A US company specialising in the clean-up of hazardous wastes is seeking US$6.3m in compensation from the Canadian government over Ottawa's ban on the export of polychorinated biphenyls (PCB) waste. The claim, filed under the investor-state arbitration provisions of the North American Free Trade Agreement (Nafta), charges that Canada's 1995 ban amounted to an expropriation of the business of S.D. Myers, an Ohio-based company.