Transcript Chemicals and Human Health

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!