No. Do you think the manufacturer would overlook exhaustive testing for just this kind of destroy-the-business lawsuit possibility? It’s likely you could scrape off the lining with a chisel and eat a few grams of it without the slightest effect, other than some psychosomatic nausea and some odd black specks in your poop a day later. You’re basically eating plastic, and plastics are generally pretty inert.
Chemical harm to you comes overwhelming from small molecules, or even single atoms, because these can…
(1) Run the gauntlet of your digestive system, which is a pretty robust chemical environment. Your stomach grinds things up with a healthy dose of strong acid – you know it’s strong because it burns like heck when any of it gets up into your tender esophagus through acid reflux. Your intestines then further do a number on any organic molecules with a variety of effective enzymes that chop up proteins, fats and starches into their harmless components. (The famous example being that you can, within limits, eat rattlesnake poison without harm, because your digestive system shreds the poison molecule into harmless bits.) Small molecules, on the other hand, are immune to digestive enzymes – there are no bonds to break – and can much more readily stand low pH.
(2) Slip through the gateways guarding entrance to your circulatory system, e.g. get through the lining of your intestine, stomach, or mouth and enter your bloodstream.
(3) Slip from bloodstream into your cells, and
(4) Chemically react with a variety of molecules inside your cells, thereby disrupting their function and possibly causing cell death.
So as a broad rule, you should allow your fear of chemicals to be inversely proportional to their molecular weight. Things like CO, HCN, NaCN, Cl2 – extremely deadly. Bigger things like bigger proteins, foodstuffs, whether burnt or old or partially digested or whatever, are far less likely to be a problem, except in the weird special case of designed poisons, like venoms and plant defense agents.
A still bigger sensible worry are heavy metals, like lead or mercury. Here you have single atoms which can, alas, catalyze a very wide variety of noxious and potentially deadly chemical reactions once they get into your cells, and which, of course, are entirely immune to any digestive efforts. Notice also that I said catalyze – the metals are not even consumed by such reactions, and can go on doing the chemical damage essentially forever. Very tiny doses of heavy metals can have evil chronic effects. You definitely want to avoid all contact with heavy metals in your food or water. So wash your hands after you do some soldering, and if your water comes from a well, have it tested every now and then.
One reason people are concerned about burning food, by the way, is in this same vein. Cooking is chemistry, of course, a form of prelminary and very crude physical (breaking up the big structures) and chemical (oxidizing the big molecules) digestion. All very fine, and makes the food tastier and easier to digest.
But if you burn the food you are doing the chemical digestion bit a lot further – you are making unusually small molecules out of the large molecules in the food, and keep in mind what I said above about the smaller the molecule the potentially bigger the problem.
Your food is largely made of carbon, hydrogen, oxygen and nitrogen. When you burn it to a crisp, the H and O tend to be driven off as water, the N to some extent as N2, and you’re mostly left with carbon – charcoal. Pure carbon, i.e. graphite, is harmless, but along the way to carbon you can form lots of interesting small hydrocarbons, some with significant nitrogen-containing groups in them, and some of these can be quite chemically reactive in evil ways. The flat rings of aromatic carbon compounds, for example, are particularly good at sliding in between the rungs of DNA and mutating it, which is why many of these molecules, like benzene, anthracene and friends are powerful mutagens and in some cases carcinogens. Having a little nitrogen in there tends to enhance its reactivity, too.
Essentially, when you burn your food you make small quantities of the same stuff that a fossil-fuel power plant makes, and sends up the stack, or your car makes and sends out the tailpipe. Some of these are, indeed, not good for you. Of course, you make exceedingly small quanities of them at one time, so unless you really go to town all the time, it’s not likely to be a big worry.
Still, if you’re the kind of person who freaks out about a big coal plant ten miles up the road, you might not want to burn your cheese very often.