The most common toxic chemicals encountered on smart textiles and wearables, as well as on traditional fabric substrates are being presented along with health hazards and diseases reported for humans at various phases of the products lifecycle. The environmental impacts and the ecotoxicity related to end-of-life are briefly discussed. The chapter gives a general overview of the toxicity assessment methodologies and the existent regulations and policies, pointing out the weak aspects regarding the sustainability of smart textile products that have to be addressed in the near future.