Toxic Chemicals and Living Systems

Toxic Chemicals and Living Systems Photo Credit: Keith Weller, Agricultural Research Services, USDA


You or your parents may have used pesticides or herbicides on the plants in your yard. Or, perhaps you have some houseplants that you have used chemicals like Miracle Gro® on. Have you ever read the labels on these products? Are there warnings about potential harmful effects of these chemicals? How do you think the developers of these products have determined the safe ways in which they can be used? This lesson will introduce you to the science of toxicology, which studies the effects of drugs, environmental contaminants, and naturally occurring substances found in food, water, air and soil and the use of that information to predict safe exposure levels.


Choose one of the chemicals you listed as a poison on your Some Basic Principles of Toxicology student sheet. Perform research to answer the following questions for that poison on a separate sheet of paper. Some website suggestions are provided below.

  • What is the name of the chemical?
  • How is this chemical traditionally used?
  • Where is this chemical found?
  • At what dose is this chemical toxic?
  • What organism(s) does this toxic chemical affect?
  • Describe, in general terms, the mechanism of action for this toxic chemical.
  • Using the diagram “Toxicology at Every Level of Biological Organization,” state how this toxic chemical affects each level of the biological system (macromolecules, organelles, cells, tissues, organs, organisms, populations, communities, ecosystem, and biosphere).

Suggested Websites for Online Research

Arizona Poison & Drug Information Center
This site provides a great long list of “Tox-Trivia” questions, sections on poisons in the home, poisoning and pets, toxic plants, venomous critters, hazardous materials, plus news and statistics.

The Bad Bug Book
This site from the U.S. FDA Center for Food Safety & Applied Nutrition has a wealth of information on food-borne pathogens as well as natural toxins. Find reference material (diseases, target populations, history of recent outbreaks, etc.) on mushroom toxins, shellfish toxins, tetrodotoxin from pufferfish, and many others.

ExToxNet: The Extension Toxicology Network
This site provides a rich source of information on pesticides. Included is a huge glossary, Toxicology Information Briefs (on bioaccumulation, carcinogenesis, and many more), Pesticide Information Profiles (on nearly 200 active ingredients), Toxicology Issues of Concern, news, and more.

This esheet is a part of the Toxicology 1: Toxicology and Living Systems lesson.

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