Enviros are cheering a decision by an international environmental panel to investigate Mexico’s handling of an abandoned lead smelter in Tijuana that has become a symbol of pollution problems along the U.S.-Mexico border. The Commission for Environmental Cooperation, established by a side accord of the North American Free Trade Agreement, agreed to compile a report on whether Mexico failed to enforce its own environmental laws by not demanding that property owners clean up some 6,600 tons of hazardous material at the smelter, which activists say is endangering nearby residents. Although environmentalists praised this move, they have long criticized the commission for acting slowly and accomplishing little.