Plastics decompose fast in water

In the first study to look at what happens over the years to the billions of pounds of plastic waste floating in the world’s oceans, scientists are reporting that plastics - reputed to be virtually indestructible - decompose with surprising speed and release potentially toxic substances into the water.

Reporting at the 238th National Meeting of the American Chemical Society (ACS), the researchers termed the discovery 'surprising'. Scientists always believed that plastics in the oceans were unsightly, but a hazard mainly to marine animals that eat or become ensnared in plastic objects.

'Plastics in daily use are generally assumed to be quite stable,' said study lead researcher Dr Katsuhiko Saido of Nihon University in Japan. 'We found that plastic in the ocean actually decomposes as it is exposed to the rain and sun and other environmental conditions, giving rise to yet another source of global contamination that will continue into the future.'

He said that polystyrene begins to decompose within one year, releasing components that are detectable in the parts-per-million range. Those chemicals also decompose in the open water and inside marine life. However, the volume of plastics in the ocean is increasing, meaning that decomposition products remain a potential problem.