The right dose differentiates a poison and a remedy.
The past century has seen a tremendous expansion in the number of synthetic chemicals employed by humankind as materials, drugs, preservatives for foods and other products, pesticides, cleaning agents, and even weapons of war. The American Chemical Society maintains a chemical registry. Since 1907, it has recorded 33 million organic and inorganic substances and 58 million sequences as of 2008. About 4000 new chemicals are added each day. A study by the Danish Environmental Protection Agency calculated that 13.4% of them possess acute toxicity, 2.5% reproductive toxicity, 3.9% are mutagens, 1.8% carcinogens, ...