In the largest US outbreak of Escherichia coli (E. coli) since 2006, five people have died and almost 200 people fell ill, with many requiring hospitalisation, after eating contaminated, pre-cut packaged lettuce.
The Centers for Disease Control and Preventions (CDC) linked the March outbreak to romaine lettuce from Arizona’s Yuma region, which are no longer being sold since the growing season there has finished. However, the Food and Drug Administration (FDA) has admitted it may never know the precise cause of the contamination. This is due to a complex supply chain involving dozens of farms, processors and distributors for pre-cut lettuce.
According to the FDA tracing the outbreak is a labour-intensive task requiring the collection and evaluation of thousands of records to try and pinpoint how the contaminated lettuce moved through the food supply chain to grocery stores and restaurants to affect consumers across 35 states.
While Yuma-sourced lettuce is off the menu for the time being, without knowing whether there is an environmental problem affecting the region, and therefore applying a remedy – it will be difficult to trust the product in the future.
Pre-cut, washed and packaged salads have become increasingly popular for time-poor consumers, but apart from traceability issues, the product itself amplifies contaminations and disease risk. Contamination can occur when lettuce is harvested, or from animals or water in fields. During processing bacteria living among leafy greens has a moist environment that provides ideal conditions to grow in the bag as it is shipped across the country.
The lettuce is then eaten raw, providing no opportunity to kill off pathogens. In fact, a 2013 CDC analysis of food poisoning cases between 1998 and 2008 found that leafy vegetables including salads caused almost a quarter of all food poisonings. While the vast majority of salad is safe to eat, leafy vegetables do cause more sickness than any other food product, including what many consumers would consider the usual suspects, like dairy and poultry.
It seems incredible that in 2018, US authorities can’t trace the source of such serious food contamination. However, it seems packaged and pre-prepared products, with their longer and more complex supply chains could be a key source of risk, as well as making traceability challenging.
Is it time to consider whether the convenience of pre-processed and packaged salad is really worth the additional risk? The wider lesson seems to be – wash your salad!