Chemicals & Human Health

Toxicology Problem Set

Problem 7: Dose and response

For help to answer the question:

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 same amount of harm/sickness.
C. Exposure to the hazard always results in harm.
D. Fifty percent of the people will die when exposed to 0.1 mg/kg.


The amount of damage (response) caused by a chemical that has entered the body depends on the dose, or amount entering the body, and the relationship follows a predictable pattern. At very low amounts, there will be no detectable effect of the chemical. In the midrange of doses, the amount of damage will increase as the dose increases. At very high doses, a maximum level of damage is reached.

This is dose-response curve for a common chemical called ethyl alcohol, the kind of alcohol in alcoholic beverages. At low doses the effects of alcohol are familiar and are not life-threatening, but may still be very dangerous. At higher doses, alcohol is extremely toxic to humans and can cause death.

Toxicology Problem Set Chemicals & Human Health

The Southwest Environmental Health Sciences Center
The Biology Project
The University of Arizona
Tuesday, September 16, 1997
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