PVC - present in virtually all areas of human activity, is a chlorinated hydrocarbon polymer - its basic building blocks are chlorine, carbon and hydrogen. These elements are obtained from sea salt (sodium chloride) and crude oil or natural gas, both of which are mixtures of hydrocarbons. PVC is a thermoplastic. This means that it softens upon heating and hardens upon cooling.
It was first made in 1872. However, the first PVC wasn't very good. When heated or exposed to sunlight, the molecules broke up and an acidic gas was given off. Decades later, scientists discovered that chemicals could be added which would make it stable and resistant to light and heat. This meant good-quality PVC products could be manufactured.
PVC was first used instead of rubber to insulate the wires in electrical cables. This was about 60 years ago, during World War II when rubber was in short supply. Since then it has replaced rubber for insulation and found many other applications. These days, it's the second most popular plastic in the world.
In more than 60 years of production and commercial use, PVC has contributed greatly to the development of modern life. It has also become one of the most thoroughly researched materials. Its manufacture is closely regulated and results of life cycle analyses published so far show that PVC is a safe product in its production, use and disposal.