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Is my tea kettle poisonous?
May 28, 2006 1:24 PM   Subscribe

Is my tea kettle poisonous? I put the kettle on to boil, then was called away to face some kind of (I have a six-year-old) emergency. When I returned, the forgotten kettle had boiled away all of the water and had been probably been firing away empty for about ten minutes. Is that bad? Should I toss it? Why?
posted by cometwendy to Health & Fitness (30 answers total)
Why would that make it "poisonous"? Unless the kettle's got a plastic handle that melted from the heat (doubtful if it was just on the stove for 10 minutes) or is teflon-coated (though I can't imagine any kettle being coated with teflon in the first place), I can't imagine what toxins would be released simply by letting it get really hot.
posted by scody at 1:37 PM on May 28, 2006

If you tried to eat it, perhaps.
posted by Krrrlson at 1:40 PM on May 28, 2006

It depends on the construction of the kettle. Kettles that have a copper or stainless steel on bottom are probably ok. I'd be wary of one that's aluminum, or is aluminum with a wrapper of stainless, porcelain, etc. If it didn't ruin the pot completely (you'd know if it had), you're probably ok, but why risk it?
posted by hoborg at 1:42 PM on May 28, 2006

but why risk it?

risk what? Are you suggesting that an aluminum (or aluminum + stainless, etc.) kettle would be physically damaged from the heat, or would actually be toxic?
posted by scody at 1:45 PM on May 28, 2006

There's nothing wrong with your tea kettle.

If you repeatedly boil away water in it, you'll end up with scale on the bottom, minerals from the water that are let behind. (Same thing happens to electric coffee makers, for the same reason.) You can clean this off with vinegar.
posted by jellicle at 1:52 PM on May 28, 2006

I once saw a truly bizarre art installation, where some guy had bought hundreds of old metal teapots from thrift shops and cut them all in half and mounted them on the wall with the inside exposed.

I'm not sure where he got these things, or what kind of water supply that entailed, but the whitish mineral deposits inside the pots where in several cases inches thick. In some there was only a small pocket left for water.

I'm guessing the owners of these pots survived, or how could they have built up that much deposit?
posted by StickyCarpet at 1:52 PM on May 28, 2006 [1 favorite]

Happens to me a lot. You're fine.
posted by special-k at 2:04 PM on May 28, 2006

StickyCarpet - it's called limescale. I can't imagine it's toxic since pregnant women often crave and consume it.
posted by fire&wings at 2:17 PM on May 28, 2006

What's it made of?
posted by scarabic at 2:20 PM on May 28, 2006

(some do have plastic handles, paint on the outside, plastic whistle-lids... whatnot... I dunno). If it's made of anything that will oxidize, there may be significant oxidation, since, like a lot of chemical reactions, oxidation speeds up with heat. Rust shouldn't kill ya, but it could be nasty.
posted by scarabic at 2:23 PM on May 28, 2006

What scarabic said. You don't want to be drinking rust.

Is this a plug-in electric kettle with the heating coils inside? Or a sit-on-the-stove element type of kettle? If it's the former, I'd say pitch it and get a new one: chances of rust are high. If it's the latter, and you can't see any rust, it might still be safe.
posted by Fuzzy Monster at 2:32 PM on May 28, 2006

Reasonably good quality kettles are cheap ($10-$20) - I'd boil some water in it... see how it looks, smells, tastes... if it seems weird then toss the kettle.

No brainer.
posted by wfrgms at 3:22 PM on May 28, 2006

I will bet your life that it is safe. I mean, come on, what on earth could possibly be poisonous about it? And what's with this "rust could be nasty" meme? Fill it, boil it, dump it, and then use without a care in the world. Good god, it's not like the kettle is a toxic waste dump!
posted by five fresh fish at 3:29 PM on May 28, 2006

Your tea kettle was the same or similar in temperature when it was empty as when it had water in it. It's fine.
posted by cellphone at 3:34 PM on May 28, 2006

How much heat do you think your kettle was subjected to during manufacture? Oh, and what cellphone said.
posted by phrontist at 3:58 PM on May 28, 2006

Drinking rusty water will increase your iron, but is otherwise not a health problem, except is weird rare cases. Limescale is generally calcium and other minerals and is not a big deal. Scrub it out a bit, just to get rid of any off taste.

There is some concern that aluminum cookware contributes to Alzheimer's disease. Mostly a problem with acidic foods, but I stick with my Revere copperclad steel.
posted by theora55 at 4:00 PM on May 28, 2006

There is some concern that aluminum cookware contributes to Alzheimer's disease. Mostly a problem with acidic foods, but I stick with my Revere copperclad steel.
You've fallen for an urban legend.
posted by Rhomboid at 4:14 PM on May 28, 2006

StickyCarpet - it's called limescale. I can't imagine it's toxic since pregnant women often crave and consume it.

I have never heard this before. Fascinating. Do they dig it out of kettles and lick it off of faucets? Or is there some easier way to get it?
posted by PinkStainlessTail at 4:35 PM on May 28, 2006

comentwendy, I'm genuinely curious as to how you came to think your tea kettle might be poisonous. As I was re-reading your question it suddenly struck me that it's as odd to me as the Korean idea of fan death.

So did you happen to overhear some sort of teapot poisoning myth, or confuse it with the aluminium poisoning myth, or ... ?
posted by five fresh fish at 5:32 PM on May 28, 2006

He's probably thinking of teflon pans.

And the kettle won't be at the same temp when it's boiling water as when it's empty. It'll almost certainly be quite a bit hotter. Unless the heating element or whatever heats to 100C and no higher. Which would make for a slow-heating teapot.
posted by Ethereal Bligh at 6:15 PM on May 28, 2006

the empty kettle will be hotter. 1. water has a very high heat capacity. iron, not so much. 2. that phase change carries heat away from the kettle. 3. what happens when you sweat?
posted by Ethereal Bligh at 6:26 PM on May 28, 2006

Your tea kettle was the same or similar in temperature when it was empty as when it had water in it. It's fine.

That's not true. The water holds the temperature of the kettle to exactly 212F (at sea level). When the kettle is boiled dry, it gets a very great deal hotter than normal, and can indeed be damaged. If it has any teflon, toss it. High temperature releases teflon, which is quite toxic.... teflon fumes will make people sick and will kill birds outright.

A standard, metal kettle will be fine, though, no reason to throw it away. It may be softer than it was, and more prone to damage from being knocked about, but should still boil water fine.

As an ancillary experiment to prove what I'm saying ... fill a large paper cup with water and put it in a fire. The water will boil inside the paper cup, which will burn down to exactly the level of the water and stop. As the water boils down, the cup will burn with it, but anywhere that is touching water will survive nicely.

Metal conducts heat much better than paper, so a kettle in the same situation will stay right at 212F as long as there's water left. More heat applied outside will just boil more water, without raising the temperature of the kettle more than a tiny fraction of a degree.

This is why boiling a kettle dry is bad... it's exposed to a great deal of thermal stress that it's usually not designed for. As long as there's no teflon, it's not bad for YOU, just the kettle.
posted by Malor at 6:37 PM on May 28, 2006

I'd be a bit more concerned about the fire risks of leaving an empty container on the stove unattended, myself. My grandfather's neighbor nearly burnt her house down doing that.
posted by Atreides at 7:00 PM on May 28, 2006

You've fallen for an urban legend.

"urban legend" hardly means "Unfortunately, there is no clear-cut answer either to implicate or to absolve the role of aluminum in causing Alzheimer's disease." (from the link provided.)
posted by advil at 7:31 PM on May 28, 2006


1) Why would a kettle have teflon?

2) True, high heat releases toxic teflon fumes. However, EVEN IF she stood over the pot sucking them in she probably would have at worst gotten sick and more likely nothing would have happened. Teflon can kill birds, but that's because they are very sensitive to this and other toxic gasses. Infact, in my research I could only find 1 single documented case of a human being dieing from teflon inhalation. He worked at a plant that coated the pans and died from long term exposure. Regardless, assuming the fumes are all gone now, the pot still wouldn't be toxic to use.

I have to say this question is ridiculous. The poster should worry more about burning the house down, not about a hot kettle.
posted by crypticgeek at 7:33 PM on May 28, 2006

You can call it what you want. I call it an urban legend when someone gets it in their mind that one is related to the other, to the point where they suggest avoiding aluminum pans, even though there is no evidence to support this, and when prominent scientists in the field say things like
We do not recommend that people avoid aluminum cooking pans or aluminum-containing antiperspirants or antacids because there is little evidence that such lifestyle changes are helpful
In my opinion, the supposed relation between aluminum and Alzheimer's Disease is a simple case of neuromythology
posted by Rhomboid at 8:51 PM on May 28, 2006

I'm afraid we just can't answer this one without at least a little more info. I'm guessing that the chances are 95% that it's no big deal. If the thing was stainless steel or ceramic coated, I wouldn't worry much. If it was some piece of shit you needed to get rid of anyway... now you have a good passable excuse.
posted by scarabic at 9:37 PM on May 28, 2006

Most electric kettles have an over-temperature safety cutout that is designed to handle this exact situation. The kettle will get significantly hotter than boiling point but will not have destroyed itself or made itself unsafe.
posted by flabdablet at 1:32 AM on May 29, 2006

I had a cheap pot which I had something very similar happen to... I'm playing World of Warcraft (or something), think "Hmm, I should make some Miso Soup" ... go back to World of Warcraft... and then maybe an hour later "Oh yeah... soup..." The pot was warped but I've used it since. I can't speak for major long-term effects, but in the short term, it didn't make me sick.
posted by dagnyscott at 6:48 AM on May 29, 2006

If your teapot looks like this, it is almost certainly poisonous! Do not eat it under any circumstances.

posted by atrazine at 5:30 PM on May 29, 2006

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