Grill mats are made of fiberglass cloth coated with PTFE, which is inert – that is, chemically inactive, and used to coat nonstick cookware. Both materials are safe to use as long as the product is FDA-approved. You’ll come across grill mats with PFOA-free labels as well. Speaking of which, PFOA is a chemical, which is found to increase the risk of cancer, and was used to make PTFE. But, since 2013, it’s phased out of use.