What is the most important determinant of toxicity?

Toxicity is the quality or degree of being toxic or poisonous. The dose of a substance is the most important determinant of toxicity. Dose by definition is the amount of a substance administered at one time. The most important are the number of doses, frequency, and total time period of the treatment. Types of doses include: 

• Absorbed dose: the amount of a substance that entered the body through the skin, eyes, lungs, or digestive tract and was taken up by organs or particular tissues. Absorbed dose can also be called internal dose.
• Administered dose: the quantity administered usually orally or by injection (note that an administered dose taken orally may not necessarily be absorbed).
• Total dose: the sum of all individual doses.