By Michael J. Critelli | MakeUsWell Newsletter,
On July 20, 2026, The Wall Street Journal reported an embarrassing reversal by the Food and Drug Administration.
On July 18, 2026, the FDA had said that a sample of iceberg lettuce supplied by Taylor Farms from central Mexico had tested positive for Cyclospora, the microscopic parasite associated with a major outbreak of gastrointestinal illness. After reviewing the laboratory data, FDA concluded that the result did not represent “true amplification” and should be considered a false positive. As of July 19, 2026, the agency had no confirmed positive product samples.
That reversal might appear to demonstrate that our food-testing system is unreliable.
The more important lesson is different: no laboratory test, however sophisticated, can carry the entire burden of keeping food safe.
Polymerase Chain Reaction (PCR) testing is one of our most powerful detection tools. It searches for a specific genetic sequence and repeatedly copies or amplifies it until extremely small quantities can be detected. That sensitivity is precisely what makes PCR so valuable.
It also creates limitations. A PCR result can be affected by contamination, inhibitors in the food being tested or a signal that initially appears to be genuine amplification, but is not. Depending on the organism and method, PCR may also detect genetic material from an organism that is no longer alive or capable of causing infection. And detecting genetic material on one item does not, by itself, tell us where the contamination originated or whether it caused a particular outbreak.
That is why outbreak investigations depend on three different forms of evidence.
The first is epidemiology: What did the people who became ill have in common?
The second is traceability: Where did the suspected food come from, and where was it grown, processed, packed and distributed?
The third is laboratory testing: Can the organism be detected in food, water, equipment or environmental samples?
In the Taylor Farms investigation, the laboratory result was withdrawn, but the other evidence did not disappear. Among 190 cases for which Michigan investigators had detailed food-exposure information, 90% reported eating iceberg lettuce. FDA’s traceback investigation also converged on Taylor Farms as the supplier serving the Taco Bell locations where many of the affected people had eaten. The company therefore removed its central Mexico iceberg lettuce from the market, and the recall remained in effect while the investigation continued.
A recall can be prudent even when laboratory evidence is incomplete. Waiting for perfect proof can expose more people to harm.
The episode caused me to consider another seemingly straightforward solution: replacing human handling of produce with robots.
A robot does not come to work sick. It does not forget to wash its hands, become distracted or handle food differently at the end of a long shift. Automation could reduce risk in repetitive activities such as sorting, trimming, transferring and packing ready-to-eat produce.
But automation does not eliminate contamination. It changes the point at which contamination can occur. A robotic gripper, suction cup, blade, conveyor or collection bin becomes a food-contact surface. If that surface becomes contaminated, the machine can repeat the same contaminated movement hundreds of times with extraordinary consistency.
The robot has eliminated human variability, but may have automated cross-contamination.
Robotics therefore improves food safety only when the machinery is designed for sanitation, easily inspected, regularly cleaned and monitored as part of a larger preventive-control system. FDA’s produce safety framework addresses tools, equipment and buildings along with worker hygiene because both people and machines can transmit contamination.
More importantly, many produce-generated outbreaks begin long before either a person or robot touches the finished product. Potential sources include contaminated agricultural or wash water, untreated manure, animals, flooding, runoff, harvesting equipment and cross-contamination during processing.
Replacing human pickers does little to correct contaminated irrigation water. It does not keep wildlife out of a field, prevent runoff from neighboring land or guarantee that a wash system is operating properly.
The same systems perspective is necessary when we consider imported produce.
Imports supplied approximately 59% of the fresh fruit and 35% of the fresh vegetables available in the United States in 2023. Mexico accounted for 51% of the value of our fresh-fruit imports and 69% of our fresh-vegetable imports.
We cannot make that volume of food safe simply by testing selected shipments at the border. Contamination can be confined to one field, one water source, one packing line or one production lot. A clean sample does not prove that every item in a shipment is clean.
The U.S. system instead requires importers to evaluate foreign suppliers, approve them based on risk and performance, and conduct appropriate verification activities. In principle, food safety is supposed to be built into the supplier relationship rather than inspected into the product after it reaches the border.
But government oversight has significant limitations. The Government Accountability Office reported that FDA conducted an average of only 917 foreign food-facility inspections per year from fiscal years 2018 through 2023. FDA has not met its statutory domestic or foreign inspection targets since 2018.
That makes supplier transparency and accountability especially important. Regulators, retailers, restaurant chains and institutional buyers need to know the particular grower and packing facility, the importer’s verification history, the adequacy of agricultural-water and sanitation controls, the existence of FDA warning letters or import alerts, the traceability of each lot and the supplier’s record of responding to previous problems.
Country of origin alone tells us very little. A well-managed Mexican farm and packing operation may be safer than a poorly managed American one. But a distant or opaque supply chain can make verification, traceability and outbreak investigation more difficult. Local, controlled environment agriculture may be the promising option, but the level of controls of water and the other inputs for the food still matters.
The answer is not to distrust PCR testing, reject robotics or stop importing produce. It is to recognize the limitations of each safeguard.
A resilient food-safety system uses testing, epidemiology, traceability, hygienic automation, supplier verification and rapid recalls as overlapping protections. When one layer fails, as the initial laboratory finding apparently did in this case, the other layers must still protect the public.
The right question is not whether humans, robots or regulators can make food perfectly safe.
It is whether the entire system can prevent contamination when possible, detect it quickly when it occurs, contain it before it spreads and trace it back to its true source.