Early last month, the U.S. Food & Drug Administration (FDA) announced a recall of tomatoes distributed to Georgia, North Carolina, and South Carolina due to potential contamination with Salmonella, a dangerous pathogen that can cause serious illness, and sometimes, death in certain members of the population.
On Wednesday, May 28, this recall was upgraded by the FDA to its highest ranking, Class I, meaning that “there is a reasonable probability that the use of, or exposure to a violative product will cause serious adverse health consequences or death.”
Tomatoes rank among the most common produce items linked to Salmonella outbreaks in the United States, with contamination risks arising from both biological characteristics and agricultural practices. Research indicates several factors contribute to this susceptibility.
Biological Entry Points
The tomato’s surface structure facilitates pathogen attachment. Microscopic cracks, bruises, or the porous stem scar tissue provide entry routes for Salmonella. Once internalized, bacteria can migrate into the fruit pulp. Studies show Salmonella survives more effectively on tomato surfaces (82% of contaminated samples) and stem scars (73%) than in pulp (55%). Even minor damage during harvesting or packing can exacerbate this risk.
Favorable Internal Environment
Contrary to assumptions that acidic fruits inhibit pathogens, tomatoes permit Salmonella growth under certain conditions. Research demonstrates that Salmonella proliferates in water-congested tissues of green tomatoes and thrives particularly well in red ripe tomatoes, which may offer more nutrients or moisture. Strains like Montevideo persist for up to 49 days post-inoculation, surviving from flowering through fruit development.
Agricultural and Handling Factors
Pre-harvest irrigation practices indirectly influence susceptibility. While irrigation levels themselves showed no direct correlation, tomatoes grown in sunny, dry seasons exhibited higher post-harvest pathogen proliferation. Contamination can originate from multiple sources:
- Water: Irrigation with contaminated water introduces bacteria.
- Field Conditions: Pathogens from soil, manure, or wildlife can transfer during harvesting.
- Post-harvest Handling: Cutting, washing, or packing may spread bacteria, especially if equipment or surfaces are contaminated. UV irradiation, a common post-harvest treatment, was found to promote Salmonella growth in some cases.
Challenges in Decontamination
Washing tomatoes removes only surface bacteria, failing to eliminate pathogens in stem scars or internal tissues. Chlorine treatments show limited efficacy against internalized Salmonella , leaving consumers reliant on thorough cooking, a solution impractical for raw consumption.
Recent recalls highlight these ongoing vulnerabilities despite industry safeguards. These biological and operational factors converge, positioning tomatoes as recurrent vehicles for foodborne illness.
