On January 14, 2022, FDA released a report on the investigation into the Summer 2021 outbreak of Salmonella Typhimurium associated with the consumption of packaged leafy greens. The investigation found that the outbreak was linked to leafy greens produced at a Controlled Environment Agriculture (CEA) indoor hydroponic operation.

In July and August of 2021, FDA, CDC, and state partners conducted an outbreak investigation into the leafy green outbreak. The investigation consisted of interviews with key personnel, observation of operations, the collection of samples, and environmental swabs throughout the operation. FDA was not able to identify the specific source of the contamination; however, the agency identified various practices that could result in contamination, such as contaminated pond water used to grow the leafy greens, growth media storage practices, water management practices, and general sanitation practices.

FDA notes that—while CEA, such as hydroponics, may differ in many ways from open field growing—many contamination risk factors are similar to those found in traditional agriculture. FDA has highlighted various requirements and recommendations for such operations, including:

• Understanding potential sources of contamination and implementing effective sanitation procedures and sampling plans

• Ensuring the implementation of appropriate preventative measures, including provisions of FDA’s Food Safety Modernization Act Produce Safety Rule and good agricultural practices

• Performing a root cause analysis when a pathogen is identified in the growing environment to determine how the contamination occurred and implement appropriate prevention measures

• Assessing and mitigating risks that may be associated with nearby land uses and may impact operations

FDA’s report is intended to prevent future outbreaks at similar operations by highlighting the factors determined to have contributed to the outbreak, which led to 31 illnesses across four states.