A similar issue was raised when houses were first being wired for electricity.

Is your sister-in-law's mother aware that light has the dual nature of both particles and electromagnetic waves, including the infrared that radiates to and from the earth and all warmer than absolute zero objects such as your sister-in-law's mother and gas burner flames; that radio transmission (including AM, FM, TV, WiFi, Bluetooth, SMS, etc.) uses electromagnetic waves; and that the cosmic rays that continuously bombard the earth generate daughter particles that are also electromagnetic waves that routinely intercept our bodies (like all particles are, quantum-mechanically)? Even as I write this, trillions of neutrinos per second are passing through my body. The reason why these various particles/waves are rarely a health hazard is that they do not couple well to the body tissues, or are very weak. Sunburn is the greatest hazard for most from this partial list.

Perhaps your sister-in-law's mother had a more specific concern than electromagnetic waves in general. Not unreasonable questions can be asked such as: "Is the electromagnetic field that may be exposed around the edge of a pan base a hazard to electronic safety devices, such as heart pacemakers?", or, "Is the field strong enough at the cook's location to induce any effects on body tissues?" There have been answers posted here on these topics in the past, but I don't have the references at hand, so a search will be required to find them and any referenced supporting data. I am not aware of any such risks for normal cooking tasks.

The electromagnetic field lines are pretty well constrained to leaving and entering the coils under the glass much as the field around a bar magnet leaves one end and enters the other; the field coils are not matched to the air impedance such that the fields can propagate easily (like radio does). The field frequency is very low, in the 40 kHz region, and as such would require an enormous antenna size* to achieve propagation through the air. This is fine, because the coil's function is to couple into inductive iron and steel located close to the coil, and if the coil circuitry does not detect that the coupling is adequate, it shuts the hob down. This is not to protect the cook from errant electromagnetic waves, but to protect the circuitry and to avoid rapidly heating a misplaced spoon.

Perhaps your sister-in-law's mother has a reference of her own that asserts a hazard related to induction cooktops. I'm sure we would like to know about it.

kas

* See for example the article at

https://en.wikipedia.org/wiki/Very_low_frequency

This is something that gets discussed to death every six months or so. First thing to know is that there can be both wheat and chaff in the discussions that turn up in searches.

The "wheat" in this discussion is some research that:

(a) Tests with old-style "unipolar" pacemakers found some detectable interaction but no disruption when those pacemakers were implanted on the left side of the heart and the recipient was very close to an off-center pan on an induction burner in operation, (i.e., when somebody with one of those pacemakers has his or her chest virtually across the top of the pan or with the chest against the front of the stove while using a front burner). Other pacemakers and defibrillators seem unaffected (so far, anyway);

(b) Some generalized concerns arising from having yet another device with electro-magnetic fields in daily use (i.e., adding to the proliferating array of electronics that include tvs, bluetooth and wi-fi transmissions, computers, cell phones, RFID, implants on products, garage openers, loudspeakers, smart watches, and many, many other modern devices, not to mention the proliferation of use of medical devices including x-rays, CAT scanners, MRI, etc. and not to mention electro-magnetic fields from all the wiring many of us now have in our houses);

and

(c) a few unusual people who reportedly display truly extraordinarily high sensitivity to electro-magnetic fields.

For the legitimate scientific references on these subjects, you can start with the links collected at http://theinductionsite.com/radiation.php.

This is mainly the stuff of risk assessment and your own personal sensitivity to risk. For some folks, even the possibility of any risk, at all, is absolutely unacceptable. Others won't consider risks that seem insignificant to them. An example of this is with dishwashers. According to the National Fire Protection Association, residential dishwasher failures have been responsible for something between 900 and 1200 fire incidents per year and anywhere from 6 to 50 burn injuries per year over the last couple of decades. Some folks will look those statistics with a reaction like, "OMG, 1200 fires a year! I'm never, ever going to have another dishwasher in my home ever again. Those things ought to be banned." Other folks will look at the same statistics with a reaction like "There must be 90+ million households with dishwashers and .00000016% catch fire? That risk is too inifinitesimally small to be a concern to me.") A lot of the risk assessment on induction is in this vein.

So read the references and decide for yourself how you feel.

Be warned that general searching will turn up a lot of the chaff that I mentioned at the outset. This is noise from all sorts of "I heard from the Internet that somebody somewhere is an expert who said or believes that induction is bad because ..."

To put it simply, an undiscriminating search will turn up a lot of half baked and/or outright crack-pot ideas that get
passed on to folks as scientific truth and fears of mega-corporate conspiracies
to hide the supposed truths from a vulnerable public. Theories and
discussions assert ill-informed variations on theories including the following. Induction creates
ionizing radiation --- which is not so --- and ionizing radiation is akin to exposure to unshielded nuclear waste (which will give you cancer if you get too much of it). Induction (instead or in addition) also creates non-ionizing radiation because it uses uncontained microwaves (again, not so, but supposedly irradiates you and destroy all nutrients in your food). You can
get electrocuted using metal utensils with a pan on an induction cooker (absolute nonsense). Nobody with a pace makers can use induction because induction
stove use electro-magnets, they must produce horrendously strong
magnetic fields that are as bad or worse than an MRI. Induction fields are so strong they will destroy
the pacemakers of anybody in the room and probably the house. Every electric cook stove (not just induction) generates magnetic fields as do a lot of other kitchen appliances because they have transformers and/or electric motors (such as toasters, mixers, blenders and food processors) but induction is just one more long term toxic thing so we all should limit ourselves to raw food prepared with hand tools. Etc.,
etc. etc.

At some point, I'm sure we're going to see posts proclaiming that steel knives are poisoning us by leaching toxic metals into our food and what we really need for a true paleo diet is to chip our own blades out of locally sourced obsdian. :>)

You get the idea how people can be unnecessarily alarmed by internet blather.

Kas mentioned previous discussions here. If you are interested you could check out these threads which turned up in a quick search (I'm sure there are lots more on this, tho):

http://ths.gardenweb.com/discussions/2340686/inductionsafe-with-metal-implant-in-hand

http://ths.gardenweb.com/discussions/2327907/your-input-on-this-research-study-re-induction-safety

http://ths.gardenweb.com/discussions/2317940/induction-and-health-issues

http://ths.gardenweb.com/discussions/2251887/hazards-of-induction-stoves

http://ths.gardenweb.com/discussions/2693554/gas-or-induction

http://ths.gardenweb.com/discussions/2257715/reducing-emf-dangers

http://ths.gardenweb.com/discussions/2693554/gas-or-induction

http://ths.gardenweb.com/discussions/2347148/scientists-concerns-about-induction-and-gas-cooktops

http://ths.gardenweb.com/discussions/2342757/pacemaker-practical-info-needed

"Is the electromagnetic field that may be exposed around the edge of a pan base a hazard to electronic safety devices, such as heart pacemakers?"

My DH has a pacemaker, so the first thing I did when I was deciding to put in induction in my soon to be built house was to call the company that makes his pacemaker. We were told that it is perfectly safe to use induction with a pacemaker, as long as the pacemaker is at least 6" from the top of the induction area being used. In other words, you'd have to have a pan on the induction hob and then be leaning over the pan practically touching it for it to "maybe" have any effect on the pacemaker and even then we were told it was unlikely.

Thank you all for this great information. i appreciate it!!

Thanks for that, JW; I'm glad it was you and not me who took the opportunity to investigate the chaff.

Kas ----

Maybe I've spent too much time in the company of physicists. I wonder if the internet is empirical proof of the operation of string theory in the cosmos. An awful lot of stuff seems to come from dimensions other than the ones I live in. :>)