When plastic is burned, it can release potentially harmful fumes and chemicals into the air. While I don't have information on the specific composition or safety of the plastic lids used on Handi-Foil pans, it is generally recommended to avoid burning or heating plastic materials.
When using Handi-Foil pans or any other disposable aluminum pans with plastic lids, it is important to follow the manufacturer's instructions and guidelines. These lids are typically designed for covering and storing food, not for direct exposure to high heat or open flames.
If you accidentally burn the plastic lid on a Handi-Foil pan or any other cookware, it is advisable to discard the pan and lid. Inhaling the fumes from burning plastic can be potentially harmful to your health. Additionally, it is always a good practice to use cookware made from materials specifically designed for high-heat cooking, such as stainless steel, cast iron, or oven-safe glass, to ensure safety and avoid potential risks associated with burning plastics.