Protecting families from contaminated food and water
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Protecting families from contaminated food and water
Posted in E. coli,Our Blog on August 7, 2025
Researchers from Cornell University recently published a risk assessment of E. coli in leafy greens. The results are about what you would expect, given historical evidence. Readers of our Make Food Safe Blog likely recognize these topics from previous outbreak coverage.
So what did these researchers find?
Follow along as we break down their risk assessment of E. coli in leafy greens.
Based on the ongoing presence of foodborne outbreaks in the news and on your newsfeed, it probably doesn’t surprise you that the number of E. coli outbreaks, especially those involving leafy greens, have risen over the past few decades.
So much so that E. coli-contaminated romaine lettuce has emerged as the leading source of E. coli O157:H7 infections in the United States.
This particular strain of E. coli is especially dangerous, in that it produces a type of toxin (Shiga toxin) that can cause serious complications.
While cases were on the rise between 1996 and 2016, incidents picked up in 2015. Between 2015 and 2021, E. coli O157-H7 contaminated lettuce products were the source of seven outbreaks in the United States. Of which, six crossed into multiple states.
Overall, these outbreaks involved 4,274 laboratory-confirmed illnesses. This resulted in 766 hospitalizations and 11 deaths.
Leafy greens are, by definition, green. And leafy.
Spinach is considered a leafy green. As are lettuces. Romaine, butterhead, arugula, and even iceberg lettuce counts. So are collard greens like kale, mustard greens, and turnip greens. Even Bok choy and Swiss chard.
Microgreens and herbs like parsley, cilantro and basil are even considered leafy greens.
These produce items are especially vulnerable not only because they can pull germs into their leafy bodies from contaminated irrigation water. But also, because they are often consumed uncooked. Without sufficient heat treatment, germs can persist and cause human foodborne illness.
Several pre-harvest risk factors were identified. Most of which involved contaminated irrigation water and animal feces.
Both domestic and wild animals depositing feces in crop areas can contaminated leafy greens before they are harvested. Animal feces can contain harmful germs like E. coli, Salmonella, and other bad bugs.
Fencing can help segregate certain animals. But wild animals often find a way in. When it comes to birds, the only protection would involve a greenhouse. A solution for a smaller scale operation. Not realistic for a larger one.
Additionally, farmers often use biological soil amendments of animal origin. If not properly treated, this could contribute to contamination. Leading to the unintentional spread of foodborne illness.
The Cornell risk assessment of E. coli in leafy greens emphasized a significant risk associated with irrigation water.
Irrigation water can be contaminated through runoff from nearby animal operations, contamination with untreated surface water, and other methods of contamination.
Additional risk factors after the leafy greens are harvested involve not only the production process and distribution, but also consumer behaviors.
Maintaining harvesting equipment in the field and processing equipment at a processing facility can help reduce the growth and spread of E. coli in leafy greens.
Oftentimes, widespread multi-state outbreaks involve production facilities that take in raw product from multiple farms and package or process it further. Once equipment is contaminated, it can easily spread from one product to another if not effectively sanitized.
Production water used in processing facilities can also be a contributing factor. This water must be free of harmful germs. If it becomes contaminated, the number of products involved in a contamination event can be quite large. Resulting in huge product recalls, potential outbreaks, and a public health problem.
When it comes to risk assessment of E. coli in leafy greens, human behavior can be a wild card. Both at home and in the field. Proper handwashing and restroom facilities in the field can reduce the risk of contamination in the field. Ineffective washing once the consumer has the product in their possession can also impact potential foodborne infection.
The cold chain process of leafy greens was also mentioned in the Risk assessment of E. coli.
Maintaining refrigeration temperatures from harvesting, through processing, all the way to consumer purchase decreases the rate of bacterial growth. Maintaining an effective cold chain process, according to Cornell scientists, can reduce the risk of foodborne outbreaks.
We have talked a lot about the risks involved for E. coli in leafy greens farming and the production process. But what exactly is E. coli?
Escherichia coli, commonly called E. coli, causes a gastrointestinal illness with potentially life-threatening complications.
While anyone can become sick from consuming something contaminated with E. coli, some people are more likely to become infected if exposed to this germ, or experience serious illness if infected. The very young (under 5 years old), those over 65, and people with a compromised immune system are at the highest risk of becoming sick from E. coli in organic carrots in this outbreak.
The most common symptoms of E. coli infections include:
Call your doctor if you have diarrhea or vomiting that lasts for more than two days, have bloody poop or pee, fever higher than 102° F, signs of dehydration, or signs of hemolytic uremic syndrome.
Hemolytic uremic syndrome, or HUS, can be triggered by Shiga toxin-producing E. coli infections.
This complication occurs when the bacteria break down the red blood cells. These blood cell fragments clog the filtering activities in the kidney. Unable to perform properly, the kidney can fail. This can result in permanent health problems or even death.
Signs of HUS include:
About 5 to 10% of those infected with Shiga toxin-producing E. coli develop HUS.
People with HUS require hospitalization to monitor their kidneys and for other complications.
While most people recover within a few weeks with prompt medical care, others may suffer more permanent damage or even death from HUS related complications.
This risk assessment of E. coli in leafy greens explores the ways in which this popular, nutrient-rich food can become contaminated. Findings that can help growers, producers, and consumers alike to help prevent foodborne illness.
If you have become sick with E. coli from leafy greens (or any other food), The Lange Law Firm, PLLC has an E. coli Lawyer that can help you through this difficult process.
Foodborne illness can cause serious health problems and related financial burdens. An experienced E. coli Lawyer can help you understand your rights, gather important evidence, and represent you in court if necessary.
Call (833) 330-3663 or click here to fill out the online submission form and someone will get back with you right away.
By: Heather Van Tassell (contributing writer, non-lawyer)