The Dose Response Relationship

Author: From ‘The Science Behind Our Food”

Original Lessons

http://apps.caes.uga.edu/sbof/main/lessonPlan/IntroToToxicology.pdf

http://science.education.nih.gov/supplements/nih2/chemicals/default.htm. (Chemicals, the Environment and You)

Editor: Stephanie Nardei

Modified for PULSE by Patricia A. Wheeler and Marti Lindsey

Time: / 1 hour
Preparation Time: / 10 – 15 minutes
Materials: / Handout 5

Abstract

In groups, as a conclusion to the seed germination experiments, they will investigate the effect of a chemical (they choose) on the germination of seeds and will create a dose-response curve to interpret their observations and evaluate their hypothesis.

Objectives

Students will be able to:

1.  Define a “toxic substance.”

2.  Define the “science of toxicology.”

3.  Explain the dose-response principle.

4.  Explain toxicological principles that govern the safety of a substance.

5.  Analyze toxicological risks versus benefits of a substance based on their understanding of toxicological principles.

6.  Draw conclusions and evaluate hypotheses

National Science Education Standards:

Content Standard A – Science as Inquiry

§  Identify questions and concepts that guide scientific investigations

§  Formulate and revise scientific explanations and models using logic and evidence

§  Communicate and defend a scientific argument


Content Standard F- Science in Personal and Social Perspectives

Personal and community health

Arizona Science Education Standards:

Concept 1: Observations, Questions, and Hypotheses

§  PO 2. Develop questions from observations that transition into testable hypotheses.

§  PO 3. Formulate a testable hypothesis.

Concept 2: Scientific Testing (Investigating and Modeling)

§  PO 1. Demonstrate safe and ethical procedures (e.g., use and care of technology, materials, organisms) and behavior in all science inquiry.

§  PO 5. Record observations, notes, sketches, questions, and ideas using tools such as journals, charts, graphs, and computers.

Concept 3: Analysis, Conclusions, and Refinements

§  PO 2. Evaluate whether investigational data support or do not support the proposed hypothesis.

Concept 4: Communication

§  PO 2. Produce graphs that communicate data. (See MHS-S2C1-02)

§  PO 3. Communicate results clearly and logically.

§  PO 4. Support conclusions with logical scientific arguments.

Teacher Background

See Basic Toxicology under the Environmental Health Resources section of PULSE.

http://pulse.pharmacy.arizona.edu/resources/toxicology/teachers.htm

See also the background section for the ‘The Science Behind Our Food” unit http://apps.caes.uga.edu/sbof/main/lessonPlan/IntroToToxicology.pdf

Dose Response Relationships http://science.education.nih.gov/supplements/nih2/chemicals/guide/lesson3-1.htm

Related and Resource Websites

Dose-Response Relationships In Toxicology http://pmep.cce.cornell.edu/profiles/extoxnet/TIB/dose-response.html, an in-depth overview of dose-response

Green Facts Glossary http://www.greenfacts.org/glossary/def/dose-response-relationship-dose-response.htm, an overview of dose-response for certain chemicals and links to other toxicology terms

Health and the Environment: Food, Farming, & Pesticides http://www.nrdc.org/health/pesticides/default.asp

Develop a hypothesis http://www.k12science.org/curriculum/dipproj2/en/lesson1.shtml

Writing a hypothesis: a student lesson http://www.accessexcellence.org/LC/TL/filson/writhypo.html

Case Study: Polio http://www.the-aps.org/pa/animals/polio.html

Questions People Ask About Animals in Research http://www.the-aps.org/pa/animals/index.htm

Activity

Students will observe the condition of the seeds in each of their bags, recording the number that have germinated and the number that have not in their science notebooks.

1.  As the final day of their observations, students construct a dose-response curve to interpret their observations and evaluate their hypothesis using the Dose-Response Handout 5 is based on:

http://science.education.nih.gov/supplements/nih2/chemicals/guide/lesson3-1.htm

Dose-Response Curves

The characteristics of exposure to a chemical and the spectrum of effects caused by the chemical come together in a correlative relationship that toxicologists call the dose-response relationship. This relationship is the most fundamental and pervasive concept in toxicology. To understand the potential hazard of a specific chemical, toxicologists must know both the type of effect it produces and the amount, or dose, required to produce that effect.

The relationship of dose to response can be illustrated as a graph called a dose-response curve (Handout 5). There are two types of dose-response curves:

·  One that describes the graded responses of an individual to varying doses of the chemical

·  One that describes the distribution of responses to different doses in a population of individuals.

The dose is represented on the x-axis. The response is represented on the y-axis.

2.  Students will write a formal conclusion incorporating concepts relevant to the science of toxicology demonstrating their learning.

Embedded Assessment

Assess students’ ability to form and evaluate a hypothesis, discuss the concepts of dose, the use of animals in biomedical research and their formal conclusions, based on the experiment.


Homework

If applicable

1