As a child, you were probably told to wash your hands before you ate. As an adult, you need to wash your hands and what you eat. Agricultural use of pesticides has doubled over the past two decades, despite research linking certain chemicals to nerve damage, genetic defects, and cancer. Since you don't know which fruits and vegetables have been contaminated with what poison, the ideal preventive measure is to eat only produce you grow yourself, without use of pesticides. But that's not practical for most people. In lieu of that:

• Whenever possible, buy domestically grown produce instead of imported.
  
• Studies have shown that produce grown in the United States contains lower levels of contaminants than foods grown outside the country.
  
• Be especially careful with peaches, celery, cherries, strawberries, and lettuce. A study conducted by the Natural Resource Defense Council, a San Francisco-based consumer group, found that these items were more likely to be contaminated than others. Corn, cauliflower, bananas, and watermelon
  were less likely to be affected.
  
• Wash fruits and vegetables in soapy water. Rinse thoroughly. then dry.

SOURCE: "Nutrition Action Health Letter," vol. 16, no. 3. (Washington, D.C.: Center for Science in the Public Interest, April, 1989).