Introduction

We were delighted as our 12-year-old grandson ordered a Caesar salad when we were having dinner at a pizza identify. Vegetables! However, the dinner was December 22, 2019, shortly subsequently CDC and FDA issued yet another warning confronting eating romaine from Salinas, California. I asked the server where the romaine came from. He didn't know only went in the back to enquire. He returned and said, "Salinas."

Since 2017, vii outbreaks involving romaine lettuce have sickened hundreds and killed v. Those are the reported numbers. No ane knows how many other people got sick. In six outbreaks the lettuce came from California's Salinas Valley region; in the seventh from the Yuma, Arizona region, which includes California's Royal Valley.  Repeated FDA and CDC warnings against eating romaine have left consumers adrift in a body of water of disruptive announcements, advisories, and recalls. Is romaine safe to eat?

Between November and March, well-nigh all of the country's romaine, iceberg, reddish leaf, green leaf, arugula, broccoli, and cauliflower (collectively known as leafy greens) comes from the Yuma region. During the rest of the year, leafy greens are grown in the Salinas region. The 2 states produce 98 percent of the country'southward lettuce. Anyone who eats salad or likes lettuce on their Big Macs or tacos is personally impacted by how lettuce is grown and candy.

Nigh consumers will be surprised to acquire what happens to their lettuce earlier they bring it dwelling house from the supermarket.  Betwixt lettuce farms and the ultimate consumer is a remarkable arrangement of steps taken past farmers and processors to protect the safety of leafy greens. If an outbreak does occur, federal and state regulators utilize an elaborate network of laboratories to place the source of the contamination.

As a consequence, the chances of getting sick from eating leafy greens in America are minuscule. To put the risk in perspective, consider that California and Arizona farmers produce an estimated 130 million servings of leafy greens every day of the year.

Consumers should take comfort in knowing that farmers and processors, in response to the recent outbreaks, accept implemented fifty-fifty more stringent standards. That said, there are inherent risks in eating raw food that is grown outdoors. The system is not and never will exist perfect.

"I Wouldn't Wish This on My Worst Enemy"

On March 20, 2018, Louise Fraser, a 66-year-quondam woman from Flemington, New Jersey, ate a Fuji Apple Chicken Salad at a Panera Restaurant in Raritan, New Jersey. Over the next few days, she experienced severe tummy cramps, nausea, airsickness, headache, and a fever. When her diarrhea turned bloody, she went to the emergency room at Hunterdon Medical Center. On March 25th, the medical squad admitted her and began a battery of tests. Laboratory tests confirmed she was infected with Eastward. coli O157:H7, which caused hemolytic uremic syndrome, a condition that can lead to kidney failure and death. It took xiii days of medical supervision and three blood transfusions to save her life. She calls the infection "the worst feel of my life. I wouldn't wish this on my worst enemy."

Louise became ill from an outbreak of Eastward. coli O157:H7 traced to romaine grown in the Yuma region. The outbreak killed five people, hospitalized 96, and sickened 240 in 36 states, before ending in June 2018, making it the largest outbreak of this particularly nasty strain of E. coli since 2006.

Infectious Diseases and Nutrient

Guide books warn travelers to third-earth countries not to drink the water or eat raw vegetables for expert reason. Due to the lack of acceptable sanitation, the h2o is often contaminated with human or beast fecal thing, and farmers frequently use that water to grow vegetables.

Pathogens, including bacteria, fungi, and viruses, cause infectious diseases. E. coli O157:H7 almost often occurs in the intestinal tracts of farmyard animals, specially cattle, sheep, pigs, and poultry. The animals suffer no symptoms, simply they serve as carriers that shed leaner in their carrion, which can terminate up in the water supply. People can get sick from drinking contaminated h2o, merely virtually E. coli infections come up from eating food irrigated with the contaminated water.

Dozens of E. coli outbreaks associated with leafy greens have occurred since 1995. The worst one, in 2006, involved baby spinach that came from an organic farm in California's Salinas Valley. That outbreak prompted the California and Arizona lettuce industries, in 2007, to enter Leafy Greens Marketing Agreements (LGMAs), which crave members to comply with science-based guidelines for producing and harvesting leafy greens.

In 2011, Congress passed the Nutrient Safe Modernization Act (FSMA), which adopted the best practices of the LGMAs. The Human activity strengthened the food safety organization by broadening FDA's authorisation and requiring FDA to promulgate scientific discipline-based, minimum standards for the safe product and harvesting of fruits and vegetables.

Growing Lettuce: Nutrient-Safe Challenges

Lettuce farmers face food-safe challenges greater than other food producers. Pasteurizing, irradiating or cooking kills pathogens in most foods. But there is no "kill step" for lettuce, which is grown outdoors, not in a controlled environs like a factory or a greenhouse, and eaten raw. Paul Brierley, head of the Yuma Center of Excellence for Desert Agriculture, describes farmers' struggle against E. coli O157:H7 equally "fighting an invisible, tasteless, odorless enemy."

I first took students in my class, The Colorado River, on a field trip to Yuma in 2016. We met with a prominent farmer at his headquarters to learn most "food condom." If a flock of geese wing over the farmer'southward field, or a dog or deer wanders in, they may get out behind debris with Eastward.coli and other dangerous microbials. To monitor such intrusions, he keeps meticulous records of every occurrence and the response past engagement, time, and location. On his large briefing room table, stacks of binders chronicled food safety steps from preparing the fields each flavour through planting and harvesting.

Nutrient prophylactic, whether in Salinas or Yuma, starts with a pre-harvest inspection of fields and fertilizers.  Equally anyone with a backyard garden knows, manure helps things to grow. Just it's risky to utilize around vegetables. Before harvesting, food condom auditors (employed by shippers non growers) review a farmer'southward policies and records, conduct a visual inspection of fields for signs of fauna intrusion, and verify the practices are in place. The last step before harvesting involves taking samples from plants and sending them to a lab for testing. The usual practise is N60 or 60 samples in a 5-acre plot.

Harvesting crews work for packing companies and follow elaborate food safety practices. Outside each porta-potty is hand sanitizer. Pickers clothing gloves, masks and gowns, depending on whether lettuce is to be sold "naked" or candy. Workers cannot wear jewelry other than wedding bands or acquit anything in their upper pockets. Every picker's tools are numbered.

When crews harvest romaine for processing, they core and clean each head and identify them lesser side upwardly in boxes. They spray the boxes with water mixed with sodium hypochlorite and not-iodized salt to launder off latex, a naturally-occurring and harmless white-milky sap that oozes from the cuts. The spray helps to sanitize the cutting surface, close the plants' wounds, and prevent browning.

From Subcontract to Consumer

Harvested lettuce intended for processing is first sent to refrigerated warehouses, and vacuum cooled to 33-38 degrees F. At the processing plant, workers chop and shred the lettuce, which is sorted into unlike wash lines, for example, romaine in 1 and spinach in some other. It's usually triple-done in flumes, each time with fresh water. Automated controllers inject sanitizer into the flumes for the first and second washes. The sanitizer prevents leaner, such as E. coli O157:H7, that washes off a leafage from cross- contaminating other leaves during the washing cycle. The 3rd wash involves a potable water rinse.

The washed lettuce is dried in large stainless-steel barrels using centrifugal force.  Imagine a salad spinner that holds 300 pounds of lettuce. A machine and then lifts the barrels and dumps the lettuce into a hopper, which feeds a conveyor belt to a calibration, shaped like a cone with a bunch of buckets around it. A computer controls the buckets to measure the correct weight for each purse, depending on the customer'due south needs.

Workers back-flush the bags with nitrogen to control the amount of oxygen in the handbag. Processors employ modified temper packaging. I think of lettuce numberless at my local Safeway as "plastic numberless," merely processors regard them equally oxygen transmission rate (OTR) moving picture. 1 processor'south nutrient safety director (who asked me not to employ his name, so we'll call him John Doe) explains that "the OTR film is specific for each blazon of lettuce and allows for an substitution of gases between the within of the handbag and the outside." It allows just enough oxygen to induce the lettuce to go fallow. The lettuce remains in that land as information technology travels effectually the country until the bag is opened at a eating place or a home.

Each pocketbook is vacuum-sealed, run through a metal detector and manus-packed into boxes. At some processors, an inkjet printer stamps a label on every pocketbook and box. Each label, explains Doe, "has a unique code with the production appointment, plant code, pack line production shift, the stock-keeping-unit (SKU) lawmaking, and a timestamp down to the second." Workers place the boxes on pallets and load them onto refrigerated trucks.

Processors typically make clean the entire plant every day. "Sanitation for united states is the well-nigh of import part of the 24-hour interval," says Doe. "A crew of twenty cleans every chugalug, piece of cutting equipment, floors, drains, walls, everything. The process starts with a dry out pick-up so a rinse, and the application of chlorinated alkaline soap.  Workers foam and scrub the areas that need it, and finish upwardly with a final sanitizer, either peracetic acid or 4th ammonia. That'southward done every dark." On weekends, he explains, they shut the institute downwardly for "a deep clean period, from Sunday into Mon, when we practice preventative maintenance that we can't get washed during the week."

Shipper-processors sell to restaurant and grocery bondage and foodservice companies, such as Sysco, which delivers to schools and hospitals. In a matter of hours or days, lettuce arrives at grocery stores around the country. Ironically, consumers may be the weakest link in the produce nutrient safety system. What exercise you lot put on the seat in your grocery cart? Until recently, I put produce. At present I'm haunted by the image of the last customer'south dog, toddler, or purse. One time home, many consumers put lettuce into the sink or on a counter — two places loaded with bacteria.

A Mystery Fit for CSI

In early on April 2018, the New Jersey health section contacted CDC nearly a cluster of Due east. coli O157: H7 infections. Many of the sick people had eaten salads at restaurants before becoming ill. In subsequent days, according to Dr. Laura Gieraltowski, an epidemiologist who heads CDC's Foodborne Outbreak Response Squad, "illnesses with the same DNA fingerprint were uploaded to CDC'south PulseNet database — indicating a potential multistate outbreak."

PulseNet is a national network of 83 public wellness and food regulatory laboratories that submit samples of harmful bacteria from infected patients. FDA besides employs another network, GenomeTrakr, which sequences the genomes of foodborne pathogens and uploads data to a publicly-accessible database. The two systems function symbiotically, one generating data about patients, the other about nutrient.

Like a police detective looking at pins on a board in a murder investigation, Dr. Gieraltowski's team looks for points of convergence from clusters of disease with a common signal of exposure, such equally a restaurant. FDA'south network of specialists tries to figure out the origin of the contaminated food. Their approach is to motion backward from sick people through the food distribution organisation to the original supplier. This process, called a traceback, was exceedingly challenging in the April 2018 romaine outbreak.

Romaine is a perishable commodity with a short shelf life. By the time people become sick, physicians and clinics study their cases, laboratories test the specimens and fingerprint the pathogen, and wellness officials interview the sick people, the shelf life is over. Based on interviews with patients, clinical laboratory results, and Deoxyribonucleic acid fingerprinting, FDA announced on April xiii, 2018, that "the likely source" was farms in the Yuma growing region.

In June 2018, FDA investigators inspected farms, interviewed farmers and processors, and contacted cattle feeding operations and water districts. FDA teams were searching for the root crusade of the outbreak. CDC'southward National Antimicrobial Resistance Monitoring System (NARMS) laboratory used Whole Genome Sequencing (WGS) to determine that irrigation water from a Wellton-Mohawk Irrigation and Drainage District canal shared the aforementioned rare molecular fingerprint equally the O157:H7 that infected the sick people.  FDA found no other show of the presence of O157:H7.

To pinpoint precisely which farms and fields provided the romaine, investigators would demand samples to test. All the same, by the time the FDA team arrived in Yuma, the romaine season had ended, the farm equipment cleaned and stored for the adjacent season, and the processing plants closed downward. There was no romaine to examination. FDA did identify 1 farm that sent whole-head romaine to an Alaska prison where eight inmates got sick. In that case, the farm was the sole source supplier, simply it did not cause the nationwide outbreak.

On November 1, 2018, FDA'due south Ecology Assessment concluded the romaine came from the Yuma region. The traceback identified 36 fields on 23 farms that supplied romaine "that was potentially contaminated." (Emphasis added). Every bit seen on the Traceback Diagram (next page), multiple farms sent romaine to each processor, where the production became commingled as it was washed, dried, packed, and boxed. Distributors, in plough, received romaine from more than 1 processor. The commingling, FDA admitted, "made it incommunicable to definitively determine which farm or farms identified in the traceback supplied romaine lettuce contaminated with the E. coli O157:H7 outbreak strain." That'due south one reason why, on the Traceback Diagram, FDA redacted the names.

FDA's assessment of the Yuma outbreak concluded that "the most likely way" romaine became contaminated was from the Wellton-Mohawk irrigation canal water because that's the only identify FDA establish East. coli O157:H7. How did Due east. coli become into the water? FDA suspected the source was an adjacent Concentrated Animal Feeding Operation (CAFO). The 5 Rivers Cattle, LLC feedyard in Wellton, Arizona, virtually 30 miles east of Yuma, can house more than than 100,000 head of cattle at a time.

FDA Traceback Diagram

I asked Bill Marler, a leading nutrient safety attorney, what he thinks caused the outbreak. Marler said the answer is obvious if you await at an aerial photo of the CAFO shut to the canal. "It doesn't take a rocket scientist to effigy out the probable source of O157 in the Yuma valley. It's cow shit." He is inappreciably alone in reaching this conclusion, though several people expressed their views off-the-record. Manure is a vexing problem for feedlots: each steer can produce 65 pounds per twenty-four hours, about of which is h2o.

Nagging doubts remain. For case, if canal water contaminated romaine, why did it not also contaminate baby leaf, spinach or bound mix, which are irrigated with the same water. If culvert water did not contaminate romaine leaves, is at that place some other explanation? FDA ruled out wild animals because O157:H7 is an antibiotic-resistant strain, suggesting it came from the scat of domestic animals, who were inoculated or given feed with antibiotics in it.

FDA inspectors sampled soil, wild and domesticated animal scat, biological fertilizers, surface and subsurface water, irrigation water from the Colorado River, and sediment from irrigation canals. In the cease, only three samples from the Wellton-Mohawk canal tested positive.

FDA also considered unusual weather patterns, including a hard freeze in February 2018 and stiff winds in March 2018. The cold temperatures blistered romaine leaves, making the crop more than susceptible to microbial contagion. High winds perchance carried contaminated soil particles and romaine — with creased, upturned leaves — may be more vulnerable to trapping airborne particles. Aerial applications of pesticides could have caused the problem if the water used to dilute the chemicals was contaminated. Peradventure a pesticide applicator drew water from the irrigation canal and so sprayed fields with contaminated h2o.

FDA acknowledged these other theories merely found no evidence to support them. The bottom line is that Wellton-Mohawk culvert h2o tested positive for E. coli O157:H7, which unremarkably occurs in cattle, and a giant feedlot was located next to that canal. The rest is inference.

Outbreaks in November and Dec 2019 caused by lettuce from Salinas spawned another plausible caption for the root cause, which focuses on timing. Six of the seven outbreaks since 2017 occurred toward the stop of the romaine flavour, whether in California or Arizona. When farmers rotate their crops, they oftentimes spread manure or composting materials in advance of planting — at a time when romaine is yet in the footing in neighboring farms. Mayhap wind or water spread Eastward. coli to the romaine fields.

A May 2020 FDA report on the November and December 2019 outbreaks ended that "a potential contributing factor [was] the proximity of cattle to the produce fields." The written report was not referring to a massive CAFO but cattle grazing on public land on nearby hills — as far away as two miles from the romaine fields. This should send a shudder through ranchers and farmers across the Due west because the bucolic image of cattle grazing on a hillside is often visible from low-lying farms.

"We Don't Know Exactly What to Fix."

In April 2018, before FDA investigators arrived in Yuma, the leafy greens industry established task forces to examine current practices and propose reforms. For case, harvesters now clean and sanitize the equipment daily. Farmers and processors changed many practices, hoping that one or a combination would have an affect. "But we only don't know," explained John Doe, the food prophylactic managing director. "And that's the actually frustrating thing for everybody. Our customers and really the entire U.S. public wants united states of america to fix it, fix it, set it. And we don't know exactly what to fix." All the same, one processor decided to stop buying from farms inside a mile of a CAFO. That processor likewise inverse its pre-harvest sampling methodology from sampling v-acre plots to sampling every acre.

In 2019, the Leafy Greens Agreements began to require growers to care for all surface water used within 21 days of harvest. (Before that, sunlight exposes vegetables to plenty UV radiations to kill virtually all dangerous pathogens.) Dr. Jennifer McEntire, vice president of food safety for United Fresh Produce, a trade association, describes this alter as "a fundamental shift" from testing h2o on an annual basis to "proactively treating h2o during the period closest to harvest."

"Food Traceability @ the Speed of Idea"

On Nov 1, 2018, FDA then-Commissioner Scott Gottlieb called for the industry to standardize record-keeping and to utilise labels or other tools to meliorate traceability.  Nutrient safety records on many farms are hand-written notes.  Some numberless and boxes take labels that identify the variety, grower, field, and harvest date; others don't. The lack of a compatible standard creates problems for fast traceback. United Fresh Produce's Jennifer McEntire supports improved labels. "If nosotros have truthful traceability, we could

pinpoint exactly what the problematic product was, who produced it, and when. Nosotros wouldn't need a broad informational." Labels on romaine now include the growing region (Salinas or Yuma), which enabled FDA in November 2019 to limit its consumer warning to romaine from Salinas.

In December 2018, Frank Yiannas, a renowned food safety expert at Walmart, became FDA Deputy Commissioner for Food Policy and Response. At Walmart, Yiannas used blockchain, the all-time-known type of digital ledger engineering science, to track mangos from ii farms in Mexico to two stores in the United States. In a pilot project, each participant in the supply chain put data on the blockchain, which linked the blocks of data and reduced traceback time to ii.2 seconds. Existent-time traceability is the holy grail to Yiannas, who refers to it as "food traceability @ the speed of thought."

In April 2019, Yiannas and FDA Acting Commissioner, Ned Sharpless, Thou.D., announced that FDA would enter a New Era of Smarter Food Safety, anchored by moving from largely newspaper-based data to a digital arrangement, such every bit FedEx, Uber, and Amazon use to track the movement of trucks, ride sharing and commitment of packaged goods. The new era arrived in July 2020 with FDA's Blueprint for Smarter Food Rubber, which will encourage and incentivize the leafy greens industry to prefer tech-enabled traceability measures. The labels on bags and boxes of lettuce may presently accept information stored on the cloud or blockchain.

But labels tin can amend traceability simply if data gets saved. No thing how remarkable digital ledger technology is, it will promote traceability just if the shipping/receiving clerk at a restaurant or a supermarket scans the labels when the boxes make it. Yuma farmer John Boelts notes that traceability breaks downwards in "the final mile to the consumer," when supermarket workers or habitation cooks throw away the bags and boxes. At a public meeting on the New Era that FDA hosted in October 2019, Yiannas acknowledged this problem: "What matters most is what people do." The beliefs of everyone in the nutrient industry, from farmers to servers, volition ultimately determine the safety of our nutrient.

In September 2020, FDA announced a proposed rule regulating recordkeeping that would require the leafy greens industry to go along records with Disquisitional Tracking Events and Cardinal Data Elements. Prompt traceability requires 3 conditions: compatible labels, interoperable data collection and storage, and unanimous participation by growers, processors, shippers, and buyers. Although this dominion has many exemptions, information technology would go a long style toward creating those atmospheric condition.

Uniform labels and effective digital storage could dramatically reduce traceback times. Better data will not prevent the initial consumers of contaminated produce from becoming ill, simply it could limit the scale of an outbreak by quickly determining the source of the contamination. Other current inquiry is directed at prevention past achieving real-time detection of pathogens before the lettuce ever enters the food chain. Paul Brierley, caput of the Yuma Center of Excellence for Desert Agriculture, has a enquiry projection involving biosensors, which would enable farmers to detect pathogens in water or in the processing plant. Brierley concedes: "We accept a long way to go."

In Oct and November 2020, FDA announced an investigation of three new outbreaks of E. coliO157:H7. Its traceback investigations were unable to determine a common source of the outbreaks.

What Should Consumers Practise?

In the meantime, consumers face difficult choices. They certainly should not stop eating romaine and other leafy greens. Nutritionists hold that we should eat more fruit and vegetables.

Consumers may choose to wash all lettuce, even the bagged and boxed mixes. Despite the elaborate precautions taken past processors, contaminated romaine made its way into the distribution organization. In November 2018, FDA warned that washing "may reduce only will non eliminate [E. coli O157:H7] from romaine lettuce." Despite this alert, I don't program to commencement washing lettuce that has already been triple done.

Consumers have other choices, including buying organic produce. But it is worth remembering that the 2006 Due east. coli O157:H7 outbreak involved spinach from an organic farm. Other consumers may prefer to purchase greenhouse-grown lettuce, which has not been implicated in recent outbreaks. Simply lettuce grown indoors is a niche market place, not one capable of producing tens of millions of servings a day. Still others may want to buy from farmers markets. Simply it is unclear whether that lettuce is safer than processed lettuce from California or Arizona. Plus, few farmers markets are open from belatedly fall through winter, which is the Yuma season. If y'all desire lettuce during those five months, it's going to come from Yuma.

When bad things happen, Americans wait that someone or something is to blame. Nosotros want everything to be perfect, whether it's a medical procedure, a machine repair, or the nutrient we consume. All the same, no corporeality of testing and treating will completely eliminate the take a chance of getting ill from eating raw something that is grown outdoors.