access to library and Internet resources
Estimated Time to Complete Lesson
1 class period to setup activity (steps 1-3), 24-hour period for students to collect data, 1 class period to discuss data, 2-3 hours for research, and 1 class period for sharing results and follow-up discussion.
Over the past 50 years, synthetic chemicals increasingly have become a part of our everyday lives. In many cases, these chemicals make daily life easier and better. They help keep our homes clean, kill pests, and increase food production. But the toxic effects of many of these chemicals are poorly understood, especially regarding children. With an increasing number of childhood incidences of asthma, cancer, and learning and behavioral disabilities, scientists are turning their attention to understand what effect synthetic chemicals may be having on children.
KIDS AND CHEMICALS, a special report on NOW with Bill Moyers, takes a look at some of these medical maladies affecting children. The program features medical investigators and health officials engaged in the latest research on links between childhood illness and the synthetic chemicals children come in contact with each day.
Whether and how a synthetic chemical affects an individual depends on a number of factors, including the type of substance, the amount of exposure, the person's general health and genetic predispositions, and when during his or her lifetime the exposure occurs. Scientists are just beginning to conduct long-term, in-depth studies to determine some of the effects of exposure to synthetic chemicals. The National Children's Study is a proposed research effort that will look specifically at the risks children face. For more information about the study, see: The National Children's Study Web site (http://nationalchildrensstudy.gov/about/rationale.cfm)
This lesson will help students to become more aware of some of the synthetic chemicals they may encounter during their daily routine and to investigate what is and is not known about the toxicity of those chemicals.
Some of the synthetic chemicals students will probably note include:
Pesticides found on fruits and vegetables; household cleaning products such as bleach and oven cleaners; paint; arts and craft glues; chemical air fresheners; and beauty products such as fingernail polish remover.
Some synthetic chemicals they may not have considered may include:
Second-hand exposure to smoke from cigarettes; air-borne chemicals from automobile exhaust, industrial releases, and other sources; alcohol; and toxins, such as PCBs, that accumulate in the skin and fatty areas of fish, poultry, and meat. (You may also want to note to students that some chemicals that occur naturally can also be hazardous, such as radon gas.)
1. Before beginning the lesson, have a class discussion about what students think of when they think of the word chemical. Students might respond with answers related to synthetic chemicals, such as pesticides. Point out to students that not all chemicals are synthetic. They, and the world they live in, are naturally made up of chemicals chemicals comprise the air students' breathe, the water they drink, and the food they eat. However, there are also synthetic chemicals, those that are created by humans for various purposes. This program and lesson mainly focuses on these.
2. To help students get acquainted with synthetic chemicals they may find in their environment, have them read the following:
Have students read this page to discover the various types of Pollutants/Toxics that are classified by the Environmental Protection Agency (such as agricultural chemicals, chemicals found in consumer products, micro-organisms, and water pollutants).
Students can read this page to learn what pesticides are; what their effects are on child, food, and health safety; and the types of pesticides that exist.
Have students review the terms in this glossary (http://www.pbs.org/now/science/kidslaws.html). Clarify any definitions students do not understand.
3. Once students have had a chance to learn more about the types of synthetic chemicals in the environment, have students come up with a list of categories (such as cleaning agents; pesticides; fuels; industrial releases into air and water; preservatives; etc.) and discuss with them some places they may encounter synthetic chemicals that would fall into these categories. Doing this will help students to become aware of looking for chemicals in all the places they might travel (i.e., not just in their homes or classrooms, but also on the routes to and from school and within restaurants or other places they may visit).
4. Provide each student with a copy of the Synthetic Chemical Exposure Chart activity sheet. Review the chart with students and decide on the 24-hour period in which they will record their data.
5. Once students have collected their data, have a class discussion on the types of synthetic chemicals they recorded. List the categories students previously brainstormed, adding an "Other" category for findings that do not fall under listed categories. Have students report their data; as each synthetic chemical exposure is listed, poll students to find out how many of them experienced that same exposure. Tally the results for each exposure.
After students have reported their results, add any potential exposures that students might not have considered (see Background Information for ideas). Ask students if they remember being exposed to any of the newly listed chemicals and tally those responses.
Have students consider the following:What is known about its toxicity for adults and for children?
7. Once students have conducted their research, have groups present their findings.
8. To complete the lesson, assign students to write a one-page summary listing what they have learned. Follow-up with a class discussion. What was most surprising to learn? What questions do students still have that they would like answered? How might students set up a scientific study to answer some of those questions?
Helpful Web Sites
EPA Office of Children's Health Protection (http://www.epa.gov/children/)
Provides information about a child's environment (indoor and outdoor air pollution; drinking water standards; as well as environmental food risks) and potential health issues (asthma and respiratory illnesses; developmental and neurological problems; and childhood cancer).
Children's Health: Environmental Health (http://www.medem.com/MedLB/articleslb.cfm?sub_cat=29)
Includes information about common household environmental dangers, inhalants, and toxic gases.
Environmental Health Issues(http://kidshealth.org/parent/firstaid_safe/home/environ.html)
Contains information about what can be done for such environmental hazards as asbestos; water contaminants such as fluoride, volatile organics (like benzene and carbon tetrachloride), bacteria and viruses, inorganics (such as mercury and nitrates); lead; pesticides; and more.
Assessment Recommendationscompleteness on their final written assignment.
Students may be assessed through their:
a) Consider the history of lead exposure. Introduce students to the topic by showing the section of the program that looks at Dr. Herbert Needleman's groundbreaking research on how lead affects children. (Begin at about 34:00 with "Scientists know from experience just how long and hard the struggle can be·" End at about 41:00 with Dr. Needleman saying, "·So I can't say there's a safe level.")
Have students research and report on when and how lead was found to be unsafe and at what levels. Report on how the government and industry responded to these findings. Summarize current research on lead level safety. What have researchers found? What lead blood level is considered safe? What questions remain? For additional information on lead in the environment, see AMERICAN SCIENTIST:
b) Choose a synthetic chemical and investigate its molecular properties. Have students choose one of the chemicals they identified during their day and research how the chemical is made up on a molecular level. What are the percentages of different elements present in the chemical? How is the chemical molecularly bonded?
c) Have students consider some of the careers associated with environmental health. Students can visit the following Web sites to learn about just a few of the many careers in this field:
Toxicologists study the harmful effects of drugs, environmental contaminants, and naturally occurring substances found in food, water, air and soil. Information about what toxicologists do and where they work can be found at
In this growing field, researchers work to identify the possible causes of many teratogenic agents (substances that can harm a fetus during pregnancy). For information about some typical job opportunities available in the public and private sector, can be found at
Students can also learn more about the scientists featured in KIDS AND CHEMICALS at http://www.pbs.org/now/science/doctors.html.