposed to 900, 1800 and 2450 MHz EMR, the average power density was found to be 0.1227 W/m2. While the overall value of whole body average SAR was found to be approximately, 0.0227, 0.030 and 0.0616 W/kg. Again not my field but I doubt 120mW/m2 can result in 50% absorption (61.6mW) per kg of rat. That means 2 kg of rats would absorb 100% of the radiation, while obviously not covering a full square meter. Please correct me if I misunderstood something. I'm not saying that 2.4GHz radiation has no ill effects, there's tons of research on rats since the inception of the microwave, but it generally show changes at higher (and certainly more clear) SAR levels.
bjarneh 5y ago
There's more peer-reviewing on HN, than the actual peer-reviewing.
- donw 5y ago
  Peer review in and of itself is of limited value, and usually reveals cosmetic, as opposed by structural, errors. How many code reviews can be summarized by the letters "L", "G", "T", and "M"? Replication matters. The echo chamber of peer review much less so.
  - bjarneh 5y ago
    > usually reveals cosmetic, as opposed by structural, errors I agree, science has become a form of writing and the peer-review will most likely figure out if you are familiar with that form.
- coldtea 5y ago
  Most actual peer-reviewing is bogus, facile comments, by people not even bothering to read the paper (when they're not in cahoots with the author and journal).
gonzo 5y ago
> when I think they mean dBmw (an absolute measurement). I think you may mean dBm or dBmW here. 0dBm == 1mW. The SI symbol for Watt is ‘W’ not ‘w’. At 2.4GHz, free space path loss is -41dB at 1m, so even a 20dBm radio and a 20dBi directional antenna (and assuming 0dB of insertion loss), the signal strength at 1m is -1dBm, or about 0.79 mW. At 3m, the free space path loss is nearly -50dB. Now the signal from the setup above is at -10dBm, or 0.1mW. https://ecfsapi.fcc.gov/file/10417871820142/2018%2BRF%2BRadiation%2BExposure%2BLimits%20(1).pdf https://ecfsapi.fcc.gov/file/10417871820142/2018%2BRF%2BRadi...
R0b0t1 5y ago
1800MHz is not that close to 2450MHz. Behavior in air is different, for one, and the properties that dictate this, the vibrational modes of atoms and so on, are extremely selective.
- inter_netuser 5y ago
  Not just atoms, you could be hitting something specific in terms of resonance at 2.45ghz. Maybe rats skull size is perfectly resonant at that frequency, who knows.
  - hansel_der 5y ago
    2,45GHz ~= 12,2 cm wavelength resonance seems plausible
  - accountofme 5y ago
    2.4GHz resonates with water. Thus why it is also used in microwaves to heat our food!
    - anotherhue 5y ago
      An urban legend. Microwaves cause heating across a wide range of frequencies.
      - coldtea 5y ago
        Not really: Consumer ovens work around a nominal 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in) in the 2.4 GHz to 2.5 GHz ISM band
        detaro 5y ago
        "Microwaves" as in "the part of the electromagnetic spectrum we call microwaves". And as they correctly point out, that consumer ovens use a specific frequency has nothing to do with it being a resonance frequency of water, but it being a reasonable to use and legal frequency to do so. They would work on 1 GHz or 5 GHz too.
markenqualitaet 5y ago
Have they controled for coil whine and similar (inaudible to humans) artifacts? Might explain a difference in frequency "response".

strstr 5y ago

Water has a strong absorption peak at 2450 MHz (it’s what kitchen microwaves use).

google234123 5y ago
A microwave oven is 10000 times more powerful than a typical WiFi signal and is focused on an object less than a foot away.
wtallis 5y ago
From what I can find, it looks like the nearest absorption peak is around 20GHz, and while it is temperature-dependent, that peak doesn't shift all the way down to 2.45GHz.
radioactivist 5y ago
This is not really true. While the microwave absorption of water is significant at 2.4 GHz the peak is (a) quite broad and (b) centered at 10GHz or higher (higher if the temperature is raised); see plot in [0]. So ascribing some "specialness" to this frequency due to the abundance of water in living systems isn't an explanation. [0] https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#Microwaves_and_radio_waves https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_...
- sannee 5y ago
  To expand, apparently microwaving food right at the absorption peak sucks because of low penetrance, heating only the top layer of the food. The reason 2.4 GHz was chosen was purely as that is where the ISM band already was at the time.
  - jazzyjackson 5y ago
    i’m trying to google a better answer, it seems ISM bands were chosen when microwaves were a nascent technology, so it’s a bit chicken and egg
    - anotherhue 5y ago
      2.6 was chosen based on empirical heat penetration testing for typical target food sizes, e.g. Potatoes. GE lobbied for 2.4 instead so they could emit a noisy harmonic from a crystal based 1.2 system so the FCC agreed. Source: national archives documents I researched
      - jazzyjackson 5y ago
        Cool! I came across some quoras that suggested the electronics were easy for 2.4, but didn't give further detail. Noisy harmonics does sound useful for cooking!
    - sannee 5y ago
      Yeah, I do not think I have a good source at hand, this is a fun fact from an E&M lecture we had. I also wonder if anyone actually experimented with microwaving their dinner at 10GHz or if that was just an educated guess. X-band magnetrons for radars are widely available though, so I would not be surprised if that was coming from practical experience...
jazzyjackson 5y ago
microwaves use it because water absorbs it + multiple wavelengths can fit inside the oven for even heating + easy to produce without fancy electronics water can get shaken up by a wide band of frequencies
- anotherhue 5y ago
  Microwaves could have used almost any frequency that was cost effective, 2.4 was a compromise to between competing companies and empirical testing.

alksjdalkj 5y ago

This is a peer reviewed article right? So presumably at least a couple other people in the field were satisfied with their methods. Are you suggesting they were wrong to accept this article?

puzzlingcaptcha 5y ago
The quality of the review process correlates with the prominence of the journal. Neurochemistry International is deep in the second quartile of Cell Biology journals. Those kinds of papers need to be read with extra care.
blendergeek 5y ago
> This is a peer reviewed article right? So is this [0]. [0] https://juniperpublishers.com/ofoaj/OFOAJ.MS.ID.555850.php https://juniperpublishers.com/ofoaj/OFOAJ.MS.ID.555850.php "Peer reviewed" does not necessarily mean high-quality or true.
- spindle 5y ago
  OMG - thank you! That is superb!
- gpderetta 5y ago
  "Finally, we would like to acknowledge that this study would not have been possible had it not been for the predatory journal industry. Without it, academia and society would be a better place. "
pajko 5y ago
Do you remember hidroxycloroquine? Just count the referred peer reviewed studies: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534595/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534595/
Uberphallus 5y ago
Not who you're replying to, nor an expert in the field, but yeah. This is at most an exploratory experiment that requires replication. The fact that no rat behavior change was reported until the 3 week mark heavily suggests external factors; hardly a cumulative effect as any long exposure effect would display. Moreover an interesting paragraph: > The average rectal temperatures of rat were observed to be 33.71±0.56 (control), 35.3±0.63 (EMR-900 MHz), 35.48±0.67 (EMR-1800 MHz) and 36.96±0.55 (EMR-2450 MHz) before and 33.91±0.82 (control), 35.5±0.51 (EMR-900 MHz), 35.66±0.60 (EMR-1800 MHz) and 37±0.78 (EMR-2450 MHz). Seems to indicate the 2450 MHz rats were ill or otherwise stressed (rat body temperature hovers around 35.5, though it can increase at night), but no verification or mention is done on this whatsoever. I honestly believe many of effects described in the paper can be explained with the body temperature differential. Also worth mentioning: > The animals after being exposed to 900, 1800 and 2450 MHz EMR, the average power density was found to be 0.1227 W/m2. While the overall value of whole body average SAR was found to be approximately, 0.0227, 0.030 and 0.0616 W/kg. Again not my field but I doubt 120mW/m2 can result in 50% absorption (61.6mW) per kg of rat. That means 2 kg of rats would absorb 100% of the radiation, while obviously not covering a full square meter. Please correct me if I misunderstood something. I'm not saying that 2.4GHz radiation has no ill effects, there's tons of research on rats since the inception of the microwave, but it generally show changes at higher (and certainly more clear) SAR levels.

bjarneh 5y ago

There's more peer-reviewing on HN, than the actual peer-reviewing.

donw 5y ago
Peer review in and of itself is of limited value, and usually reveals cosmetic, as opposed by structural, errors. How many code reviews can be summarized by the letters "L", "G", "T", and "M"? Replication matters. The echo chamber of peer review much less so.
- bjarneh 5y ago
  > usually reveals cosmetic, as opposed by structural, errors I agree, science has become a form of writing and the peer-review will most likely figure out if you are familiar with that form.
coldtea 5y ago
Most actual peer-reviewing is bogus, facile comments, by people not even bothering to read the paper (when they're not in cahoots with the author and journal).

gonzo 5y ago

> when I think they mean dBmw (an absolute measurement). I think you may mean dBm or dBmW here. 0dBm == 1mW. The SI symbol for Watt is ‘W’ not ‘w’. At 2.4GHz, free space path loss is -41dB at 1m, so even a 20dBm radio and a 20dBi directional antenna (and assuming 0dB of insertion loss), the signal strength at 1m is -1dBm, or about 0.79 mW. At 3m, the free space path loss is nearly -50dB. Now the signal from the setup above is at -10dBm, or 0.1mW. https://ecfsapi.fcc.gov/file/10417871820142/2018%2BRF%2BRadiation%2BExposure%2BLimits%20(1).pdf https://ecfsapi.fcc.gov/file/10417871820142/2018%2BRF%2BRadi...

R0b0t1 5y ago

1800MHz is not that close to 2450MHz. Behavior in air is different, for one, and the properties that dictate this, the vibrational modes of atoms and so on, are extremely selective.

inter_netuser 5y ago
Not just atoms, you could be hitting something specific in terms of resonance at 2.45ghz. Maybe rats skull size is perfectly resonant at that frequency, who knows.
- hansel_der 5y ago
  2,45GHz ~= 12,2 cm wavelength resonance seems plausible
- accountofme 5y ago
  2.4GHz resonates with water. Thus why it is also used in microwaves to heat our food!
  - anotherhue 5y ago
    An urban legend. Microwaves cause heating across a wide range of frequencies.
    - coldtea 5y ago
      Not really: Consumer ovens work around a nominal 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in) in the 2.4 GHz to 2.5 GHz ISM band
      - detaro 5y ago
        "Microwaves" as in "the part of the electromagnetic spectrum we call microwaves". And as they correctly point out, that consumer ovens use a specific frequency has nothing to do with it being a resonance frequency of water, but it being a reasonable to use and legal frequency to do so. They would work on 1 GHz or 5 GHz too.

markenqualitaet 5y ago

Have they controled for coil whine and similar (inaudible to humans) artifacts? Might explain a difference in frequency "response".