Ever since humans discovered fire, our activities have been releasing a "dog's breakfast" of unnatural chemistry. The list has grown to well over 75,000 free elements, compounds and pharmaceuticals. Many of these are acidic, electron-hungry oxidants and free radical generators.
Conventional medicine seems to dismiss industrial pollutants, food additives, personal care products, household cleaners, building materials and pharmaceutical residues... unless lethal concentrations are involved. The fact is, many are cumulative, so even at tiny parts per billion or million concentrations, poisonous substances considered "safe" by the EPA collect in fat, brain and bone, even crossing the placental barrier into rapidly differentiating embryonic tissues.
There they compromise cell membranes, damage DNA and the enzymes it produces, affect nerve conductivity, alter glandular production and hormonal balances, and continually generate free radicals which attack chemical bonds that hold all cell structures together. We don't want our cell structures to fall apart.