Thanks for the dip into chemistry-land.
Very interesting about degradation catalysed by clays.
I agree that aquarium seal smells nasty. But you do have to admit that a lot of sensitive tropical fish live in aquariums sealed with it. So you can see their point; fish don't tolerate the chlorine we do in our drinking water, but they can live with a little bit of silicone off-gas or dissolved solutes or whatever.
From a low-level scan of Wikipedia, there also appear to be different types of silicone polymers.
Some of which use elements that I'm comfortable with. (I know simple, inorganic chemistry, but not much organic, so I tend to go with brute element analysis as a first step. Elements which can theoretically biodegrade seem safer than those that don't. I know that organic compounds can also be very toxic, I just don't know which ones are most dangerous, so I am a bit more lost there.).
But there are some silicone polymers that are made with chlorine, and polymers with chlorine are one category of organic compounds that ring warning bells for me. They tend to gum up living beings pretty good.
So there should be literature that distinguishes between different types of silicones. Maybe that's an important component in the 'food-grade' designation.
Product info should also give this - you can request an MSDS for any item that might be used in a workplace, and most places put a reasonable amount of info in there to be able to suss out which products they are using. Others don't ("a proprietary compound of X and Y").
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For the OP's question about baking and cooking, I prefer materials of known chemistry that I can understand.
Cast iron does this for me - if I cook with acid in it, I get extra iron in the food. Ok with me.
If I cook with oils, it polymerizes to a 'mars black' form of iron, and makes it non-stick. OK with me. (Mars black is not on the short list of pigments known to kill artists, or puppies, or anything like that. And while over-cooked polymerized cooking oils are not great for you, there are a lot worse things in the world.)
If I wash it with soap or alkaline cleansers, I lose the non-stick, but I can re-make it again. I might get some detergent effects in the remaining non-stick if I don't rinse. All pretty much normal levels of household hazard. OK with me.
Glass is also pretty much OK with me. I use glass jars for long-term food storage, and put hot foods into them (if they are Mason or tempered glass).
I think I might prefer unglazed terra-cotta, for routine cookware, if it's chemical exposure we're worried about. Even if it's harder to clean than glass.
(Glass is clear, but that doesn't tell you what's in it. Lots of things like lead can be included in clear glass. Not usually anymore, but still, I think glassware is uppity and pretending to be purer than it is. Bake-safe glass also has that little trick of lasting for years despite chips and scratches, then suddenly exploding. Also nobody knows whether to call it a 'fluid' or a 'non-crystalline solid.' It is devious, glassware. Watch it closely. Especially if the cat is nearby.)
Glazed ceramic and terra-cotta - usually OK with me. Must be marked 'food safe,' and I prefer muted oxide colors over glossy or bright ones, especially for interior linings. I think most food-safe glazed pottery is at least as safe as glass. But because cracked pottery can still be used, I take care not to let it soak in things or get gunky. A stained cracked ceramic dish may have weird stuff living in the crack; might be time to retire it, or just sanitize it (boiling water / dishwasher) routinely. Pottery usually safer than metal or plastic, however, for chemical exposure.
Mended pottery is usually now a pottery-polymer composite. I don't mend hot-dish pottery (mugs etc) because I don't trust the polymers to stay out of solution when heated.
Glazed ceramic / enameled steel are also pretty much OK with me, as long as the interior colors are inert ones like white or rust-red. (I don't trust some of the blues, greens, and other bright pigments in contact with food. And if they are using something other than glass as the enamel base, I don't want to know about it. So baked enamel on cast-iron or steel cookware is usually OK with me.)
Stainless steel is mostly OK with me. It has some metals I don't like, but the stainless, chemical-resistant alloy means they mostly don't escape into the food that much.
Copper is mostly OK with me. Although toxic in large amounts, it's not very reactive, and does some nice things to certain foods like egg whites. I don't think I'm getting much copper in my diet regardless of cooking with one copper pan occasionally. Also copper and brass water jugs kill pathogens with 1 day of water storage, which is pretty cool, if a little alarming because that means it's effectively a pesticide of some kind.
Aluminum is not entirely OK with me. Though its lightweight, it's a very reactive metal, meaning it will leap into my food at the least trace of acid. I see pitting over time on aluminum pans; it's also soft, and can be scratched up by cleaning, meaning you expose more aluminum to be oxidized or dissolved in acidic foods.
There was also that urban legend about the link to Altzheimers, which is a disease that has occurred in my family, and I don't want to increase my risk factors. However, aluminum in its oxidized state is one of the most common minerals on our planet, and we are pretty well adapted to deal with it. So, could be OK with you.
Plastic is not entirely OK with me. I do use it to store and transport cold foods. But I notice that it stains with red sauce, and don't want it leaching anything into that same red sauce. Reports are that plasticizers get into foods much more easily if it's greasy or oily foods, so I tend to put those things in glass, or at least cool them before putting them in plastic and then not store them very long.
Natural rubber is OK with me, but does not work for some friends (allergies). So, like walnut oil and peanut oil, it is one of those lovely things with lots of uses that I still don't keep around that much.
Non-stick is not OK with me. It doesn't work, doesn't last, can't be scrubbed easily, and it has that 'new car smell' that says weird polymers. I don't buy it, and hand-me-down pans often get re-purposed to storage bins if their non-stick shows any sign of degrading.
Silicone seems like plastic, which seems like a weird thing to bake with. So I probably would not buy silicone bakeware. I do have silicone hot pads, and spatulas, and do not have a problem with silicone lids on containers.
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When would silicone and plastics be OK with me?
I suspect these materials will be safer if well cleaned, and used with cold foods. (I have a silicone ice tray for star-shaped ice cubes; don't use it often, but it doesn't freak me out either.)
Body temperature is warmer, and there is the possibility of long-term exposure transmitting chemicals into fatty tissues and cell walls (fat-like structures). Embedding or carrying things in the body in thin-skinned mucus membrane areas seems risky. But on the other hand, I spend hours typing on plastic keyboards and wiping my nose. Which is pretty gross now that I think about it (the nose wiping more than the plastic).
I have never felt compelled to analyze the polymer content of my keyboard, or the paints that my wrists rest on beside it. We use silicone pads for ergonomic keyboards, too, and I suspect the health benefits (avoiding wrist damage) outweigh any possible 30-years-down-the-line uptick in some undisclosed risk factor, for most people. So it may also be a matter of pick-your-battles.
(I do not personally favor stuffing anything plastic into my body, anywhere. I don't even like wearing noseplugs, though I will tolerate earplugs to avoid pain. This seems as much a matter of personal preference as anything else. I will wear safety glasses for a lot longer than some friends, who are comfortable with the nose plugs but don't like glasses. And like that. I would be happy to discuss more gory details with the ladies in private.)
Very hot uses will make chemicals move and change faster, so baking in any polymer, or the machine oils on cast iron or stainless steel, would be relatively high exposure. As with microwaves, baking in any plastic is likely to maximize the release of any plasticizers, or stray polymers, or mold-release, or whatever might be there.
So when I get a new cookpan, I want to pull out as much plasticizer and mold-release compound and machine oil as possible, before cooking in it.
Stainless steel always gets washed with
hot water and detergent, to remove machine oil. Cast-iron gets scrubbed, and then sometimes baked to cook any residual grease (with a secondhand deep-fryer that had rancid gummy oils, I scrubbed it and then baked it until it stopped smoking to get rid of the rancid gels).
Inhaling volatile polymers sounds a lot more risky than eating them, and probably on par with having them injected/ surgically implanted.
So if I consider heat-treating the pan to avoid eating the gunk, I want to
make sure I am not breathing the gunk. Whatever gunk there might be.
If your
oven is vented, you could put the bakeware on a 400 degree baking cycle (stay well below its rated temperature, for an empty pan), and vent the volatiles out of the house.
If your oven isn't vented, keep the temp
below smoke point for any materials used, or rig up temporary ventilation. If you can smell anything, vent the house.
If you do this on a rainy day you will limit your contribution to air pollution; don't do it on a day with
local smog warnings.
Before/during the bake-in cycles:
I like the dilute bleach approach. Though vinegar is not always reliable to cut greasy polymers. Something like an alkaline scrub (baking soda or non-chlorine bleach), or hydrogen peroxide, might break down/extract any factory oils faster than vinegar. You could do both, on separate cycles, to be sure. I would be tempted to heat the pan with a vinegar bath in it, then heat it again with a baking-soda rubdown.
I also like the idea of greasing up the pan with used fryer oil, or whatever food-grade grease you can spare, and then heating it for a while, before wiping off and repeating.
Anything that gets pulled out by oils, should get pulled out by the sacrificial oils. Repeat two or three times with various combinations.
Wash the residue off with a strong detergent, and you should be a lot cleaner than you started.
I would, off the cuff, guess that exposure from a factory-new product is about 10 or 100 times worse than a slightly-used object.
So by pre-treating with all manner of likely food chemicals (acids, alkali, oils, maybe also a grease-and-flour treatment for starches), you are taking that initial exposure away and lowering the subsequent doses.
After years of use, a decaying, older object would increase the exposure rate again.
Any time a plastic polymer appears to change in texture, color (bleached out), stiffness (getting more/less flexible), or break down in any apparent way, that tells me it's not reliably inert. I don't want active polymer-decay products in my food, no do I want them breaking during use. So I would retire any plastic foodware that shows signs of aging (scratched-up, colors changed, over-heated, sun-bleached, etc).
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Why do silicone products need mold-release? Aren't they flexible
enough to come right off the molds? Or are these harder versions?
It could also be that if it's a two-part polymer system, the stuff on the outside of the casting is not a mold release, but unreacted polymer, or a combination of unreacted polymer and a mold-release gel or powder. All excellent things not to have in your food.
I do think that our lives are pretty safe, overall, these days. The number of people not dying of cholera, typhoid, pneumonia, starvation, freezing to death, annoying their violent neighbors, house fires, factory fires, lynchings, civil war, and the like, adds up to billions. (Plenty of people do still die of these things, but not nearly as many as survive them all.) Which means that worrying over the potential toxicity of a new polymer is a pretty low-key life decision.
If you like the pretty colors, go for it.
You are far more likely to be slowly poisoned or quickly eliminated by your car, or by doing anything while intoxicated.
If you are concerned about the big picture, fate of our world, and industrial pollution, bake less and eat more home-grown salad (no wrappers nor shipping nor storage power nor cooking
energy).
Spinning it in a silicone salad-spinner, if they make those, seems pretty harmless too.
-Erica
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