The burrito chain (CMG) will shut its 1,900 U.S. restaurants on Monday for a meeting with employees to review a rapid overhaul of practices that it hopes will eliminate outbreaks of E. coli, Salmonella, and norovirus.

But there is no easy way to know whether the fast-food chain’s safety record is any better or worse than that of other major restaurant chain.

Food safety investigations in the U.S. begin–and often end–at the local level, and some states limit the disclosure of implicated restaurants, keeping diners in the dark.

Federal public health investigators get involved only when multi-state outbreaks are identified. A publicly available national database identifies tainted foods and pathogen culprits, but it would not help a consumer who wants to know whether one restaurant chain has a better safety record than another.

“There is not a surveillance system that exists nationally that answers that question,” said Matthew Wise, who leads the team investigating multi-state outbreaks at the U.S. Centers for Disease Control and Prevention.

Roughly 48 million people, one in six U.S. residents, are sickened by tainted food each year, and nearly 3,000 die.

Food safety advocates say more information would help. The development of a national database of safety scores broken out by chain could motivate restaurants to improve and maintain high standards, said Darin Detwiler, senior policy coordinator for STOP Foodborne Illness.

“We just want to know about the bad apples so we can avoid them,” said Detwiler, whose young son died in a 1993 Jack-in-the-Box E. coli outbreak that killed four children and sickened more than 700 people.

But Jeffrey Duchin, a Seattle public health official, said a national system for tracking restaurants by outbreaks could give consumers the wrong impression about where they can safely eat.

“Just looking at the ones that might have been reported with an outbreak that was detected would be a very biased sample,” Duchin said.

In Chipotle’s case, sales slid about 36% in January after falling by 14.6% in the fourth quarter. And the company said last week that a federal criminal probe linked to a food safety incident at a California restaurant has now widened into a national investigation.

Founder and co-Chief Executive Steve Ells boldly pledged in December to make Chipotle the safest place to eat. Asked later how the company would demonstrate it had met the goal, a spokesman said that executives were “less concerned about how we might rank that, and more concerned about reducing risk to a level near zero.”

National Chains, Local Focus

The first Chipotle outbreak hit diners of a Seattle restaurant in late July. Health officials learned of the E. coli illnesses in early August and linked them to the Chipotle outlet within days. But by that time, the alarm was over: The incubation period had passed, and no additional patients were expected, health officials said.

Local officials reported the outbreak to the state, which performed DNA testing to identify the E. coli strain. The Seattle cases only came to the CDC’s attention because the agency happened to have a team at the Seattle health department in August on another matter, Duchin said.

“It didn’t seem like anything remarkable at the time,” he said.

Last month, Seattle’s public health department began publishing more details about routine foodborne illness cases on its website in response to public demands for more information, spokesman James Apa said.

He said the information released includes the names of restaurants linked to routine outbreaks, a departure from the department’s previous practice of naming restaurants only when there is an identified, ongoing danger to the public. The change was under discussion before Chipotle’s problems.

In Minnesota, where Salmonella and E. coli outbreaks were linked to Chipotle outlets, officials don’t always publicly release the names of implicated restaurants, partly because of a belief that it might discourage operators from cooperating with investigations, said Kirk Smith of the Minnesota Department of Health.

In September, Minnesota officials decided to announce their investigation of Salmonella infections linked to Chipotle because, they said, there were a large number of cases and many affected people don’t seek healthcare or get tested.

National Surveillance

The CDC’s National Outbreak Reporting System gathers data on food and waterborne pathogens from states according to the type of pathogen and the setting of infection, such as hospital cafeterias, nursing homes, or restaurants. Names of establishments aren’t included or sought.

NORS is a database rather than an investigative tool, used by the agency to identify outbreak patterns.

Apart from NORS, the CDC participates in foodborne illness investigations when they involve outbreaks in multiple states, said Wise, who oversees those efforts. About 25 such outbreaks are identified each year, mostly involving food producers.

Even though multistate cases account for just 3% of all outbreaks, they are responsible for half of all food poisoning deaths. No deaths have been reported in the Chipotle outbreaks.