#754 - Paracelsus Revisited

For more than 450 years, toxicologists have relied on an idea expressed by Paracelsus in the fifteenth century: "The dose makes the poison."[1] By this, Paracelsus meant that everything is poisonous in a high enough dose and, "Even strong poisons are harmless if the dose is low enough." Implicit in these two ideas is a third, "The higher the dose, the stronger the poison." Together, these ideas have been used to justify dumping billions of tons of biologically-active chemicals into the environment each year: even the most active were considered OK to dump because they would be diluted by air and water down to doses that were considered safe.