If you buy produce at the farmers' market or grow it yourself, then you're certainly acquainted with one fact: vegetables are dirty... in the truest sense of the word! Grown in soil and freshly harvested, market and garden vegetables are a far cry from their squeaky clean grocery store counterparts. But before you scrub those carrots and rinse those tomatoes, consider this: that dirt may be keeping you healthy.According to a recent article by Jeff D. Leach for The New York Times, the greatest social contribution of the farmers' market isn't the farm-to-table model or its seasonal goodness (although those are all great things!); rather, it's its role "as a delivery vehicle for putting dirt back into the American diet and in the process, reacquainting the human immune system with some 'old friends.'" - i.e. the billions of microorganisms that live in dirt. Leach suggests that decades of sanitizing our food (and ourselves) is at least partly responsible for the alarming rise in allergic and autoimmune diseases in recent years, and thus "reintroducing some of the organisms from the mud and water of our natural world would help avoid an overreaction of an otherwise healthy immune response."