The biggest and most important disadvantage of polyurethane leather is that despite requiring less resources to make, it does not decompose after use and therefore should not be regarded as sustainable! When products made of polyurethane leather go to landfill, after a very long time, they will start to break down. When this happens the polyurethane releases phthalates into the air which are harmful to breathe in. Yes, vegan leather products do not require animals to be harmed in order to be produced, however it can cause irritation in the lungs of humans and other organisms including animals.