The Globe and Mail reports in its Thursday edition that McDonald's took steps on Wednesday to reassure customers about the safety of its U.S. restaurants while federal investigators worked to identify the cause of a deadly E. coli outbreak linked to the company's Quarter Pounder hamburgers. An Associated Press dispatch to The Globe reports that on Tuesday, McDonald's pulled Quarter Pounders from one-fifth of its U.S. locations due to the outbreak, which the U.S. Centers for Disease Control and Prevention reported had sickened at least 49 people across 10 states. One person has died and 10 others have been hospitalized, according to the CDC. A preliminary investigation by the U.S. Food and Drug Administration indicated that fresh slivered onions, which are served raw on Quarter Pounder hamburgers, were a likely source of the contamination. McDonald's announced that Quarter Pounders have been removed from menus in the affected states and in parts of other states as a precautionary measure. McDonald's has been in close contact with federal food safety regulators since late last week regarding a potential outbreak. The company's product popularity has made it challenging to pinpoint the contamination source.