While humans have used natural fibers for millennia – rayon – which is made from wood fibers with synthetic processing – was invented in 1894 and the first fully synthetic fiber nylon was invented in the 1930s.
Other wood-based fibers produced with synthetic processing include modal and bamboo.
Fully synthetic fibers – generally made from petroleum or coal products – are acrylic – polyester and spandex.
Toxicology research into clothing focuses less on the fibers themselves and more on the chemicals used in processing the fibers.
Even a simple cotton T-shirt requires numerous chemicals to bring it to market.