A group of workers has filed a class-action lawsuit against the companies hired to clean up after the World Trade Center attack. The workers claim they were exposed to toxic fumes and debris at Ground Zero. The lawsuit, which also names the entities that leased and managed the trade center, was filed on Friday in federal court in Manhattan and announced yesterday. The companies have not yet responded. The plaintiffs also intend to sue the City of New York, the Port Authority of New York and New Jersey and the federal Environmental Protection Agency, David E. Worby, the lawyer for the workers, said. He was joined at a news conference by 13 people who he said had physical ailments directly related to their exposure to what he said were 9/11 toxins.