I have a kettle on the stove I use to boil water for coffee, ramen noodles, etc. It appears to be made out of stainless steel. While cleaning it today, I notice that it is beginning to rust under the lid where the steam comes out.
How bad is this for my health? Should I be throwing the whole kettle out or will it still suffice for boiling water? If a little rust isn’t going to be a problem, what then is considered ‘too much rust’?
Walk it off 
It’s probably harmless in small amounts, but in large amounts, it will be absorbed by the internal tissues and “electrocute” your organs. That’s bad.
Rust (iron oxide) isn’t toxic. You’ll be fine. Too much rust is “a hole in the kettle”.
Seriously?
Bayesian. You’re a “noob” here. In General Questions, we expect rather more serious answers. Once the question has been answered, “joke” answers are pretty much ok.
No harm, no foul.
samclem, Moderator, GQ
Just to clarify my earlier answer, by the way, it is possible to get iron poisoning, but it’s tough. Usually happens with vitamins. The amount of iron leaching into your food from cast iron pans or a rusty kettle is going to be very small in comparison to the dose you would need for iron poisoning.
Iron oxide has an LD-50 of >10000 mg/kg. So an average adult could likely eat a pound of it without serious consequences.
Moreover, if the sort of rust that forms on cookware were toxic, the chances are pretty good that we’d find something else to make cookware out of, like we did with pewter.
What about the cumulative effect over time? I read years ago that rust or minute particles of metal, such as that created by running a knife over a sharpener or sharpening steel, get absorbed into tissues and stay there for the rest of your life, possibly resulting in a carcinogenic effect over time.
I don’t know for a fact if that’s true or not, but it’s such a simple matter to wipe the blade and clean or replace the pot or pan once rust begins to show up that I always just do that.
I’ve also heard that pans with Teflon coatings, when they begin to flake off, become poisonous and should be discarded. Again, I don’t know if it’s true, but why take the chance? I just don’t like the idea of ingesting metal or synthetic materials if I can avoid it.
One of my favorite Mr. Wizard episodes was the one where he showed the form of iron that we eat. He took one of those huge boxes of corn flakes, mixed it with water and stirred it with a magnetic stirrer for hours. The result; a huge clump of iron filings. The iron you get in food is IRON.
True, if you actually meant to say that the iron or steel is broken down and turned into useful things like red blood cells, and that people generally get cancer while they are living.
Our bodies are generally very very good at finding stuff that shouldn’t be there and dealing with it in one way or another. Nutrients, especially. There aren’t tiny metal particles hanging around in your body from your mom sharpening the knives when you were 3.
The exception is if you’re one of the 1 in 300 or so with hemochromatosis, a (usually hereditary) disease which causes the body to absorb iron much more efficiently than normal. In that case, you probably want to cut down on your dietary iron (in addition to giving blood frequently), which would mean not using cookware with exposed iron surfaces (especially rusty surfaces).
EDIT:
This is the case if it lists “reduced iron” in the ingredients list: “Reduced” basically just means “not oxidized”, or in the metallic form. There are other forms iron can be found in in foods, though.
When I was a kid, there was so much iron in the spring water that all the glasses were stained red. Didn’t do us any harm, but we couldn’t keep a drip coffee maker, but that may have been calcium, not the iron.
Really?!
Really?!
Easiest way to get rid of rust on stainless steel is to use BarKeeper’s Friend. Rub it on as a paste, let it sit for a few minutes, scrub it right off. It also repassivates the steel so it isn’t as likely to rust again.
Is it that hard to believe that iron is iron?
I too grew up in a home in which everything from the bathtub to the dishes to our clothing would get tinted red from rust in the water. I still hate the idea of doing laundry at my parents’ because I don’t want my nice white shirts to get stained.
Not at all! It’s the amount. I never thought that there’d be enough iron in a box of cereal to actually form lumps of the stuff. I’m not knowledgeable when it comes to food and nutrition, but I’d always sort of assumed that the amounts were VERY small compared to the actual volume of the food.
I’ve never heard of that. That’s really fascinating. Is it from the local plumbing (as in, the pipes of the house) or is it basically like that for the entire local community? I don’t know, it just seems like the sort of thing someone would complain about to the local utility companies or something. 
I’d imagine one of those huge boxes of cereal would have a couple hundred milligrams of the stuff. If this site is to be believed, it would work out to almost 350mg of iron per 43 oz box of Kellogg’s Corn Flakes. Not a ton or anything, but more than enough to see. I am assuming ‘huge clump’ is a bit of hyperbole.
As for the house water. We lived in the country so there was no utility to complain to. Like most people who live in a rural area, our water was directly pumped from a natural aquifer.
This raises the question…If one is iron deficient would eating (and/or drinking) from rusty cookware be beneficial? What if one took to eating exclusively from rusty cookware, could they skip the iron supplements altogether?
I am prejudiced against iron supplements…nasty little things! Rusty food sounds like a viable alternative to me. 
Cecil has mentioned iron-fortified cereals at least once:
http://www.straightdope.com/columns/read/676/do-iron-fortified-cereals-really-contain-iron-filings
I wasn’t joking. I probably should have explained better. For example, in the autosomal recessive disease Thalassemia, the blood is constantly being broken down; the only way to rectify this, other than bone marrow transplant, is to transfuse fresh red blood cells (RBC). The problem is, the RBC is still being broken down at a higher level than what is normal for an adult. If not transfused with RBC, the patient suffers from anemia and constant bone fractures. The side effect of the elevated levels of iron, sometimes enough that iron aggregates in the bloodstream. The body needs iron, but over the years of constant over-the-limit iron in the body, it will take its toll. Back before Desferal was invented for use as a iron chelator, blood transfusion was essentially a death sentence. But in normal adults, it’s very hard to achieve the levels needed to cause serious damage. That said, it is still possible. Please read this link.
I am not a medical doctor, just someone with some colloquial knowledge.
:rolleyes: What have you read lately?
Easy enough to wash a blade after sharpening. However, while replacing cookware at the first sign of rust may be a simple matter, it isn’t free. If one is budget-minded, then it makes sense to dig for the truth to find out whether the expense of a replacement policy like that is justified by the risks.
Because it might not be true, and new cookware ain’t cheap.
Metal? Check the ingredient list on common multivitamin pills. Here’s what I found in Centrum:
calcium
iron
magnesium
zinc
copper
manganese
chromium
molybdenum
potassium
nickel
tin
vanadium
Lots of metals are vital nutrients. Some people take pills to get enough iron in their diets; all you have to do is drink tea from your rusty-ass tea kettle.
As for synthetic materials…if you’re going to ingest one, Teflon is probably the best choice. Overtemping a non-stick pan is bad because it can generate toxic fumes, but if it’s just flaking off of the pan (e.g. you used metal utensils on it), there’s not much to worry about.