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INTRODUCTION TO TOXICOLOGY Background Information for “Toxicity Testing with California Blackworms and Alcohol” Created by Stefani D. Hines with modifications by Debbie Gevirtzman, SWEHSC, University of Arizona Toxicology • What is it? • How is it used? Toxicology • The study of harmful effects of chemicals on living systems Toxicology • • • • • • • Biology Chemistry Physiology Physics Statistics Immunology Ecology • • • • • • • • Forensic Medicine Clinical Treatments Drug Development Public Health Industrial Hygiene Veterinary Science Agriculture Environmental Science CONGRATULATIONS! You are already toxicologists! Hazard • A chemical substance, physical agent, or biological agent that can harm the health of people Exposure • Contact with a hazard Routes of Entry Routes of Entry • Ingestion – chemicals can enter the body by eating or drinking • Inhalation – chemicals can be breathed into the lungs • Absorption - chemicals can enter the body by moving through the skin Dose • Dose is the amount of a chemical that gets inside of your body. • Measured in mg of chemical/kg or lb of weight Dose: A Visual Explanation Who took the largest dose of Tylenol? Weight: 125 lb Tylenol: 300 mg 135 lb 600 mg 20 lb 5 lb 100 mg 50 mg Calculating Dose: 50 mg 5 lb = 10 mg/lb 300 mg 125 lb = 2.4 mg/lb The Dose Makes The Poison “What is it that is not a poison? All things are poisons and nothing is without poison. It is the dose only that makes a thing not a poison.” Paracelsus, 1493-1541 Most hazardous substances exhibit a “dose-response” relationship. What does this mean? A. The harm caused by the hazard increases as the amount of hazard entering the body (dose) increases. B. It does not matter how big a dose you receive, you will always have the same amount of harm/sickness. C. Exposure to the hazard always results in harm. Dose-Response Curve for Alcohol Response Death Labored breathing Unconscious Deep sleep Sleep Giddy No effect Dose Dose-Response Curve for Vitamin D Response Toxic Healthy Unhealthy Dose Exposure • Exposure Frequency – how often • Exposure Duration – how long • Exposure Concentration – how much For a Chemical to Affect You • Exposure • Dose Toxicity • Acute Toxicity – a high toxicant dose over a short period of time • Chronic Toxicity – a small dose of a toxicant over a long period of time Factors Affecting Toxicity • Extrinsic Factors – occur outside the body • Intrinsic Factors – occur within an individual organism Intrinsic Factors • Age • Genetic Difference • Body Size Control • Our biggest chemical risks are with things we have control over Control • Food • Exposure to Known Hazards in Daily Lifestyle – Cigarettes – Alcohol • Preventable Poisonings Factors Contributing to Cancer Risk in the U.S. • • • • • Diet ~35% Tobacco ~30% Occupational exposures & pollution ~5% Infection (viruses) ~10% Other ~20% – Genetic susceptibility – Sun/radiation – Alcohol And now, let’s do the blackworm lab!
