Simple tweaks to the schedules of food safety inspectors could result in the discovery of hundreds of thousands of violations now being overlooked across the United States every year, according to new research about how scheduling affects worker behavior.

The potential result: Americans could avoid 19 million foodborne illnesses, nearly 51,000 hospitalizations and billions of dollars of related medical costs, according to “How Scheduling Can Bias Quality Assessment: Evidence from Food Safety Inspections.”

The paper was co-written by Maria Ibáñez, a doctoral student in the Technology and Operations Management Unit at Harvard Business School, and Mike Toffel, the Senator John Heinz Professor of Environmental Management at the school. They are experts in scheduling and in inspections, respectively.

Government health officers routinely drop in to inspect restaurants, grocery stores, schools and other food-handling establishments. Public health rules are strict, and business with serious violations must clean up quickly or risk being shut down.

Yet each year some 48 million Americans get sick, 128,000 are hospitalized and 3,000 die due to foodborne illnesses, according to the Centers for Disease Control and Prevention.

Previous research showed that the accuracy of third-party audits is affected by such factors as the inspector’s gender and work experience. Ibáñez and Toffel wanted to look at the effect of scheduling, because it’s relatively easy for organizations to fix those problems.

The researchers studied a sampling of data from Hazel Analytics, which gathers food safety inspections from local governments across the United States. The sample included information on 12,017 inspections by 86 inspectors over several years; the inspected establishments included 3,399 restaurants, grocers and schools in Alaska, Illinois and New Jersey.

In addition to studying quantitative data, Ibáñez spent several weeks accompanying food safety inspectors so she could see firsthand how seriously they took their jobs, how they made decisions and the challenges they faced.

“I’m impressed with inspectors,” she says. “They are the most dedicated people in the world.”

Still, the researchers analyzed the inspection records and found significant inconsistencies.

Underreporting violations causes health risks, they say in their report, and it unfairly provides some establishments with better inspection scores than they deserve. According to the data, inspectors found an average 2.4 violations per inspection. Thus, citing one fewer or one more violation can lead to a 42 percent decrease or increase from the average — and great potential for unfair assessments across the food industry, where establishments are judged on their safety records by both consumers and inspectors.

On average, inspectors cited fewer violations at each successive establishment inspected throughout the day, the researchers found.

They chalked this up to gradual workday fatigue; it takes effort to notice and document violations and communicate (and sometimes defend) them to an establishment’s personnel.

“The more inspections you have done earlier in the day, the more tired you’re going to be and the less energy you’re going to have to discover violations,” Ibáñez says.

They also found that when faced with working later than usual, inspectors worked more quickly and issued fewer citations.

“This seems to indicate that when inspectors work late, they are more prone to rush a bit and not be as meticulous,” Toffel says.

The level of scrutiny also depended on whatever had been found at the prior inspection that day. In short, finding more violations than usual at one place seemed to induce inspectors to exhibit more scrutiny at the subsequent place.

For example, say an inspector visits a McDonald’s restaurant and then a Whole Foods grocer. Suppose McDonald’s had two violations the last time it was inspected and this time has five or six. In that case, the inspector is likely to be particularly meticulous at the Whole Foods, reporting more violations than he or she might otherwise.

That behavior may be because inspectors put much effort into helping establishments learn the rules, create good habits and improve food safety practices.

“It can be frustrating when establishments neglect these safety practices, which increases the risk of consumers getting sick,” Ibáñez says. “When inspectors discover that a place has deteriorated a lot, they’re disappointed that their message isn’t getting through, and because it poses a dangerous situation for public health.”

On the other hand, finding fewer violations than usual at one site had no apparent effect on what the inspector uncovered at the subsequent establishment.

The public health stakes are high. The researchers estimate that tens of thousands of Americans could avoid food poisoning each year simply by reducing the number of establishments an inspector visits on a single day. Often, inspectors will cluster their schedule to do inspections two or three days each week, saving the other days for administrative duties. While this may save travel time and costs, it may also prevent inspectors from doing their jobs more effectively.

One possible remedy: Managers could impose a cap on the maximum number of inspections per day, and rearrange schedules to disperse inspections throughout the week — a maximum of one or two each day rather than three or four.

In addition, inspectors could plan early-in-the-day visits to the highest-risk facilities, such as elementary school cafeterias or assisted-living facilities, where residents are more vulnerable to the perils of foodborne illnesses than the general public.

Tweaking the inspectors’ schedules could lead to tens of thousands fewer hospital bills, the researchers concluded.

“Different scheduling regimes, new training, or better awareness could raise inspectors’ detection to the levels seen after they observe poor hygiene, which would reduce errors even more and result in more violations being detected, cited and corrected,” Ibáñez says.

The authors estimate that if the schedule effects that erode an inspector’s scrutiny were eliminated and the establishment spillover effects that increase scrutiny were amplified by 100 percent, inspectors would detect many violations now being overlooked.

“Scaled nationwide, this would result in 240,999 additional violations being cited annually, which would in turn yield 50,911 fewer foodborne illness-related hospitalizations and 19.01 million fewer foodborne illness cases per year, reducing annual foodborne illness costs by $14.20 billion to $30.91 billion,” the authors write.

While the study focuses on food safety inspections, it also offers broad lessons for anyone who has to manage or deal with inspections.

“One implication is that bias issues will arise, so take them into account as you look at the inspection reports as data,” Ibáñez says. “And another is that we should try to correct them. We should be mindful about the factors that may bias our decisions, and we should proactively change the system so that we naturally make better decisions.”

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