Dockworkers, environmentalists, and the regional EPA office in Seattle joined forces yesterday to stop the first in a series of shipments of potentially toxic waste from Taiwan due to be shipped to Tacoma, Wash., this week, then on to an Idaho hazardous waste landfill. The waste was illegally dumped last year in Cambodia, where its presence started a panic that killed several people; it was then taken back to Taiwan. When word got out that some of the waste was being loaded onto a ship bound for the U.S., a dockworkers union in Tacoma contacted the company that owned the ship and announced that its members might refuse to unload the material. The company then removed the load. Enviros are criticizing the U.S. policy that allows foreign waste to be imported into the country.