Even if clothing is made from natural fibers, or semi-synthetic fibers derived from plant-based cellulose, they have still been subjected to chemical treatments, such as dying and bleaching, and can leach chemicals into the ground if the landfills are not properly sealed. Incinerating the clothes releases these toxins into the air. Synthetic fibers are even worse, because they require a lot of resources to produce and are essentially a type of plastic made from petroleum, which take hundreds, to maybe a thousand, years to biodegrade.