Because most produce is grown by local farmers, the fertilizer used to grow them is very inconsistent. The water they are rinsed in prior to sale is also contaminated in some way - either with chemical or biological waste. Fertilizer is part animal waste. Irrigation water often contains human waste.
We follow a few simple rules: Our neighbors have helped us find the best markets and we try to use consistent vendors. Our driver helps us get better prices.
The best way to prevent illness is to simply wash your vegetables when you bring them home. We soak them for about 10-20 minutes in a product called, "Steriliq." It is a mild solution of essentially bleach and water. As the bottle says, it was originally designed to sterilize baby bottles but it works great on produce as well. Steriliq kills most of the surface bacteria. Then we rinse the veggies with filtered (RO) water and let them air-dry on the counter before we place them in the refrigerator.This time of year the produce dries in a very short time! And as you can see, the vegetables are very fresh and nice. The whole process probably takes about 45 minutes.
Obviously we cook most of our vegetables, but we do sometimes eat raw cucumber, tomatoes, and many fruits. No major problems so far!