Researchers Identify Key Strategies to Enhance Romaine Safety

Public health concerns around romaine lettuce have prompted researchers at Cornell University to explore improved safety measures. A new study published on July 16, 2025, in Scientific Reports outlines effective strategies to mitigate the risks of E. coli contamination. Over the past two decades, the Centers for Disease Control and Prevention (CDC) has documented at least 42 foodborne illness outbreaks linked to romaine lettuce, highlighting the ongoing challenge this popular leafy green poses to consumer safety.

The study, co-authored by Renata Ivanek, a professor in the Department of Population Medicine and Diagnostic Sciences, and Martin Wiedmann, a food safety expert, emphasizes a multifaceted approach to safeguarding romaine. Their research focuses on interventions that address contamination both before and after harvest. “Interventions should concentrate on reducing produce contamination through irrigation water, ensuring that washing processes during processing effectively minimize bacterial presence, and enhancing temperature control throughout distribution,” said Wiedmann.

Ivanek noted the importance of industry collaboration in developing these strategies. “We aimed to provide a comprehensive overview of the system to account for various risk factors and their interactions,” she explained. This holistic analysis involved insights from an advisory council of industry leaders.

One major finding of the research is that a significant portion of contamination arises from untreated surface water used in overhead spray irrigation systems. To reduce this risk, the study suggests employing water treatments or transitioning to furrow or drip irrigation systems. While spray irrigation is beneficial for germination and cooling, it increases the chances of water contacting the leaves directly. “Drip or furrow irrigation methods significantly lower the risk of contamination,” Ivanek stated, although she acknowledged the potential cost implications for growers considering a switch.

The research also examined postharvest practices, particularly in processing facilities. Ece Bulut, a former research associate involved in the study, highlighted the complexities of washing romaine. “While washing processes are crucial, there are still gaps in understanding the optimal amounts of cleaning agents and the timing involved to ensure maximum effectiveness,” Bulut noted.

Additionally, maintaining appropriate cold storage temperatures throughout the supply chain is critical. Ivanek described a “perfect storm” scenario where contamination events coincide with improper temperature control during transport, leading to bacterial growth.

The push for increased consumption of fresh fruits and vegetables, led by Health and Human Services Secretary Robert F. Kennedy Jr. through his “Make America Healthy Again” initiative, underscores the urgency of enhancing food safety measures. Many leafy greens, including romaine, are consumed raw, making them particularly vulnerable to foodborne pathogens.

The comprehensive practices outlined in this study aim to guide decision-makers in refining food safety management practices across the supply chain. “The American food supply chain is notably safe compared to other countries,” Ivanek emphasized. “Our goal is to explore how we can make it even safer and identify areas where additional efforts are needed.”

The findings from this research are expected to influence future guidelines and practices within the industry, ultimately benefiting both producers and consumers. For more information, refer to the study by Ece Bulut et al., titled “Risk assessment of Escherichia coli O157:H7 along the farm-to-fork fresh-cut romaine lettuce supply chain,” in Scientific Reports.