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Lesson 1-Chemicals, Chemicals, Everywhere
Engage

ACTIVITY 3: CASE STUDIES OF ROUTES OF EXPOSURE

National Science Education Standards icon Content Standard E:
Students should develop understandings about science and technology.
Content Standard F:
Students should develop understanding of natural hazards, and risks and benefits.

Content Standard G:
Students should develop understanding of science as a human endeavor.

1. Set up the class so that each team of students has access to a computer, such as in a computer lab. Instruct teams to do the activity titled What's Wrong Here? on the Web site. Circulate around the room and listen as groups work through each situation.

Web activity iconTo view the activity, open the Web site in your browser (see instructions for using the Web site). From the main page, click on Web Portion of Student Activities, then Lesson 1—Chemicals, Chemicals, Everywhere and select What's Wrong Here?

2. Tell students that now they will consider some true chemical exposures.

Display a transparency of Master 1.4, Questions for Case Studies. Then, distribute a copy of Case Study #1 from Master 1.5, Case Studies of Routes of Exposure, to each student.

3. Ask students to work in teams and to read Case Study #1. Instruct them to answer the questions on the transparency in their science notebooks.

4. Once teams have read and answered the questions about Case Study #1, conduct a class discussion about the case study by answering the questions on the transparency.

Sample Answers to Questions for Case Study #1 on Master 1.4

Question 1. What happened? Where did it happen? When did it happen?

A Dartmouth College scientist died of mercury poisoning in 1997 in New Hampshire after being exposed to the chemical in 1996.

Question 2. What chemical was involved?

The chemical was dimethylmercury (die-METH-ul-MER-kyoo-ree).

Question 3. What was the route of exposure?

The route of exposure was absorption through the skin.

Question 4. What were the symptoms of toxicity?

The symptoms of toxicity were permanent nervous system damage, numbness of fingers, unsteady walking, difficulty speaking, blurred vision, hearing problems, coma, and death.

Question 5. How could a person have prevented his or her exposure to the chemical?

Answers will vary. The researcher used precautions thought to be adequate at the time.

Question 6. Have any changes occurred since the incident? Describe them.

Researchers now know that dimethylmercury can seep through latex gloves. They now use neoprene gloves with long cuffs or wear two pairs of gloves, one of them laminated and one of them heavy duty.

assessment iconThis is a good time to assess your students' understanding of the three ways chemicals can enter the human body and cause harm: ingestion, inhalation, and absorption.

5. There are four more case studies, two describing chemical exposure through inhalation and two describing chemical exposure through ingestion. Continue to have students read, discuss, and answer the questions about each case study.

Tip from the field test: Give a different study to each team and ask the teams to read their study. Then, instruct teams to present their case study to the class. Teams can explain their case study and answer the questions from the transparency so that everyone in the class learns about the case and discusses the route of chemical exposure. The case studies vary in length, allowing you to individualize the reading assignment for students of varying reading abilities.

Sample Answers to Questions for Case Studies #2–5 on Master 1.4

Case Study #2

Question 1. What happened? Where did it happen? When did it happen?

Gas leaked from a chemical plant in 1984 in India.

Question 2. What chemical was involved?

The chemical involved was methylisocyanate (METH-ul-EI-soh-SIE-uhnaet).

group of Indian men
Photo: © Bettmann/CORBIS

Question 3. What was the route of exposure?

The routes of exposure were inhalation and absorption through the eyes and the nose.

Question 4. What were the symptoms of toxicity?

The symptoms of toxicity were eyes and lungs burning, vomiting, lung impairment, loss of motor control, neurological disorders, and damaged immune system.

Question 5. How could a person have prevented his or her exposure to the chemical?

Answers will vary. Students should recognize that people who lived in Bhopal had little choice over their exposure. People could have made the choice not to live near a chemical plant.

Question 6. Have any changes occurred since the incident? Describe them.

The chemical plant was sold to a company in Calcutta. Proceeds from the sale supported hospitals and clinics in Bhopal.

Case Study #3

Question 1. What happened? Where did it happen? When did it happen?

Jane had lead poisoning; it happened in her home during her first two years of life.

Question 2. What chemical was involved?

The chemical involved was lead.

Question 3. What was the route of exposure?

The route of exposure was ingestion.

Question 4. What were the symptoms of toxicity?

The symptoms of toxicity were abdominal pain, constipation, vomiting, and lethargy; in severe cases, learning disabilities, decreased growth, hyperactivity, impaired hearing, and even brain damage can occur.

Question 5. How could a person have prevented his or her exposure to the chemical?

Prevention for children includes annual blood tests to check lead levels; clean play areas, floors, windowsills, and hands; professional paint removal; and drinking of milk.

Question 6. Have any changes occurred since the incident? Describe them.

Students can assume that Jane's mother acted on the doctor's suggestions for minimizing the family's exposure to lead.

Case Study #4

Question 1. What happened? Where did it happen? When did it happen?

Jimmy Green died from sniffing gasoline in the spring of 1999.

Question 2. What chemical was involved?

The chemical was gasoline.

Question 3. What was the route of exposure?

The route of exposure was inhalation.

Question 4. What were the symptoms of toxicity?

The symptoms of toxicity were short-term memory loss, hearing loss, arm and leg spasms, permanent brain damage, liver and kidney damage, and death.

Question 5. How could this person have prevented his or her exposure to the chemical?

Jimmy Green voluntarily exposed himself to gasoline fumes. He could have prevented his exposure by choosing not to sniff gasoline.

Question 6. Have any changes occurred since the incident? Describe them.

Parents and students are now informed of the dangers of inhalants.

Case Study #5

Question 1. What happened? Where did it happen? When did it happen?

In 1971, more than 6,500 people were poisoned in Iraq.

Question 2. What chemical was involved?

The chemical was methylmercury (METH-ul-MER-kyoo-ree).

Question 3. What was the route of exposure?

The route of exposure was ingestion.

Question 4. What were the symptoms of toxicity?

The symptoms of toxicity were nervous system disorders.

Question 5. How could a person have prevented his or her exposure to the chemical?

If people had been better informed, they would have planted the seed instead of eating it.

Question 6. Have any changes occurred since the incident? Describe them.

No changes were mentioned in the case study, but students might discuss the need for better warning labels and instructions for grain shipped between countries.

bread, bags of grain and flour Photo: © Bettmann/CORBIS

Extension Activity

Ask students to find current event stories in newspapers, magazines, or television programs that talk about chemical exposure. Challenge students to find one event that involves a chemical exposure that harms humans or other living things and one that involves a chemical exposure that benefits humans or other living things.

You will be able to use a chemical exposure described in these articles in the extension activity in Lesson 5.

Tip from the field test: If students in your school are required to bring in current event articles for several other classes, coordinate with teachers making similar assignments so that students are not duplicating efforts. Alternatively, collect articles yourself and display them in the classroom.

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