A bit more than 500 years ago, Paracelsus was born in the Switzerland, in a time when medicine was still viewed by many as the four bodily humors: blood, yellow bile, black bile, and phlegm. Paracelsus was the first to recognize the concept of a dose-response and that some toxic chemicals, like metals, when given at a low dose might be curative.

Recognize a chemical which describes Paracelsus's significant principle of toxicology: "the dose makes the poison". In another word, pick a chemical which is toxic at one kind of exposure, however beneficial with other kinds of exposure. For illustration, warfarin is used in the humans as a drug for blood-clotting and as a poison for rodents.

Describe the numeric value for the margin of safety for Fluoride? Show your computations and describe your reasoning.

a) What is the toxic dose for Fluoride?

b) What is the safe or beneficial dose for Fluoride?

I have decided on fluoride. I understand the math and margin of safety and can describe my reasoning however need help in finding out the numbers for toxic and safe dose for fluoride (ex: 5mg toxic) so that I can do the computations by myself. Please give creditable references for where the numbers were found.