Polystyrene has long been of concern to environmentalists due to its very slow rate of biodegrading. It is chemically inert, but burns quite easily. All this means it tends to stay in the environment till it is burnt and burning releases toxic chemicals. It is not surprising than there has been much interest in recycling the product.
There is a general misconception that polystyrene only refers to the white foam (EPS) used for packing materials. In fact this is not even the most common form of the product. The foam (or Expanded Polystyrene) is the low density form of the material. Polystyrene can be used to create many plastic items. It has been used in CD cases for decades, and can be recycled into clothes hangers, toys, rulers, frames and had been used to make furniture.
Polystyrene is not safe when it comes to cooking, where the same safety issues of burning come into effect. The toxic chemicals in foam can get into food, though the amount is small and it take many years of continued use before health is affected. Nonetheless polystyrene should not be burnt at normal temperatures or used in microwaves.
Interestingly polystyrene can be incinerated safely at extremely high temperatures, above 1000 degree Celsius. At this temperature the only chemical products produced are water and CO2. Given the right setup this would be a useful fuel for power generation, care must be taken, however, as burning below this temperature causes the release of many toxic chemicals.
IS Recycling is a great interest to those wanting to find a use for the material. What has previously been regarded as litter could potentially be turned into useful plastic items. Unfortunately, the logistics of this are difficult. Foam Recycling Equipment was expensive, and the collection of foam was difficult due to its bulk. This is largely changing due to the lowering cost of the EPS Recycling Machine, and the ability for companies to compress the material before transportation.
Recently it has been discovered that polystyrene can be eaten and successfully digested by Mealy worms. So far no side effects or problems have been uncovered with this; the mealy worms are healthy and produce no toxic by-products. When properly collected polystyrene many cease to be an environmental problem; it can be reused or destroyed in several safe ways.