[HN Gopher] Microwave ovens and their hazards
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Microwave ovens and their hazards
Author : trifit
Score : 47 points
Date : 2022-03-16 20:19 UTC (2 hours ago)
(HTM) web link (www.ccohs.ca)
(TXT) w3m dump (www.ccohs.ca)
| 52-6F-62 wrote:
| Yes we need documentation like this.
|
| When I was younger I worked in a warehouse. In that warehouse we
| had a break room. In that break room we had a microwave that was
| _not_ in good working order. The mechanism that would stop the
| machine from emitting microwaves when the door was opened had
| failed, and instead of fully disabling the machine out of safety
| it would allow it to continue to run with the door wide open.
|
| One day a coworker had been heating up some food and wanted to
| check on it, so he opened the door while it was running and stuck
| his head inside. Right inside. I had to holler at him to stop and
| pull his head out. Of course he was in no immediate danger, but
| I'm sure rotating all those water molecules in your brain can't
| do much good... those things do bake potatoes after all.
| mark-r wrote:
| Radar operators in the Arctic learned that they could stay warm
| by standing in front of their antennas. The first microwave
| ovens were called "Radar Ranges".
| KineticLensman wrote:
| There is a long standing dispute between WW2 engineers at
| Raytheon vs. those at the UK's Telecommunications Research
| Establishment [0] about who was the first to cook sausages on
| a radar set.
|
| (I previously worked at one of the modern successor
| organisations to TRE. I distinctly remember as a very young
| software engineer being told by an elderly staff scientist
| that his purpose in life "was to help confound the Queen's
| enemies and keep the poor bugger on the battlefield alive
| whilst he did so")
|
| [0] https://en.wikipedia.org/wiki/Telecommunications_Research
| _Es...
| aeternum wrote:
| The fact that these guys are still alive is pretty strong
| evidence for how safe non-ionizing radiation is, even at high
| strength.
| 52-6F-62 wrote:
| At least when you're not sticking your head into a box that
| is meant to contain those waves and concentrate them in
| order to heat up water-laden organic matter.
| smegger001 wrote:
| in my experience they seem to be more efficient at super-
| heating ceramic plates than water filled organic matter
| which still manages to be frozen in the center
| yongjik wrote:
| It's all a matter of degrees. People love to bathe in
| sunshine, but when someone builds a mirror powerful enough
| to boil water, it would be wise to keep your head and limbs
| well out of the focus.
| louky wrote:
| My grandfather was an EE involved in early radar/microwave
| comm research and repeatedly used the beams to warm his hands
| and feet when in the field. He was exposed to who knows how
| much and developed serious sensory and circulatory problems
| later in life, as well as an unknown brain issue.
|
| He was also around some of the overly-exuberant government
| tests of troop exposure to the immediate after-effects of
| atomic fission.
|
| https://upload.wikimedia.org/wikipedia/commons/7/73/Exercise.
| ..
| agumonkey wrote:
| I don't know if that's just me, but I have a reptilian reflex
| to never put my head in any box or cavity of a powered device.
| 52-6F-62 wrote:
| A reflex nobody could fault you for having, to be sure.
|
| Leave the rapid heating radio waves for the roti.
| m463 wrote:
| I've often wondered about putting it between two bluetooth
| earbuds or next to a cellphone...
|
| I don't know what the orders of magnitude power are, but I
| wonder about power vs time.
| saalweachter wrote:
| Take a good look at your hands. Hold them both up, turn them
| over, study the fingers and the palms and the wrists.
|
| Now decide which one you could stand to do without.
|
| That's the hand you stick into cavities of powered devices.
| somebodynew wrote:
| The biggest danger is generally to your eyes because they
| contain significant water content but lack the circulatory
| cooling found in other parts of the body due to the need to be
| transparent. Looking into a running microwave with the door
| open can pose a cataract risk.
|
| https://www.fda.gov/radiation-emitting-products/resources-yo...
| bell-cot wrote:
| Oh, yes.
|
| Think of what happens to the clear "white" of an egg
| (proteins + water) when you heat it up.
|
| Which clear parts of your eyeballs (also proteins + water)
| would you be okay with that happening to?
| causality0 wrote:
| Interesting. I wonder if looking too closely into a fire
| carries the same risk.
| somebodynew wrote:
| Infrared eye protection is important for glassblowers
| looking at molten glass [1]. Back of the envelope math
| suggests that an occupation that required staring at an
| intense fire for long periods of time would violate the
| same workplace safety thresholds, but I have not been able
| to locate any studies that specifically investigated
| looking at fire.
|
| There are a surprising number of different jobs that
| involve staring at incandescence from molten glass or
| metal, but I think the most interesting is an operator of a
| disappearing-filament pyrometer [2].
|
| [1] https://www.sciencedirect.com/science/article/abs/pii/S
| 02755... [2] https://en.wikipedia.org/wiki/Disappearing-
| filament_pyromete...
| theamk wrote:
| I wonder how this happened. I repaired two (consumer-grade)
| microwaves, and both of them had 3 independent switches:
|
| - one was sending signal to controller
|
| - second was cutting power to something (presumably magnetron)
| when released
|
| - third was short-circuiting magnetron when released, it would
| cause fuse to blow if it ever got energized
|
| I assume the mechanical parts were aligned such that if you
| open a door, the second switch was released before the third
| one.
| skywal_l wrote:
| Keep in mind that microwaves have lower frequencies than
| visible light or even infrared.
|
| Radio -> Microwaves -> Infrared -> Visible light -> UV -> X
| rays -> Gamma rays.
| walterbell wrote:
| Consumer microwaves use the same frequency as WiFi (~2.4Ghz) and
| leakage can be measured with EMF meters.
|
| We need an open-source database with test measurements of
| microwave ovens: - new devices (does max leakage
| vary by country?) - annual measurements of door seal decay
| syntheticnature wrote:
| Worth noting that most microwave ovens are made by two
| companies (only one, in the US), other than some high-end
| models.
|
| See
| https://twitter.com/wirecutter/status/1263549250719416321?la...
| bri3d wrote:
| Panasonic microwaves besides the very cheapest ones are
| unique to Panasonic and much better than the Midea models. I
| no longer own a microwave (due to kitchen space, not
| ideological opposition) but when I did, the Panasonic
| microwave I owned was noticeably better in every way than any
| microwave I had owned prior (which it turned out were all
| probably Mideas).
| aetherspawn wrote:
| Imagine being able to get a product reliable at that scale.
| mutagen wrote:
| I have a 5 year old microwave purchased from a retailer with a
| reasonable expectation of quality (Costco) with no visible
| issues with the door seal that significantly interferes with
| 2.4 Ghz WiFi. I'm sure my neighbors don't enjoy the occasional
| internet issues that must result.
| aetherspawn wrote:
| Yeah, I was hosting a zoom call once and everyone got kicked
| off immediately when my flatmate used the microwave to heat
| up his lunch.
| layer8 wrote:
| Also Bluetooth. My microwave tends to interfere with my
| Airpods.
| DantesKite wrote:
| I find dishwashers to be surprising dangerous. They can catch on
| fire from the heating element and their failure rate is
| astonishingly high.
| buescher wrote:
| I've met folks who've worked in that industry that won't leave
| one running unattended.
| 323 wrote:
| Getting burned when taking the food out is a far bigger risk.
| oceanghost wrote:
| I know this is tangential-- but does anyone know what the normal
| failure modes of microwaves are like?
|
| 20 years ago I microwaved some leftover macaroni and cheese from
| just a few seconds-- and it came out absolutely charred.
|
| I was confused but then noticed the microwave making an awful
| sound--a low rumble--it wasn't supposed to be on at all. Then the
| sparks started, then the smoke. Unfortunately the plug for it was
| behind a refrigerator so I ran to the electrical panel to turn
| the house power off.
|
| I figure some mosfet or something that controlled power must have
| failed closed or something. It most likely would have burned the
| house down if I hadn't happened to be right there.
| tejohnso wrote:
| Sabine Hossenfelder has a great explanation of 5G controversy[1]
| that is somewhat relevant. Explains why it is probably not
| dangerous, but also indicates why some additional study is
| warranted.
|
| [1]: https://www.youtube.com/watch?v=FBsP-bmDLOo
| account-5 wrote:
| I remember when I was younger looking into a microwave that was
| on, after the door had been smashed (don't ask). I remember my
| vision going all wavey, proper freaked me out. From this article
| it sounds like the water in my eyes was being rotated, which is
| kinda freaking me out again.
| jcl wrote:
| Wow... that's scary. But I think that when the article talks
| about water being "rotated", it's talking about individual
| water atoms, whose rotation would be too small to see.
|
| I imagine that the waviness would actually be due to the change
| in refraction due to the microwave's uneven heating -- like the
| waviness seen in the air just above a hot road, or the faint
| ripples seen at the bottom of a pot of cold water, when you
| start to heat it on a stove.
| exogen wrote:
| What's the latest science on microwaving plastic containers? Many
| now say "microwave safe" on them... did something change, like
| the research or the plastics used?
|
| Many of my friends still refuse to do it, but I'm not sure if
| that's still well-founded. My thought process is: well, the
| lawyers let 'em explicitly print "safe" on there... so they must
| be pretty damn sure.
| m463 wrote:
| I think the distinction people need to make is between heating
| in plastic and cooking.
| wyldfire wrote:
| The safety they're referring to is whether the container will
| melt. But plastic leaching into foods is still a problem as far
| as I know. So I use glass containers for leftovers that I take
| to work, for example.
| tejohnso wrote:
| I don't think they have to be pretty damn sure that they're
| safe.
|
| They only need to be pretty damn sure that they can't be proven
| to be liable for damage in a court of law.
| macintux wrote:
| When I was in my teens, we took a class trip to a nuclear reactor
| being built (never completed) in southern Indiana.
|
| I've long regretted I didn't have a camera with me to capture the
| large sign on one gate that read (paraphrased): "Danger:
| Microwaves on premises"
|
| I wasn't sure (still am not) whether they were referring to
| something industrial, but the thought that household microwave
| ovens at a _nuclear power plant_ were sufficiently hazardous to
| require warning signs like that amused me.
| dijonman2 wrote:
| The sign was most likely for pacemaker patients.
| ortusdux wrote:
| Are modern ones still susceptible?
| Nextgrid wrote:
| Aren't they encased in some bio-compatible metal,
| essentially making them a faraday cage that should be
| immune even to direct exposure?
| mark-r wrote:
| I believe they use microwaves for inspecting the welds on pipes
| and such.
| 52-6F-62 wrote:
| That's usually x-rayed if it's critical infrastructure AFAIK.
| Dad was a pipe fitter for Imperial Oil.
| laurent92 wrote:
| Depends on the size of the cracks you want to observe. For
| aircraft they use ultrasounds. I assume you dad used x-ray
| because methane and H2 are extremely small (they can't be
| contained in, for example, water pipes, so the same goes
| for diagnostics and wavelengths).
| naoqj wrote:
| smegsicle wrote:
| is this anti-science, since microwaves are non-ionizing therefore
| cannot cause cancer or any other ill effect at low doses?
| tlavoie wrote:
| From, well, reading the article, I'd say no.
| moltke wrote:
| Careful observation and investigation is never "anti-science"
| by definition.
| somebodynew wrote:
| The article seems to be focused on the potential risk of
| interfering with medical devices using the same frequencies for
| communication. The more obvious danger of a microwave oven is
| that you must not stick your hand inside a microwave with a
| defective door sensor while it is running as it will cause
| heating in the same way that it can boil a cup of water.
|
| I will note, however, that the statement "microwaves are non-
| ionizing" does not automatically imply the common follow-up
| that "the absorption of microwaves cannot have any chemical
| effect other than indirectly through heating". This is evident,
| for example, in that proteins in the human eye undergo a
| chemical change in response to absorbing non-ionizing red
| light. Whether there is such a thing as a non-thermally
| microwave-driven chemical reaction is an open question in
| chemistry [1].
|
| I feel the need to clarify as an addendum that nothing in this
| post suggests any danger associated with the use of low power
| microwave radiation from consumer wireless communication
| electronics.
|
| [1] https://en.wikipedia.org/wiki/Non-thermal_microwave_effect
| nimbius wrote:
| a major hazard missing from the article: high voltage
| transformers and capacitors inside can easily generate and store
| north of two-thousand volts. metal scrappers should take care to
| de-energize the circuit before diving in.
| janitor61 wrote:
| Newer microwaves don't use bulky HV transformers + voltage
| doublers for the magnetron anymore and instead use high
| frequency power supplies + step up transformers, and are
| noticably lighter
| someguydave wrote:
| Yeah that plus they often contain beryllium oxide which is
| dangerous to inhale as a dust.
| duskwuff wrote:
| My understanding is that this risk is overstated. BeO dust
| can be dangerous, but new microwaves no longer use it as an
| insulator, and the amount of dust which is likely to be
| produced by breaking the insulator in older microwaves
| (rather than deliberately grinding it to a powder) is
| minimal.
| agumonkey wrote:
| I had the shameful experience of breaking on of this rings.
| I got so scared from hearing about BeO that I mailed a
| bunch of safety hazard chemists and doctors. Most of them
| told me BeO is not used anymore in most kitchen appliances
| MWO and that it's most probably AlO which is enough to
| dissipate consumer devices' power. BeO was used in high
| wattage or military devices. After digging magnetrons
| manufacturer data sheets I found mentions of AlO and
| Chromium but no BeO.
| agumonkey wrote:
| Caps shock can happen so easily. Lots of tutorials online on
| how to make a discharge rod.
|
| I still have a dozen to make a 10kV ladder one day.
| toothpicked wrote:
| UHF microwave gun: https://www.youtube.com/watch?v=FIU8WZR9DNA
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