I do not know if this is true but if it is then its pretty scary.
This is how long it takes for items from your garbage to get assimilated back in the ecosystem:
"Orange peel (2-5 weeks)
Paper bag (1 month)
Cigarette butt (up to 5 years)
Leather shoe (45 years)
Plastic bottle (430 years)
Aluminum can (200-500 years)
Disposable diaper (550 years)
Glass bottle (Approx. 1 million years)
Plastic Grocery Bag
Styrofoam container (1 million years)
If this is indeed true, its reason enough to stop using plastic grocery bags.