The number of people sick from salmonella-tainted tomatoes jumped to 228 in 23 states Thursday as the government learned of five dozen previously unknown cases and said it is possible the food poisoning contributed to a cancer patient’s death.

Twenty-five people have been hospitalized as a result of the U.S. outbreak, which has been linked to raw plum, Roma and round tomatoes.

The Food and Drug Administration has not pinpointed the source of the outbreak. With the latest known illness striking on June 1, officials also are not sure if all the tainted tomatoes are off the market.

The FDA’s food safety chief, Dr. David Acheson, said,

"As long as we are continuing to see new cases come on board, it is a concern that there are still contaminated tomatoes out there."

The FDA is directing consumers to its Web site — http://www.fda.gov — for updated lists of the safe regions.

Also safe are grape tomatoes, cherry tomatoes and tomatoes sold with the vine still attached. That is not because there is anything biologically safer about those with a vine but because the sick have assured investigators that is not the kind of tomato they ate.

What if you did not go to the store armed with a list, or the store or restaurant manager cannot assure that any plum, Roma or round tomatoes came from safe regions?

"If you don’t know, don’t take the risk," Acheson said.

Cooking also kills salmonella, but the FDA is not formally advising people to cook suspect tomatoes for fear they will not get them heated thoroughly.

(The possibility also exists for cross-contamination during preparation — dp).

Meanwhile, export-quality tomatoes labeled "Ready to Eat" in English flooded Mexico City markets on Thursday after a salmonella scare in the U.S. stopped them from crossing the border.

Associated Press reports that most consumers do not even know about the U.S. salmonella scare. And those who do, rarely care. Mexicans are accustomed to washing all produce because the vegetables sold on the national market are not held to the same standards as those certified for export.

Sergio Martinez, a 40-year-old bricklayer, said, "What the U.S. doesn’t want is what we see here. They always send the best stuff over there, from avocados to tequila. What ends up here is second-rate. Almost all vegetables are contaminated with something because they water them with sewer water and put on a lot of chemicals."

Agriculture Secretary Alberto Cardenas told Televisa network Thursday, "The Mexican tomato is safer and cleaner than ever."

Even U.S. officials agree that certified Mexican exporters are among the safest in the world. Their fields are irrigated with fresh water, and their packing plants are staffed by workers covered head-to-toe in sterile clothing. Inspectors monitor the process at every step.