Plastic use should be minimised. 

Plastic has a finite recyclable life some things such as aluminium can be recycled again and again but plastic can be recycled once or maybe twice. Also plastic doesn't rot, it does degrade- eventually into a dust. This makes me think that the whole world may one day be covered in a layer of plastic every thing could be contaminated.

Look at this BBC report from 2006: http://www.bbc.co.uk/radio4/science/costingtheearth_20061208.shtml