Foodborne illness has increased in recent years, and is emerging as a global health threat reports Marilyn Larkin in her May 30th, 2008 article "Roots of Foodborne Illness: Health Threats from Domestic and Imported Produce". Several large-scale out breaks of Salmonella infection in the United States have drawn attention to the issues and problems.
Foodborne Infections From Produce and Plants
Larkin summarizes the speech of the FDA's Robert Buchannan from a meeting at the New York Academy of Sciences: produce and plant associated products account for most of the foodborne infections in the United States. The types of foodborne infections seen usually differ depending on whether the produce is domestic or imported. When domestic produce has been infected, mainly E. coli and Salmonella infections, which are zoonotic (animal based) in origin, are detected.
Buchannan further stated that the pathogens affecting imported produce are human pathogens such as Hepatitis A, Norovirus, and Shigella, although scientists are discovering cross-over infections and less common strains of foodborne illness are beginning to be seen due to the increase in importation of exotic foods.
Indirect Contamination of Food
Sanitation practices vary worldwide and can affect the produce at the growth, harvesting, packaging, or distribution stages of production according to Larkin's article.
Bacteria can also contaminate the inside of fruit, not just the outside, as some people believe. Pathogens causing foodborne illness can find their way into produce through the bloom, which can become contaminated during pollination. The plants can also absorb bacteria through the roots, which invade all of the plant tissue, but don’t harm the plant itself.
The water used to wash produce before packing can be a potential problem if it is contaminated with bacteria. The produce absorbs water during washing, drawing bacteria into the foodstuffs.
Any produce that is cut, diced, sliced, or peeled can be contaminated by bacteria. This effectively wounds the produce and the cut areas begin to break down and become vulnerable to pathogens. In addition, the cut areas provide a greater surface area upon which pathogens can grow.
Temperature extremes that are common as produce makes its way from field to supermarket contribute to contamination. When produce remains unrefrigerated, bacteria multiply.
The points made in Larkin's article are further supported by an article in Emerging Infectious Diseases Oct./Dec. 1997 titled "Produce Handling and Processing Practices" by Larry R. Benchat and Jee-Hoon Ryn. Indirect contamination can result when food safety practices mandated by food regulatory agencies are not carried out by food handlers, such as proper use of gloves to handle food, working while ill, or not keeping food at appropriate temperatures.
Direct Contamination of Food
Benchat and Ryn also note that outbreaks of foodborne illness can be linked to various types of animal contamination of produce or growing fields. Changes in the way land is used can contribute to contamination and foodborne infection. Larkin's comments echoed this fact when she mentioned cattle grazing on hills above flat areas can cause contamination when gravity sends E. coli racing down the hills with the next rain. The increased size of farms means that a greater percentage of produce is at risk for contamination. The intermingling of fields with cities yields more opportunities for contamination as bacteria can be transferred upon the feet of both humans and animals as they enter and exit the fields.
Larkin mentions the speech of Charles Gerba at the Academy, relating how irrigation channels can frequently become contaminated with E. coli and Salmonella. Organic produce is not immune to foodborne contamination either as organic farmers often must rely on water sources from irrigation channels.
Food Safety is Complex
Larkin explains that the United States is trying to inspect imported produce at points of entry, but that the experts speaking at the Academy meeting acknowledge that trying to ensure safety in even one area is not a straightforward process due to the many different modes of contamination.
