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Arsenic and Old Lace
Lesson by
Sarah Kenyon

Time: 1.5 class periods
Prep Time: 15 minutes – photocopying Article
Materials: See Resources

 

Abstract
In this explore lesson, students learn about the origins, issues and problems associated with arsenic through history. The end goal of this learning cycle is to become more acquainted with the effects of arsenic poisoning, different ways that arsenic can get into someone’s system, and to make intuitive assessments of what the terms chronic and acute mean. They should also be able to discuss their own ideas about how the risk levels set by health agencies are determined.

Objectives
Students will:
1. Read about specific instances of arsenic in history and share these stories with each other.
2. Identify, after reading the articles and sharing, what role arsenic played, how arsenic enters the system and what its effects are.
3. Make assessments of what chronic and acute mean and assign each term to each story they have read.
4. As a class, discuss what counts as an acceptable risk of arsenic exposure in each case and identify what factors should be taken into account.

National Science Education Standards
CONTENT STANDARD F: Science in Personal and Social Perspectives
ENVIRONMENTAL QUALITY

  • Natural ecosystems provide an array of basic processes that affect humans. Those processes include maintenance of the quality of the atmosphere, generation of soils, control of the hydrologic cycle, disposal of wastes, and recycling of nutrients. Humans are changing many of these basic processes, and the changes may be detrimental to not only to the human populations, but also to the environment.
  • Many factors influence environmental quality. Factors that students might investigate include population growth, resource use, population distribution, overconsumption, the capacity of technology to solve problems, poverty, the role of economic, political, and religious views, and different ways humans view the earth.

NATURAL AND HUMAN-INDUCED HAZARDS
ß Some hazards, such as earthquakes, volcanic eruptions, and severe weather, are rapid and spectacular. But there are slow and progressive changes that also result in problems for individuals and societies. For example, changes in stream channel positions, erosion of bridge foundations, sedimentation in lakes and harbors, coastal erosions, and the continuing erosion and wasting of soil and landscapes can all negatively affect society.

Teacher Background
Teachers should have read the articles and be aware of the effects of arsenic poisoning.
Arsenic through history:
There are a number of different sources of arsenic “contamination” of the environment- geological processes (aided or not aided by humans), mine tailings, and pesticide deposition. Mine tailings and pesticides are an important part of the whole picture, but the more interesting and challenging problem of environmental levels of arsenic is from the first category, geological processes.
Arsenic finds its way into our drinking water and our bodies from different geological processes to different chemical reactions that take place, modulating that level of available arsenic and its effects. It is important for students to take away this picture- of a complex network of environmental influences, the ‘abiotic ecology’ of arsenic , as well as how the picture continues to come into focus. They will do this by learning how we get a picture of what is going on through the effects on people (this learning cycle) as well as how the levels are set and the regulations are enacted through remediation and legal consequences.
General background: http://www.dchtrust.org/arsenic_king_of_poison.htm

Related and Resource Websites
Killer wallpaper: http://www.popularscience.co.uk/features/feat17.htm
Madness of King George (antimony, arsenic and porphyria): http://news.bbc.co.uk/1/hi/health/3889903.stm
The many faces of arsenic: http://news.bbc.co.uk/1/hi/health/medical_notes/459078.stm
US rice: http://www.nature.com/news/2005/050801/full/050801-5.html
Medical- current: http://phys4.harvard.edu/~wilson/arsenic/Image_Makeover1.htm
General: http://www.dartmouth.edu/~toxmetal/TXSHas.htm

 

 

Activity
1. As students walk in, you should have the following question on the board: “Have you heard of arsenic poisoning?’ What does this phrase make you think of?” Give them 5 minutes to write down their answers.

2. Call on students to read their answers and categorize them on the board. This allows you to get an idea what the students’ prior knowledge is. You may have to prompt them or ask leading questions to get them to think a bit more broadly, as the previous lesson will have alerted them to arsenic as a contaminant in the water supply.

3. Once you have given the class a glimpse of what their classmates have thought of, pass out one article per student for a 15-25 minute reading time. Have the students highlight one sentence that strikes them as the most important in their article.

4. Gather students who have read the same article into groups. Within groups, students will share their sentences, and then will come up with a summary of the article as a group.

5. Partway through their discussion, put the following labels on the board: Textiles, medicines, geology, pesticides, mining, other. Tell students that, along with their summary, they must identify the term that matches the role of arsenic in their article.

6. Within each group, students will be numbered 1-4 (or 5 if there are more students) and then through a jigsaw be placed in groups where each article is represented. They will then share their article’s summary and term with the group.

7. When the groups complete their discussion, each article’s title and term will be read for the class.

8. The teacher should post each article along with the term chosen by the group on the wall.

Chronic vs. acute (day 2)
9. Ask students to define the word “chronic” on a sheet of paper.

10. Ask students to define the word “acute” on a sheet of paper.

11. Collect the papers

12. Give the terms and their definitions on the board.

13. Have the students, as a class, decide which term fits each arsenic article.

14. Ask the students to identify factors that are important in assigning each article (dosage, time exposed, how people were exposed, effects of the poisoning, chemical state of the arsenic, etc.)

15. Ask students to give ideas about how much arsenic is an acceptable risk in each case. Does this differ from case to case? Why or why not?
.

Homework
Have students answer one of the following questions in a one page essay:
A) How has the view of arsenic changed over time, and what do you expect in the future?
B) How would you educate someone on the risks of arsenic?
C) What more do you need to know to make educated decisions about arsenic levels in your water supply?

Embedded Assessment

This lesson allows a teacher to assess student preconceptions about arsenic, and the definitions of ‘chronic’ and ‘acute’. It gives the students a wide ranging view of arsenic though history and to synthesize this information in ways to help them make decisions about acceptable risk and regulation of arsenic exposure to humans. By attacking the arsenic problem at an historical level, students see how our knowledge of arsenic has changed over time.



PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:


an
NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award

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Supported by NIEHS grant # ES06694


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