E. coli bacteria entered the public imagination in 1993, when Jack in the Box, a West Coast fast food chain, was the source of the most infamous food poisoning outbreak in modern American history. Beef patties contaminated with Escherichia coli O157—one of the deadliest types of E. coli pathogens—were found to have been sold at 73 of the restaurants across the country. More than 700 people were infected, 179 were left with permanent brain and kidney damage, and four children died. The last one to die was Darin Detwiler’s 17-month-old son, Riley.

Today, Detwiler is one of America’s leading food safety advocates, and a professor of food policy at Northeastern University. This week, he’ll be receiving Food Safety Magazine’s Distinguished Service Award—a bright spot in a career birthed by tragedy. It would be a more satisfying honor, though, if the United States weren’t currently dealing with yet another deadly outbreak of E. coli O157, he told me by phone last week. It’s as if my son were killed by a drunk driver, and I turn on the news and hear about another one on the road,” he said. “It’s like a knife in my back every time.”

On April 10, the Centers for Disease Control and Prevention warned against eating any romaine lettuce from anywhere in the country, fearing it might be contaminated with E. coli. At that point, 17 people had been reported ill, and six had been hospitalized. Three days later, the agency identified chopped bag lettuce from the Yuma, Arizona, region as the most likely source. Some companies issued voluntary recalls of their products, but the Food and Drug Administration refrained from issuing mandatory recalls, because they couldn’t find the exact source of contamination. The CDC’s warning remained in effect until June 28, when the agency said tainted lettuce from Yuma “should no longer be available.” In that update, the CDC said 210 people across 36 states were sickened by E. coli O157, and five people died, making it the worst outbreak in more than a decade.

The CDC’s green light to eat romaine again may have marked the end of the lettuce crisis in consumers’ minds, but the situation is far from over. The agency and the FDA are still investigating why and how a dangerous strand of E. coli wound up contaminating lettuce in Yuma. No single grower, harvester, processor, or distributor has been blamed, and investigators are still unsure whether contamination happened during the growing, washing, chopping, or bagging process. So far, the agencies have only released one finding: That the same E. coli strain found in sickened people across the country was also in Arizona’s canal water, which is used to irrigate crops.

This outbreak thus should not be seen only as a food poisoning outbreak, but a major water contamination crisis—the worst since Flint, Michigan. The agency’s finding also raises questions that Detwiler and other E. coli experts say more people should be asking, such as: How did deadly bacteria end up in crop water? And why does it keep happening in a country that’s supposed to have some of the strongest environmental protections in the world?


Escherichia coli is a naturally-occurring, but sometimes dangerous bacterium that lives in the intestines of animals, which is a polite way of saying it’s found in poop. The strain implicated in both the Jack in the Box and romaine outbreaks, O157, is called a “Shiga-toxin producing” strain, which can cause kidney failure and lead to death, particularly in vulnerable populations like children and the elderly.

O157 is among the most potent Shiga-toxin producing strains, according to University of North Carolina at Chapel Hill biologist Rachel Noble. “It takes only 100 cells of E. coli 0157 to make you sick,” she said, noting that it takes 5,000 to 10,000 cells of Salmonella bacteria to do the same. O157 is also most commonly found in the fecal matter of cattle, a fact Noble says is essential to figuring out the mystery of how it got into Arizona’s irrigation canals. “There are certain cows that we call ‘super-shedders,’ whose poop contains a ton of these organisms and we don’t know why,” she said. It’s therefore possible that manure from one of Yuma County’s many livestock operations ran off into the canals that fuel Arizona’s agricultural system.

An irrigation canal and valve outside Phoenix, Arizona.toolkit.climate.gov

If that material goes into an irrigation canal, it’s protected by all the things that would kill the bacteria,” Noble said. “It’s staying wet, it’s not exposed to sunlight.... If the water is moving along, being used through the ditches that run through the farms and then sprayed onto the lettuce, it becomes a problem.”

Government officials investigating the case aren’t yet ready to say that’s what happened. “More work needs to be done to determine just how and why this strain of E. coli O157 could have gotten into this body of water and how that led to contamination of romaine lettuce from multiple farms,” FDA Commissioner Scott Gottlieb said in a statement. The culprit could have been another animal’s fecal matter; it’s possible that humans relieved themselves in the canals. “More likely, it’s an open body of water, meaning animals can fly across it, drink from it, defecate in it,” Detwiler said.

But Detwiler thinks it’s less important where the poop came from than why the contaminated water was used on lettuce in the first place. “The liability issue comes down to, if you’re using a source of water like that, and you’re not monitoring and testing it. That’s where the problem lies,” he said. It is such a mystery as to who exactly is supposed to be monitoring the water used to clean and water crops.”

Up until very recently, Detwiler said, there were no federal regulations requiring growers to test the quality of water used on produce—those requirements were left up to state and local governments. But the public started questioning that practice in 2006, after yet another deadly outbreak of E. coli O157, on fresh spinach. Like the romaine outbreak, the source of contamination was water pollution, traced to cattle fields near the spinach fields. The 2006 outbreak resulted in at least 199 infections across 26 states, and three people died.

After that, the industry developed the Leafy Green Marketing Association, to start training growers on the best hand-washing and anti-contamination practices. And in 2011, President Barack Obama signed the Food Safety Modernization Act into law, compelling the FDA to develop regulations for water safety on produce. It took four years after that, however, for the FDA to enact the regulations—and they only require very large farms, rather than all farms, to sample and test the water used to grow and clean produce. Today, those regulations are still being phased in—meaning some farms have started monitoring programs, and others have not. No farms are required to report their data to the FDA until next year.

While the LGMA insists its member growers go above and beyond to ensure water safety regardless of regulations, Detwiler believes that’s not the case. “Do you know how many corporate officers have gone to prison for flouting health and safety rules that led to people’s deaths?” he asked. “Three—and the largest sentence ever handed down was three months.” That’s why Detwiler believes farmers don’t have enough incentive to ensure water safety. “If I’m a farm owner, I ask myself: Do I pay to have a third party lab to test these water samples on a regular basis for me to use this water? Or do I consider the small likelihood of someone being able to tie the problem back to me, and decide against it?”

Noble, the UNC biologist, is less convinced that farmers aren’t doing their part. “Most of the farms I’m aware of belong to [LGMA], and they’re interested in being proactive,” she said. The real problem, she said, is the effectiveness of most E. coli tests. “They’re only measuring for E. coli total, not the specific types of E. coli that can make you sick,” she said. “Because their data is total E. coli, they may not have known that there was a presence of E. coli O157 in the water.”

Whether the ultimate culprit winds up being inadequate E. coli tests, weak regulations, or industry bad actors, Detwiler said the romaine outbreak should be a wake-up call that not enough has been done to prevent deadly food-borne illness. “We haven’t learned our lessons,” he said. “It’s really sad that we’re at a time when we’ve just started implementing the Food Safety Modernization Act, there’s so much doubt cast upon science and regulations, because those are the things that are going to solve this problem.”

Once the FDA and CDC complete their investigation, Detwiler hopes the public will start demanding solutions to prevent future E. coli water contamination events. “Once you’re infected, there’s no do-over,” he said. “Believe me.”