Big Data vs. Bad Lettuce

The CDC estimates that food poisoning affects one in six Americans annually, totaling approximately 128,000 hospitalizations. For foodborne illness, 2018 has been a particularly virulent year: 237 people were infected with the cyclospora protozoa this summer when they ate Del Monte Vegetable Trays; 265 got sick from salmonella at the beginning of the year after eating contaminated chicken salad.

However, one of the most widespread incidents was a romaine lettuce E. coli outbreak that infected 218 people across the US. Walmart, Sam’s Club, and Kroger were forced to pull their romaine lettuce-containing products from the shelves in April when federal investigators discovered that the nationwide E. coli outbreak was from contaminated lettuce originating from the Yuma, Arizona region. Another pre-packaged salad company followed suit by recalling some 4 tons of their products – that’s roughly 8,000 pounds of salad.

Yuma, which promotes itself as the Winter Lettuce Capital of the World, is responsible for 90 percent of all leafy vegetables grown from November through March. All combined, the regional agriculture is worth approximately $2.5 billion to the local economy. Due to its proximity to fertilized soil, its difficulty in being effectively cleaned, and because it’s frequently consumed raw, lettuce is often responsible for foodborne illnesses such as E. coli. Months of investigation revealed that the Yuma outbreak was caused by irrigation of lettuce using contaminated water.

With a 21.5 percent market share in the US grocery industry, Walmart was quick to find a way to ensure that its customers would immediately know the origination of its produce. The company announced that it would collaborate with IBM using blockchain to reduce the time it takes to identify a source of outbreak. Walmart will require suppliers of leafy greens to join its blockchain within a year.

Blockchain is a digital ledger in which data is recorded on every computer in the blockchain network immediately. Any changes made to the data can been seen by everyone and falsifying data is extremely unlikely. While typical blockchains are open source, Walmart and IBM’s Food Trust blockchain is a “consortium” available only to Walmart’s supply chain, which includes hundreds of leafy green growers. Walmart will allow consumers access to some of the data in an effort to determine in seconds where their lettuce was sourced—instead of weeks or months passing before a consumer is made aware of a food recall.

Walmart began selling groceries in its Supercenters in 1988. By 2011, it had become the highest-ranked grocer in the US with $188.3 billion in sales. Kroger was a distant second with $76.2 billion. In the two years preceding the incident, Walmart was able to open an additional 94 stores, while Kroger and Safeway were forced to close 25.

Around the world, Walmart operates 11,695 stores. Because of its global influence, the company hopes that its blockchain requirement will shine a positive light on its suppliers and influence other stores to do the same. Already, the FDA has taken notice, announcing that food recalls will now include the specific names of retailers; this was not previously allowed for fear of influencing supplier-retailer relationships.