The west Texas smelting plant of miner Asarco Inc. [Asarco was purchased by Mexican conglomerate Grupo México in 1999] has been tagged as a "potentially responsible party" in a U.S. federal pollution probe that could lead to an expensive clean-up in addition to other environmental obligations the company is already dealing with...Lexi Shultz, legislative director of the Mineral Policy Center, an environmental advocacy group, said Asarco and Grupo Mexico are trying to avoid huge clean-up costs in Washington, Montana and elsewhere by stripping Asarco of assets that could be used to pay for clean-ups.