US – In a study conducted by researchers from Ohio State University, the true toll of leafy greens on public health and economics in the United States has been laid bare.

Using sophisticated models, the study unveiled that leafy greens account for 9.18 percent of all known foodborne illnesses caused by pathogens in the U.S annually.

Such infections incur a hefty economic burden, reaching a colossal USD 5.278 billion. The culprits behind most of these illnesses and costs are norovirus, non-O157 and O157:H7 Shiga toxin-producing Escherichia coli (STEC), Campylobacter, and nontyphoidal Salmonella.

Leafy greens such as romaine, iceberg, and other lettuce varieties emerge as the prime suspects, responsible for 60.8 percent of outbreaks. These varieties contribute to 75.7 percent of foodborne illnesses tied to leafy greens, as well as a formidable 70 percent of associated costs.

Among the leafy greens subtypes, romaine lettuce stands out as a notable contributor to foodborne illness. 19.8 percent of STEC O157:H7 illnesses can be attributed to romaine lettuce, resulting in approximately 12,496 cases of illness annually, with a hefty economic toll of USD 324.64 million.

Modeling the risks

The study underscores the critical role of modeling in assessing foodborne illness burdens accurately. By incorporating three distinct attribution models, the researchers navigate the complexities of singular versus complex food outbreaks, offering valuable insights into the nature of risk assessment.

Each model brings its unique perspective, informing the multifaceted landscape of foodborne illness attribution.

Despite the advancements in modeling techniques, the authors caution against viewing any attribution model as flawless. Each model presents its own set of strengths and limitations, and the choice of model can significantly impact the estimated burden of foodborne illnesses.

The study emphasizes the need for continued refinement and collaboration in the field of food safety research to enhance the accuracy of such estimations.

Initiatives to ensure safety

Between 2014 and 2021, the CDC documented a total of 78 foodborne disease outbreaks associated with leafy greens, primarily lettuce. Notably, growers of leafy greens, particularly those producing Romaine lettuce, have faced outbreaks of E. coli O157:H7 on eight occasions since 2017.

In response to these outbreaks, both the private Leafy Green Marketing Agreement (LGMA) and the public Food and Drug Administration (FDA) took proactive measures last year to address the issue.

The California LGMA initiated a “Romaine Test & Learn” study, spanning two years, aimed at enhancing food safety. This study involves growers providing their pathogen test data for analysis by LGMA.

Additionally, since March 2020, the FDA, along with public and private sector partners, has been actively involved in improving the safety of leafy greens through the implementation of the Leafy Greens STEC Action Plan (LGAP).

This comprehensive plan includes prioritized inspections, focused sampling, stakeholder engagement, data sharing, root cause investigations, and advancements in detection and prevention science.

As part of these efforts, the FDA proposed a rule for the agricultural water provisions of the Produce Safety Rule, applicable to covered produce excluding sprouts.

Furthermore, the FDA has developed and launched an online tool to help growers assess potential risks associated with their water sources and identify management options to mitigate those risks.

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