China Forces U.S. Cities to Change SpecsChina, one of the world’s main importers of recyclable waste, is rejecting shipments that are more than 0.5 percent impure, so loads contaminated by a greasy pizza box, disposable coffee cups and the odd plastic bag could end up in the local landfill instead. Most single-use cups, for instance, are lined with a fine film of polyethylene, which makes the cups liquid-proof, but also difficult and expensive to reprocess. Most waste management facilities will treat the cups as trash. Since China banned impure plastics, many U.S. municipalities no longer accept plastics numbered 3 to 7, which can include yogurt cups, butter tubs and vegetable oil bottles. Another contamination culprit is food residue. Washing out food scraps from recyclables can be just as important as putting the appropriate item in the recycling bin.