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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
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Biology
Chemistry
Physiology
Physics
Statistics
Immunology
Ecology
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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.
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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!