According to a study from 2012, "aluminum can leach from the foil into your food". It's especially true for spicy and acidic foods. Important this time of year for BBQ. You can always use this trick: line the foil with parchment paper first. Your food isn't touching the foil itself, so no aluminum can leach into it. OR....cheap product I found: Others to remember: 1. Plastic wrap that's not FDA "microwave-safe". Unless your plastic wrap is marked "microwave-safe," don't microwave it — it could leach BPA and polyphenols into your food. 2. Plastic takeout containers that aren't FDA "microwave-safe". Again, unless a plastic container is marked "microwave-safe," you're better off heating your food in something else. 3. Styrofoam that's not marked "microwave-safe", Especially if you're reheating oily or greasy foods, microwaving Styrofoam can cause it to melt. 4. One-time-use plastic containers. Plastic containers for yogurt, margarine, etc., aren't made to withstand the heat of the microwave and can melt. 5. Old mugs and ceramics: Some mugs and ceramics made in the 1960s or earlier are glazed with substances that can leach dangerous chemicals into your food. They can also react badly to the heat of the microwave, leaving you with burnt fingers when you try to retrieve it.