The USDA recently announced a recall of salads, packaged by Missa Bay, LLC, that were made from Oct. 14 through Oct. 16 because it could be contaminated by E. coli.
The U.S. Food and Drug Administration is investigating an E. coli outbreak that has sickened 40 people in more than a dozen states. The agency said its inquiry led investigators to farms in Salinas and that they were looking for the contamination source.
Romaine has been tied to repeated food poisoning outbreaks, including the one right before Thanksgiving last year. It's not clear exactly why romaine keeps sickening people, but food safety experts note the difficulty of eliminating risk for produce grown in open fields and eaten raw.
“It’s very, very disturbing. Very frustrating all around,” said Trevor Suslow, of the Produce Marketing Association.
The Associated Press contributed to this report.