Using pennies has long been recommended by reputable cookbooks. Is there really a risk at 375 degrees F? I would think the everyday fumes from an unventilated gas oven are a much more significant problem, and that's fairly common in many parts of the US.
Anyway, I've done it a hundred times, and my brain and lungs still work good-ish?
Zinc boils at 1,180 K, so its vapor pressure should be negligible at room (300 K) or kitchen oven (500 K) temperatures. I suspect the GP comment is misapplying advice from a different context, like arc-welding.
(And a penny doesn't really have exposed zinc, I understand: its plating is pure copper).
I'd also note the combustion elements of stovetop gas burners are often brass (copper-zinc).
Good to know! I had never read that America's Test Kitchen actually recommended them. I heard pennies minted after 1982 had too thin a coating of copper and when scratched would release zinc. I guess you need much higher temperatures though. Ha! I've always just used a bag of dry black beans and recycled them for years.
Maybe if you had clean uncirculated pennies and lots of them(why?) but using pennies from my local gas station in my pies? How about no..... And washing them seems not worth the effort when a bag of dry beans is 70 cents .
They're easy to clean, and they don't come in direct contact with the dough at any point. America's Test Kitchen found that pennies work better than beans due to how they conduct heat. If you don't like the idea, that's fine, no one's forcing you.
Anyway, I've done it a hundred times, and my brain and lungs still work good-ish?