Health officials in the U.S. and Canada has told people to stop eating romaine lettuce because of a new E. coli outbreak.

The U.S. Food and Drug Administration said it is working with officials in Canada on the outbreak, which has sickened 32 people in 11 states and 18 people in the Canadian provinces of Ontario and Quebec.

FDA Commissioner Scott Gottlieb said the agency doesn’t have enough information to ask suppliers for a recall, but he suggested that supermarkets and restaurants should withdraw romaine until the source of the contamination can be identified. People are also being advised to throw out any romaine they have at home. No deaths have been reported. The last illness was reported on Oct. 31.

Washing contaminated lettuce won’t ensure that harmful germs are killed.