"The greater concern is with pathogenic microorganisms -- which can be bacteria, viruses, or parasites," Dr. Bunning explains. "A high number of foodborne illness outbreaks have been attributed to fresh produce because there are so many opportunities for contamination in the growing environment and after harvest."
Where do these damned microorganisms come from?
Thinking about the "farm-to-table" path of your broccoli, you have to consider the soil it was grown in, the water that was used, how it was stored, transported, and handled in the grocery store, with potential for contamination at every step of the way. If you're one of those five-second-rule naysayers who washes an apple a little longer after dropping it and watching it roll along the unwashed kitchen floor... don't kid yourself. You have no idea where else it's been.