The U.S. Department of Agriculture should explain to the public why it hasn’t been able to identify the source of contaminated meat sold by Hannaford Supermarkets over two months this fall, said U.S. Rep. Chellie Pingree.

Almost a week after Hannaford issued a recall of the ground beef, the USDA would not say Wednesday whether it has made progress toward determining the source of the contamination that led to the outbreak of a rare form of salmonella.

“We have asked them what is holding up (the investigation),” said Pingree, D-1st District, a member of the House Agriculture Committee. “We get the same answer — that they are investigating the problem but are having a difficult time tracking down the sources of the meat.”

Scarborough-based Hannaford, which has stores in five states, issued the recall last Thursday of ground beef with sell-by dates of Dec. 17 or earlier.

In all, 16 people from seven states — including four from Maine — had reported becoming ill from Oct. 8 to Dec. 3 and had tested positive for the salmonella strain, the U.S. Centers for Disease Control and Prevention said Tuesday. Of those people, 10 said they ate ground beef from Hannaford stores, and seven were hospitalized.

Last week, the agency said Hannaford’s “limited records” were impeding the investigation and that the USDA “is pursuing rule-making to address the concern.”

Experts say Hannaford’s case is just the latest example of a foodborne illness investigation that has been hindered by less-than-ideal record-keeping practices.

“It happens all the time,” said Bill Marler, a food safety lawyer from Seattle, Wash.

The problem is that stores often mix meat from different sources into a batch of ground beef, and they’re not required to record what meat was used. The beef is ground in the stores.

“That is currently voluntary,” Pingree said. “This is a big system problem.”

Sometimes combing through records can result in identifying a source of the contamination, but not always, said Marler.

“You might simply not be able to do it,” he said.

USDA spokesman Neil Gaffney has not responded to repeated requests from The Portland Press Herald for information about what is lacking in Hannaford’s records or what new rules the agency is considering.

Pingree criticized the agency Wednesday for not telling the public more about the weak record-keeping requirements that make it difficult to quickly track down the source of contaminated meat.

“It is good for the USDA to give more information to the public,” Pingree said. “A case like this helps the public understand why we need more record-keeping and tracking.”

Hannaford spokesman Michael Norton, who has said the grocery chain complies with industry record-keeping standards, wouldn’t speculate about what information would make its records more complete.

Pingree said the chain is not to blame for the difficulty of the investigation.

“They have been doing everything they are required to do,” she said. Pingree said a “fault in our system” is the real hurdle.

Pingree said the USDA is working on new rules that could be in place as soon as next year and would require stores to keep track “of every piece of beef that goes into a package of ground beef.”

It would help if more people were aware of the problem, she said, which is why the USDA should be making more of an example of the Hannaford investigation.

“If the USDA was more open with people about the fault in our system, we would be more likely to fix the system and have the political will to do it,” she said.

Hannaford will give refunds for any ground beef within the recall’s scope, regardless of whether it’s still in its package, Norton said. The recall covers the Hannaford, Taste of Inspirations and Nature’s Place labels.

Norton said last week that Hannaford supplies groceries wholesale to about 30 independent stores, but he did not know how many of those stores buy ground beef from Hannaford.

The Hannaford stores linked to illnesses are in Maine, New York, New Hampshire and Vermont, according to the USDA. The first case in Maine was reported on Oct. 22, Dr. Stephen Sears, state epidemiologist, said last week.

The four Maine residents who were infected are from Cumberland, York, Androscoggin and Waldo counties, said Sears. He said one of them was hospitalized for four days and another was hospitalized for two days.

Common symptoms of salmonella infection include diarrhea, abdominal cramps and fever within 12 to 72 hours of eating contaminated food, according to the USDA. Other symptoms are chills, headache, nausea and vomiting. They can last for as long as a week.

Salmonella infection can be life-threatening, especially for people with weakened immune systems, including infants, the elderly and people who have HIV or are undergoing chemotherapy.

The USDA urges people to eat ground beef only if it’s cooked to a temperature of 160 degrees, confirmed with a food thermometer.

Staff Writer Leslie Bridgers can be contacted at: 791-6364 or at

lbridgers@pressherald.com