The Miami Herald reported Sunday that at first officials believed the source of contamination was a tomato, and then officials believed it was a jalapeno pepper, but now officials are not so sure what sickened 1,294 people since April.
Critics say the U.S Food and Drug Administration system for ensuring food safety is broken.
"The bottom line is this is not working," said Carl Nielsen, a 28-year veteran of the FDA and former director of import inspections. "There have to be radical changes."
"This is not a matter of throwing a few more million dollars at the problem and a 'tomatogate' wouldn't happen," he was quoted as saying.
Some have called for an overhaul of the nation's food safety laws.
"We need to move forward with much-needed modernization of our national food safety laws," said Rep. Adam Putnam, R-Fla. "These laws haven't really changed since the Eisenhower administration."