Waste!

[...]Some waste management experts^[who?] have recently incorporated a 'fourth R': "Re-think", with the implied meaning that the present system may have fundamental flaws, and that a thoroughly effective system of waste management may need an entirely new way of looking at waste. Source reduction involves efforts to reduce hazardous waste and other materials by modifying industrial production. Source reduction methods involve changes in manufacturing technology, raw material inputs, and product formulation. At times, the term "pollution prevention" may refer to source reduction.[...]http://en.wikipedia.org/wiki/Waste_hierarchy

http://en.wikipedia.org/wiki/European_Waste_Hierarchy