What is Arndt-Schultz law?

The Arndt-Shultz Law summarizes experiments which measure the physiological response of a living organism to a stimulus. It says a small amount of a chemical or electrical or laser or other stimulus will increase physiological activity, a large amount of the same stimulus will kill cells of the organism, and an intermediate amount will inhibit physiological activity.

In brief: the physiological response reverses direction when the stimulus changes from small (weak) to large (strong), and vice-versa.

An example of the Arndt-Shultz Law in action is the 1944 observation that a large dose of penicillin will kill a Staphylococcus infection, while a small dose will stimulate its growth.

The Arndt-Schultz Law applies only where there is a dose-dependent reversal of the physiological effect on an organism, from beneficial to harmful, or vice-versa.

In the case of Vitamin C, the reversal has occurred by the time the dose causes bowel intolerance.

In the case of radiation in the environment from cosmic rays or nuclear fission or from decay of radioactive materials, in the development of protective standards, it was assumed by the U.S. Environmental Protection Agency and the U.S. Atomic Energy Commission that zero radiation is the only beneficial level of radiation. This assumption is contrary to the evidences that support the Arndt-Schultz Law.

Submitted by David Langford, 18 March 2008.