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 135 lb 20 lb 5 lbTylenol: 300 mg 600 mg 100 mg 50 mg

Calculating Dose:

300 mg 125 lb = 2.4 mg/lb

50 mg 5 lb = 10 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

Dose

Res

pon

se

No effect

Giddy

Labored breathingUnconscious

Sleep

Deep sleep

Death

No effect

Dose

Res

pon

seDose-Response Curve for Vitamin D

Toxic

Healthy

Unhealthy

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!