Summer is officially underway! Now is the time to enjoy fresh salads loaded with fruits and veggies. And, despite the recent outbreak, we now know the romaine available today is safe so there’s no need to be deterred from enjoying your favorite summer salads.

Pinpointing the source of a foodborne illness outbreak

The FDA is charged with determining how, when and why an outbreak occurred. Collaborating with the CDC, state and local regulatory agents, public health officials, and agriculture departments, the investigative process examines documentation from growers, harvesters, processors and distributors.

The collected data is then shared with the FDA’s Coordinated Outbreak Response and Evaluation (CORE) Network. A CORE response team is assigned to find out the exact cause, control the spread, and ultimately stop the outbreak. The CORE team tracks down the source of the contaminated food and its movement through the supply chain. The data is then compared to what is known about the illnesses to ensure the investigation is on the right track.

Electronic labeling helps the process

About a decade ago, produce industry members started the Produce Traceability Initiative (PTI) and invested heavily in PTI technologies so they could trace harvested products back to the field. Currently, about 60% of the produce industry uses labeling through the initiative.

When fruits and vegetables are harvested in the field, cartons holding the fresh produce are typically labeled with an electronic-coded sticker containing detailed information about the harvest date and time, the grower, farm and location, as well as information about the harvesting company and crew members who performed the harvesting.

While PTI is extremely helpful to trace a product back to its farm source, every other entity along the supply chain to the consumer must also maintain the integrity of product tracing information. One example of this is Supplier X that sells food to restaurants: it may buy lettuce from Companies A, B, and C, and then repackage it into different cartons. These newly repackaged cartons, now containing a variety of lettuces, have new labels that only include data about the product as it was handled at Supplier X and not information from Companies A, B, and C.

Another example is the grocery stores. Have you ever walked behind a restaurant or grocery store and seen a pile of empty boxes that once held food? After the produce is removed, the box with the label telling the restaurant or grocery store where the product came from, when it was picked, who picked it, etc. needs to be properly scanned into the store or restaurant’s system.

The FDA detective work begins….

So, what does the FDA do when they come to a dead-end, like a break in the electronic chain of information? They must sift through the company’s paper records and interview company personnel to piece together as much supply chain information as possible. This elusive detective work takes days – sometimes weeks.

As we know, it is so easy to purchase a bag of pre-mixed vegetables or salad straight from the grocery store. Well, as we saw with romaine, many of these items are mixed together from different suppliers. So you can see how the supply chain gets complicated! Here’s an example of a supply chain that the FDA may encounter during an investigation:

Investigating the supply chain gets complicated! There can be many companies and farms involved.

As you can see, the investigation quickly broadens to include multiple potential paths. Because Company B mixes lettuce from three sources, the FDA must assume that the contaminated lettuce came from any one of Companies C, D, and E. In reality, the contaminated product may only have come from Company C, but the FDA has no way of knowing this since the lettuce from all three companies is mixed together.

To further add to the complexity, Companies C, D, and E each have four farms and each farm has 1,500 acres of lettuce which are divided into multiple lots. If Company B retains the information from the lettuces from their three suppliers, then the FDA may be able to narrow the potential farm sources from 12 to 4, but too often this information is lost when the carton is thrown away.

Environmental Assessments

After tracing the contaminated product as close to its origin as possible, the FDA’s CORE team visits the location where contamination is thought to have occurred. If the location is a farm(s), they conduct what is referred to as an “environmental assessment”, noting potential hazards and taking samples of water, soil, and other agricultural inputs. They also assess the surrounding areas and collect samples related to wildlife and domestic animals (e.g., feces, water troughs, bedding) known to carry the pathogen.

If the contamination is believed to have happened at a facility, they visit the facilities involved and swab equipment, walls, floors, drains, etc. In addition to sampling, CORE members interview personnel who work at the farm or facility, asking questions about their practices and observations, as well as anything out of the ordinary that may have happened before the outbreak.

Race against the clock

When investigating foodborne illness outbreaks, the CORE teams are working against the clock, as weather and other environmental conditions may become unfavorable to pathogen survival and the bug may begin to die off. Even in facilities, conditions change (i.e., equipment is cleaned and sanitized), and the responsible pathogen may no longer be found. Because of this, there is a real possibility we may never know what caused the E. coli outbreak in romaine. However, that does not mean the work will not continue. Industry members join forces with government investigators – meeting with FDA officials and CORE members to discuss their practices, growing conditions, and potential risk factors.

You begin to see how much ground investigators need to cover in order to determine where and how the lettuce became contaminated.  But the FDA CORE teams work tirelessly to ensure that Americans are eating safe produce. While it is a tough job with many challenges, the CORE teams have many tools in their toolbox to help them solve outbreak causes

Farmers and growers continually work on food safety protocols

Farmers and growers need to know how the contamination happened so they can do everything possible to keep it from happening again. In the case of the romaine outbreak, the leafy greens industry has formed a task force and members are actively researching and gathering information as well as re-evaluating their food safety practices. In addition, the produce industry trade associations are working on solutions that will enable the industry to address gaps in traceability to more efficiently find the source of problems when they occur.

Special thanks to Dirt-to-Dinner contributors Susan Leaman and Diane Wetherington of iFoods Decision Sciences.