Houston Chronicle: For years, Congress has promoted corn ethanol, touting its purported environmental benefit. Mounting data now suggest these assumptions were wrong. Expanded use of food for fuel is exacerbating environmental threats, including pollution in U.S. waterways. New data out this week on the growing “dead zone” in the Gulf of Mexico starkly highlight this concern. Dead zones are created when large amounts of nitrogen and phosphorous run off into warm waters, spawning algae …