TPU is made from polyether, polyester, or polycaprolactones, while polyurethane is made from polyols and isocyanates. If there are monomers and catalysts left over from the polymerization reaction(s) and other processes used to create TPU, there’s a chance that these could pose a risk of toxicity. Additionally, other chemicals may be added to TPU which could compromise its safety. And, as TPU breaks down, it can produce unsafe degradation products including toxic gases and dust. Furthermore, like polyurethane, burning TPU produces irritant toxic fumes, meaning that any mattress made with TPU will probably have been treated with flame retardants.