Between the farm and the dinner table, Friedman points to many places where contamination can occur:
- Production: Contamination can come from irrigation water or manure in the field.
- Harvest: Poor sanitation facilities -- latrines and hand-washing stations -- contribute to contamination from workers. People who harvest produce should be considered food-handlers and take the same precautions as restaurant workers or supermarket employees.
- Initial processing on the farm: Contamination can come from water used to wash the fruit. Open processing sheds can lead to contamination from birds, rodents, and amphibians.
- Distribution: Contamination can come from dirty trucks or from ice used for cooling. One outbreak came from a truck used to transport raw eggs that subsequently took on a load of orange juice.
- Final processing at the factory, restaurant, or supermarket: The longer the time since processing, the greater the chance of contamination. Cross contamination can occur from meats and other products. Improper storage temperature also can encourage the growth of bacteria.
"It makes me think more about eating these salads," Barbara E. Murray, MD, tells WebMD. "With salads, there is not a good way to eliminate contamination, but you really can't avoid them because they are so good for you. I feel more strongly about raw juices -- there are adequate ways to control these, and there are optional products such as pasteurized juice."
Murray, chief of infectious diseases at the University of Texas Medical School in Houston, warns that pregnant women should be cautious about eating cheese, milk, and certain deli products that might be contaminated with a bacteria known as listeria, which can cause a brain infection in newborns.
Friedman acknowledges that there are limits to how many foods a person can avoid. "I would eat a mango -- but I wouldn't eat sprouts or drink raw or unpasteurized juice because I am pregnant," she says.