Those samples are sent to a lab in Los Angeles where they are tested for safe levels of about 300 pesticides. Produce that tests positive for unsafe pesticides must be destroyed or the distributors face stiff fines. One problem in testing for these bacteria is that microbial contamination does not typically affect all produce harvested from one farm, as is the case with pesticides. One carton of strawberries on a truck, for example, might have traces of cyclospora, while the rest could be untainted. By then, shipments may already be in stores.
Experts disagree about whether such extensive testing of imported produce is really necessary.
And there is no reliable data to show that imported food is more dangerous than domestic produce. The changes have more to do with consumer demand than with unsanitary growing conditions. A generation ago, few housewives would pay high prices for fresh fruits and vegetables in the winter. Jell-O was substituted for salads, frozen vegetables for fresh, and canned fruit cocktail was for many the dessert of choice. And inevitably, the number of inspections will not keep up with the volume.