This review published in the International Archives of Allergy and Immunology gives a good description of how certain chemicals and metal ions can interact with proteins in our body to become recognizable to white blood cells, triggering inflammatory allergic or autoimmune disease. Key point: it doesn’t have to be enough of a chemical or metal like mercury to cause a toxic (metabolically poisonous) effect—in a susceptible individual a relatively small amount of something in our food, environment or vaccine can set in motion a chronic disease. What makes a person susceptible? Various factors are evaluated in the functional medicine model.