Polyethylene and PVC today typically are made from extracts of natural gas rather than petroleum, but pricing still goes up and down with the oil market. Added cost pressures have arisen from this year's earthquake and tsunami in Japan, which knocked some processing plants offline. You can supplement U.S. PVC production by getting it from China, but plants there make a dirty product that requires a lot of titanium dioxide to whiten it?Cand titanium dioxide is in short supply. Meanwhile the recession has slowed business at the flooring and cabinet shops that generate most of what becomes wood flour.