Earth Tones, a Canadian science program, covered the history of DDT control.
[Below the fold, because it plays automatically. Grrrr.]
Earthtones is a television series focusing on environmental science taking place at Agriculture and Agri-Food Canada, Environment Canada, Fisheries and Oceans Canada, Natural Resources Canada and Health Canada. The series aired on the Discovery Channel’s @ discovery.ca between 1998 and 2001.
Below, a teachers’ guide on how to use this video in the classroom, from Science.gc.CA.
DDT (Dichloro-diphenyl-trichloroethane) – Teacher’s Guide
Find out why DDT was banned in 1972, and why this decision was one of the most important steps in protecting wildlife and people from the effects of pesticides.
Science/Environmental Studies (Grade 7/8)
- Demonstrate an understanding of the effects of human activities and technological innovations on the sustainability of ecosystems;
- Explain the long-term effects of the extinction of species;
- Identify and explain economic, environmental and social factors that should be considered in the management and preservation of habitats.
Science/Environmental Studies (Grade 9/10)
- Identify and evaluate Canadian initiatives in protecting Canada’s ecosystems;
- Explain changes in popular views about the sustainability of ecosystems and humans’ responsibility in preserving them;
- Explain the process of bioaccumulation and assess its potential impact on the variability and diversity of consumers at all trophic levels.
Environmental Studies/Geography (Grade 11/12)
- Describe a generalized food web;
- Explain how human use of toxic substances contaminates the food web;
- Describe the properties of chemical fertilizers and pesticides and their use in agriculture;
- Explain the concept of stewardship and how it relates to the sustainability of resources;
- Explain the rights and responsibilities of citizens and consumers with respect to the environment and sustainable resource management.
You Should Know…
Pests are capable of causing tremendous damage to both crops and livestock. When pest populations rise to an unacceptable level, pests need to be controlled to enable farmers to effectively and efficiently produce agricultural products of good quality that can be competitively priced. Farmers use a variety of methods to manage pests. Pesticides are one of the methods of managing pests. Increasingly, pesticides are being used in combination with other pest management techniques in an integrated pest management strategy.
Both federal and provincial governments strictly regulate the use of pesticides. Since pesticides have the potential to harm the environment, people and other animals, they must be used according to strict safety guidelines. Pesticide safety practices vary, depending on the potential hazard associated with the pesticide being used and the application method. Safety guidelines apply from the time the pesticide is purchased until the disposal of the empty containers or unwanted chemicals.
Canadian farmers use far less pesticides than do their counterparts in Europe and the United States… and the amounts are in decline! In Canada, in 1975, the use of pesticides was 75 kilograms per hectare. The amount rose for a few years, but in recent years has dropped to 64 kg/ha. Comparable 1995 figures for other countries are as follows: United States 238 kg/ha, Germany 250 kg/ha, and France 432 kg/ha.
- The focus of this video is DDT. What is it? Why was it used? When was it used? How much was used?
- How did DDT affect birds?
- Chip Weseloh notes in the video that the birds at the top of the food chain were more affected by DDT. Explain how this is the case, with references to the concept of bioaccumulation or biomagnification.
- What is a “persistent” chemical? In the case of DDT, how long does it last?
- DDT was banned in 1969, over 30 years ago. What affect did this have on the environment?
- This is a “good news” story. Why?
- Explain how bioaccumulation works, using the food chain as an example.
- One of the birds mentioned in the video is the peregrine falcon. Why did DDT affect it? What have been the recent advances in the “return” of the peregrine falcon?
- Research to determine the definition and examples of the following terms: extinct; critically endangered; endangered; vulnerable
- Provide a Canadian example of each of the terms. Research to determine the CAUSE of the precarious state of the example (e.g., urban encroachment, pesticide use…)
- Define the terms “pest”, “pesticide”, and “integrated pest management”.
- What changes in technology have taken place in the past few years that make the use of pesticides in agriculture more effective, efficient, and less damaging to the environment?
- Research into the Passenger Pigeon, once the most prolific bird in North America… and now extinct. Although not related to pesticide use, the extinction is related to human activity and the environment. Would this have happened in the 21st century? Why or why not?
Assessment and Evaluation
Use a creative controversy model to evaluate the use of pesticides in agriculture. The class is divided into groups of four students. Two students take one side of the issue, and two students take the opposite side. Students research the issue, present arguments for… or against… the issue, and counter the arguments of the other side. This is all done in small groups of four, two students on each side of the argument. Then, students “switch” sides and do the same for the other side of the argument. This way, they get to experience both sides of the argument.
Following the presentations by all groups (to each other) a general discussion takes place to examine the information that has been brought forth by all groups.
Then, each student prepares a one-page report on the issue, taking either side, or developing a compromise position.
More, Resources and related articles (with help from Zemanta)
- DDT Discharge Still Polluting SF Bay Near Richmond Despite Clean Up Efforts (sanfrancisco.cbslocal.com)
- Excessive use of DDT in mid-1900s (aml24101614.wordpress.com)