Discarded chewing gum is a common eyesore, and removing it from city streets and sidewalks can be costly. A Mexican congressman wants to solve the problem by borrowing a concept widely used in environmental regulation: making the polluters pay. For more global science stories, visit: http://www.world-science.org/ NOVA is produced by WGBH in Boston. National corporate funding for NOVA is provided by The Boeing Company. Major funding for NOVA is provided by David H. Koch, the Corporation for Public Broadcasting, and PBS viewers.