In this chapter, only human-made pesticides will be discussed, even though more than 99.9% of the pesticides that we consume in our diets are natural [1], as are many bacterial toxins and other natural substances that help prime the innate immune system and strengthen our natural defenses against infection and disease [2]. Mechanisms evolved to do this. However, human-made pesticides and other environmental toxins have not been around long enough for protective mechanisms to evolve, and they may contribute to the large increase in autoimmune diseases in recent decades [3–6].