If you’re cooking for long periods of time, parchment paper is indeed safer than aluminum foil. Studies have shown that, if it is heated at high temperatures for long periods of time, particles of aluminum transfer to the food. You wouldn’t be able to taste it, but it is unhealthy. It’s important to note that bleached (white) parchment paper is unhealthier than even aluminum foil, so you should only use unbleached (brown) parchment paper.