Pure styrene is a colourless, clear, odourless, toxic liquid that evaporates easily.
Most styrene is synthetic although some styrene occurs naturally at low levels in a wide range of foodstuffs, such as fruit and nuts. Styrene began to be manufactured on a large scale in the 1930s. Huge quantities are produced each year as styrene plays an important role in the manufacture of products such as rubber, resins, plastics, fibreglass, car parts and carpet backing. Research indicates that humans breathing in high levels of styrene over a short time will suffer nervous system problems such as muscle weakness and depression. Animals exposed to styrene over a long period have suffered liver damage.