Used, unwearable clothing was once used for quilts, rag, rugs, bandages, and many other household uses. It could also be recycled into paper. Now it is usually thrown away. Used but still wearable clothing can be sold at consignment shops, flea markets, online auction, or donated to charity. Charities usually skim the best of the clothing to sell in their own thrift stores and sell the rest to merchants, who bale it up and ship it to Third World countries, where vendors bid for the bales, then sell the used clothing.
There are many concerns about the life cycle of synthetics which come primarily from petrochemicals. Unlike natural fibers, their source is not renewable (in less than millions of years) and they are not biodegradable.