Toxicity indicates how poisonous a substance is to biological organisms. To measure a chemical’s short-term toxicity, scientists carry out something called a “dose/response” study. The word dose refers to the total amount of a substance to which an individual is exposed through the mouth, lungs, or skin. Your total dose of a chemical includes the amount of the chemical that you eat, either by itself or contained in food or drinks, and the amount that you inhale with the air you breathe. It also includes absorption through your skin. All of these sources together make up your exposure to the chemical. This free selection includes the Table of Contents and Preface.