This website lists the six synthetic or artificial fabrics to avoid because they may be toxic or harmful to some people. These include polyester and nylon. http://bodyecology.com/
The article recommends people to wear clothes made of natural fibres, such as cotton, silk, wool and linen. I have decided to discard some of my clothes from my drawer recently after reading about it, such as my shirts and shorts that are made of polyester.
I have read in some other websites such as this one http://www.ecologycenter.org/
This article says that studies have shown that polyester garments and undergarments may affect pregnancy health in women, and also affect fertility in men. http://blog.fashionandearth.