There is compelling evidence from a multitude of studies of various design indicating that foodborne excitotoxin additives can elevate blood and brain glutamate to levels known to cause neurodegeneration and in the developing brain, abnormal connectivity. Excitotoxins are also secreted by microglial activation when they are in an activated state. Recent studies, discussed in part 1 of this article, indicate that chronic microglial activation is common in the autistic brain. The interaction between excitotoxins, free radicals, lipid peroxidation products, inflammatory cytokines, and disruption of neuronal calcium homeostasis can result in brain changes suggestive of the pathological findings in cases of autism spectrum disorders. In addition, a number of environmental neurotoxins, such as fluoride, lead, cadmium, and aluminum, can result in these pathological and biochemical changes.