As an outbreak of antibiotic-resistant Salmonella linked to ground beef unfolds in the Northeast, Rep. Chellie Pingree (D-ME) is asking the U.S. Department of Agriculture why it hasn’t found or revealed the source of contaminated meat.  

Pingree, who owns an organic farm in Maine and is an outspoken advocate for sustainable agriculture, asked USDA Wednesday if officials had made progress in pinpointing the source of contamination, according to The Portland Press Herald. So far, 16 people in seven states have been confirmed as part of the outbreak — seven people were hospitalized.

“We have asked them what is holding up (the investigation),” Pingree told the Portland Press Herald. “We get the same answer — that they are investigating the problem but are having a difficult time tracking down the sources of the meat.”

According to the local press report, the agency said last week that grocery chain Hannaford’s “limited records” were impeding the investigation and that the agency “is pursuing rule-making to address the concern.” If stores make their own ground beef, they are not currently required to keep track of which meat they use and where exactly it came from.

“That is currently voluntary,” Pingree said, according to the report. “This is a big system problem.”

Pingree is pressing USDA to get to the bottom of the outbreak.

“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.”

According to the Portland Press Herald, four Cumberland, ME residents were part of the outbreak. Two were hospitalized.

Pingree posted links relevant to the recall and outbreak updates on her congressional homepage for constituents looking for more information.