In 2007, TNO Built Environment and Geosciences was commissioned by Stichting Disposable Benelux (STB) to conduct a study on the environmenta impact of single-use paper cups
and PET cups and reusable drinking systems in Western Europe. Paper Cups
were seen to be least burdening the environment. Find the TNO Report here
Now that we have Biodegradable Paper Cups, things are even sweeter, no that doesn't mean you can now litter at will, bio cups mean at least they are compostable and don't take months and years to decompose, and thus are a lesser threat to mother earth.