Audro

Except for the small amount that’s been incinerated - and it’s a very small amount - every bit of plastic ever made still exists, Moore says, describing how the material’s molecular structure resists biodegradation. Instead, plastic crumbles into ever-tinier fragments as it’s exposed to sunlight and the elements. And none of these untold gazillions of fragments is disappearing anytime soon: Even when plastic is broken down to a single molecule, it remains too tough for biodegradation.
Truth is, no one knows how long it will take for plastic to biodegrade, or return to its carbon and hydrogen elements. We only invented the stuff 144 years ago, and science’s best guess is that its natural disappearance will take several more centuries. Meanwhile, every year, we churn out about 60 billion tons of it, much of which becomes disposable products meant only for a single use. Set aside the question of why we’re creating ketchup bottles and six-pack rings that last for half a millennium, and consider the implications of it: Plastic never really goes away.

(Charles Moore) http://www.bestlifeonline.com/cms/publish/health-fitness/Our_oceans_are_turning_into_plastic_are_we_2.shtml