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Toxic Substances and Trash in Our Environment

  • LEVEL: GRADES 6 - 8


Illustrate the relationship between human well-being, environmentalism and the interests of animals.


This unit will provide information concerning toxic substances and trash in our environment. Students will learn about the effects of pesticides, acid rain, PCBs and trash on wildlife and people.


"To understand biology is to understand that all life is linked to the earth from which it came; it is to understand (that) the stream of life, flowing out of the dim past into the uncertain future, is, in reality, a unified force."

Rachel Carson

"Humane Biology Projects"

Endangered Species Handbook (1990)

Information has been discovered in the last decades warning of the dangers we face from the toxic chemicals in our environment, such as pesticides, acid rain and PCBs as well as from trash and debris. The public health danger may be irreversible and irreparable - deadly contamination of our air, water, soil and the plants and animals that make up the food chain. In response to this critical problem, federal, state and local governments have responded with regulations. These regulations are designed to safeguard our environment and the plants and animals that are an integral part of it and, in doing so, safeguard human health and lives. While these regulations can be improved, they have helped to clean up lakes, rivers, air and the land.

In industrial nations like the United States, alarming evidence has come to light in recent years that has shown a direct association between widespread chemical contamination of our environment and numerous human deaths and disabilities. Among the major sources of exposure are certain industrial processes in the manufacture of pesticides and the pesticides themselves.

For example, let us look at the dangers posed to the environment and the public by the tens of thousands of chemical plants located across our country. Experts in the chemical industry estimate that at least 50,000 chemical processing plants around our country alone have design defects that could allow leaks of cancer-causing and toxic chemicals. On August 11, 1985, a Union Carbide plant in Institute, West Virginia released a cloud of cancer-causing chemical containing a derivative of MIC*, sending

more that 135 workers and residents to hospitals and trapping thousands more indoors until fumes dissipated. Routine emissions of such toxic chemicals had been occurring at the plant for years, causing a higher rate of cancer and other illnesses in the area with every passing year.

* MIC + methyl isocyanate

Dramatic wildlife losses were soon apparent. Thousands of song birds died and massive fish kills were reported. Birds at the top of the food chain: hawks, eagles and other fish-and-meat-eating species declined dramatically, many to the point of extinction and near extinction. Bats, butterflies and other animals feeding the sprayed areas, as well as tropical wildlife and many animals in the ocean food chain also succumbed to these toxic chemicals. The side effect of these toxins was an interference with animal reproduction -- pernicious defects in offspring and sometimes sterility.

Acid Rain

Acid Rain is formed when oxides of sulfur and nitrogen, created from the burning of fossil fuels - coal, oil and gas - are released into the atmosphere, where they react with other substances in the air to form sulfuric and nitric acids. Rain and snow become contaminated by these acids and therefore, the name "acid rain."

Acid rain is very toxic and eliminates numerous life forms where it falls. In Europe and North America, tons of oxides are spewed into the atmosphere each year, killing numerous species of freshwater animals. Gradually, all life forms are killed in lakes and streams. This phenomenon, which began in the 1920's, left

thousands of lifeless lakes in its path. All life that was able to live and reproduce there -- fish, invertebrates, microscopic plankton and higher plants -- were killed by exposure to acid rain. The effects of acid rain spread to surrounding life. Tree deaths have become epidemic. Lichens and spotted salamanders are two of the life forms that rapidly disappear in areas of acid rain.

Success Stories: The outlawing of lead in gasoline in the early 1970's has greatly reduced its presence in surface and groundwater, air, the land and in our homes. Use of DDT was outlawed in the United States in the early 1970's. This allowed for the comeback of the bald eagle and the peregrine falcon. DDT has the harmful effect of thinning their eggshells making it impossible for any chicks to hatch.


PCBs, or polychlorinated biphenyls, are chemicals which were used in refrigeration, insulation and related systems. They are not biodegradable and posed ominous threats to all wildlife.

Scientists found that PCBs caused harmful effects in mammals, which are particularly susceptible to them. These effects have included: changed genes resulting in birth defects, reduced fertility, disruption of normal behavior patterns and abnormal behavior in mammal mothers. These chemical s have caused cancer and death to both animals and humans. The manufacture of PCBs was banned in the United States, in the 1970s but they had, nevertheless, already become pervasive in the environment.

Marine Debris

In addition to toxic substances, trash left on beaches and in waterways can have serious impacts on wildlife, the environment and our economy. Litter discarded inland can be carried by streams, rivers or sewers into the ocean. Thousands of marine mammals are caught in and strangled by debris annually. Coastal communities must spend thousands of dollars when littered beaches must be closed or cleaned. Marine vessels are sometimes damaged by the debris as well.

The two primary problems that marine debris poses to wildlife are entanglement and ingestion. Entanglement can cause wounds that lead to infections and/or loss of limbs. It can impair an animal's ability to swim causing drowning, inability to escape predators or inability to find food. It can also cause strangulation and suffocation. Animals may feed on debris because it looks like food. Ingested items can block the intestinal tract and prevent digestion thereby leading to starvation. Ingested items can also block air passages and prevent breathing.

Marine debris can also impact upon humans. It is visually unpleasant and must be removed before it threatens the loss of tourist dollars. Marine debris can also endanger the safety and health of humans. Sharp objects such as rusty metal or broken glass can cause injuries when people inadvertently step on them. Contaminated debris, such as sewage and medical wastes, may pose a human health hazard though transmission of diseases. In the summers of 1987 and 1988, for example, medical wastes including needles and bandages from hospitals, washed up on the shores on New York and New Jersey beaches. Local officials had to close the beaches and vacationers went elsewhere while the cleanup was in progress.


Students will conduct research and gather information on toxic substances and marine debris and their relationship to environmental health, as well as human and animal well-being.

Pesticides and Herbicides

A pesticide is defined as a substance for destroying harmful insects. A herbicide is defined as a substance that is poisonous to plants which is used to destroy unwanted vegetation.

When pesticides (including DDT) and herbicides were developed in the 1940's they were considered of tremendous benefit to humans. Spraying of swamps to control malaria began on a large scale, first in America, then worldwide. Farmers and home gardeners began using the chemical DDT to spray fields, vegetables and fruit trees to kill insect pests. However, by the late 1940's, the lethal effects of these chemicals on our environment and our wildlife became apparent. chemists began to piece the puzzle together: pesticides of the chlorinated hydrocarbon family, such as heptachlor and endrin, had pervasive and lethal effects throughout our environment. Contamination of air, water, soil, plants and animals were widespread and cumulative, poisoning our life-support system and killing some of the earth's most beautiful and delicate plants and animals. Because the DDT family of pesticides does not break down into component parts when released into the environment, it is stored for years in increasing lethal amounts in the tissues of plants and animals. Plants and animals that were an integral part of our food chain were now accumulating increasing amounts of toxicity. The use of DDT has been banned in the United States since the 1970s.

Toxic Wastes

Every year the United States generates millions of dollars of tons of toxic wastes. These hazardous waste materials present a major environmental and public health problem. Many hazardous wastes are disposed of in a safe, legal and acceptable way. Some wastes, however, are dumped illegally or disposed of in a manner that poses a tremendous threat to the health of our natural environment, food chain, wildlife and humans. Some of these wastes are known to cause cancer, birth defects and other disorders. One infamous example is the health disaster caused by the toxic dumpsites around the Love Canal area of Niagara Falls in New York State. After 30 years, the chemicals dumped in that area were still toxic enough to cause a vast number of problems typical of toxic waste pollution.

Hazardous waste results when a company such as a chemical company, a computer manufacturing company, or a dry cleaner generates a waste product. Before the company discards this waste, they must determine whether or not the waste is hazardous using the standards of the Resource Conservation and Recovery Act (RCRA) which was passed by Congress in 1976. RCRA has been effective in compelling companies to manage their hazardous wastes safely, in order to protect human health and the environment. However, certain problems still exist with this law. There is a loophole which makes it possible for a company which recycles hazardous waste which are called heavy metals ( e.g. lead, cadmium, silver) to allow some of it to windup in animal feed. Hopefully, citizen protest may help to change this law for the better.

Contaminating the Water

The President's Council on Environmental Quality (CEQ) stated, in 1981, that many tasteless and odorless chemicals present in our drinking water supply can cause health problems. Other governmental reports at this time have catalogued the damage to both our surface water and our ground water and found that the contamination of both by toxic chemicals, e.g. PCBs, DDT, mercury and asbestos, is both substantial and long-term. There is concern that, decades from now, we may find that the polluted water has soaked through permeable soil s today will replenish our already polluted surface water in lakes and streams. This same ground water supplies over 40 percent of water used for agricultural and irrigation purposes.

Air Pollution

Air pollution remains a serious problem, a major aspect of which is the presence of dozens of chemicals and other pollutants. It has been documented that air pollution is causing serious health problems for millions of urban residents. Although some clean air laws have been passed and others -- based on EPA research -- have been proposed, high levels of industrial pollution go unregulated. Air pollution continues to contribute to health problems including increased asthma attacks, lung disease, chronic bronchitis and increased susceptibility to viral diseases of the respiratory tract.

Clean Air Act regulations have brought about improvements. Most types of motor vehicles must meet high standards controlling the amount of air pollution they emit. However, the vast number of cars used by people world-wide still caused air pollution. In addition, sport utility vehicles are exempt of the high air standards in an attempt to improve the ailing United States auto industry.

Marine Debris

Prevention is an important way to stop marine debris. The United States and other countries, private organizations and individuals are working to prevent debris from causing problems on beaches and waterways. In the United States, federal, state and local legislation has been passed banning harmful plastic items, encouraging recycling and addressing ocean disposal. MARPOL Annex V is the first international legislation to regulate the disposal of garbage at sea.


  1. Conduct research on the disappearance of the western grebe from Clear Lake, California.
  2. Conduct research on the impaired reproduction and disappearance of the peregrine falcon from its natural habitats, including the Hudson River area in New York State. Also research the attempts to bring back the population.
  3. Conduct research on the bald eagle, another bird whose numbers have been reduced by pesticides and who have been bred in captivity for release.
  4. Undertake a research project on:
    • the osprey
    • the hermit ibis
    • the brown pelican
    • bats
    • butterflies
  5. Research the use of DDT and other pesticides in developing countries and their devastating effects on migratory birds.
  6. Research the effects of debris on marine life. What types of debris are harmful to seagulls, other birds sea turtles, seals, fish? to marine animals overall? to humans? to the environment?
  7. What is the least harmful? How has federal, state and local legislation helped? How does the Center for Marine Conservation help?


The following two projects won humane science awards at the New York City Science Academy's Science Fair in 1991 and 1992 respectively.

Example #1: Graphical Analysis of Agent Orange Exposure Data

Student: Andrew Stellman, Grade 12, La Guardia High School of the Arts, Manhattan

Project: Graphical Analysis of Agent Orange Exposure Data. To encompass research and to create computer graphics of Agent Orange that are readable, and that link information on where and when spraying occurred to the location of American troops. (Existing graphs are not readable, nor do existing studies link spraying to troop movements.) Graphical analysis makes existing data clearer. The readability is the ease of comprehension of the analysis.

In the Vietnam War, 19 million gallons of herbicides were sprayed over forests and crops of Vietnam, to deprive the enemy of cover during warfare and of the crops they needed to survive. the phenoxy herbicides used in Agent Orange are harmful to animals and people.

Materials and methods used in the project: Spray Database containing records of all herbicide spraying (National Academy of Sciences tape and Army and Joint Services Environmental Support Group tape.)

The Universal Transverse Mercator (UTM) coordinate system. A standard system for representing map coordinates.

Troop Movement database including a huge number of troop movements, compiled from the Center for Disease Control "Battalion Tape" and the Veteran Administration Mortality Study.

Several computerized tools were used:

  • Computer: digital Equipment VAX 11/780 mainframe
  • Computer: Northgate 386/20 Slimline Series
  • FORTRAN-77 programming language, VAX extension (VAX) (Digital Equipment Corporation, 1989)
  • SPSS-X Statistical Analysis System (VAX) (SPSS, INC. 1987)
  • Plot-It graphical software (northgate) (scientific programming enterprises, 1987)

Analyses are presented for individual months, within individual UTM coordinate grids (100 km by 100 km); UTM grid XT.

Gathering the data:

Using computer technology, useful data were extracted from the Spray Database and the Troop Movement Database. A Spray Density Index was created. Data on overlaps between spaying and troop movements were created. New files were thus created.

Graphs produced in this project are far more readable than existing graphs. They contain several reference points to put the map in perspective. They also contain exact visual representation of complex information, which readily lends itself to interpretation.

Example of graphs:

  • Plot of herbicide spray locations and density
  • plot of troop movement and herbicide spray locations
  • Plot of troop movement and herbicide spray overlap locations


There have been no pervious graphs of troop movement and herbicide spraying plotted comparatively. This representation demonstrates conclusively the overlap of spraying and troop location, a great point of contention for years. It is no longer possible to argue whether or not troops have been sprayed.

data also provides the opportunity for future projects to study health effects of herbicides praying, by identifying and following individual military units, or location or time ranges.

Graphical analysis of the Agent Orange exposure data has proved conclusive. Data was made more manageable and more readable.

Example #2: Water Pollution on Staten Island

Student: Marc Loeb, Grade 9, Tottenville High School, Staten Island

Project: Water Pollution on Staten Island. To determine whether or not the water on Staten Island was polluted, and if so, to determine how and when the water was polluted. Water samples were collected from Clove Lake, Wolf's Pond, Richmond Creek and natural spring water was used as a control.

Four scientific tests for water pollution were conducted on the water samples:

  1. RELATIVE STABILITY. This measures the amount of combined and free oxygen dissolved in water. Microscopic bacteria, plants and animals need oxygen for life. The faster many forms of bacteria grow, the more oxygen they need. Waste products, emptied into waterways, often provide vast food supplies for bacteria that are living there. This over-abundance causes bacteria and many other forms of small organisms to grow faster than the amount of dissolved oxygen will allow.

    When this happens, all of the aquatic life will die. This will result in massive fish kills.Fish killed in this manner further aggravate the problem by providing additional food supplies to the already over-fed aquatic population. This "Domino Effect" severely upsets the ecology of that particular body of water.
  2. CHLORIDE. High concentrations of chloride make water unsuitable for industrial, agricultural and recreational use. The history of many arid regions of the world has been strongly influenced by chloride concentrations, i.e. areas where extensive irrigation systems draw water from the rivers of the region, such as the Nile or the Colorado rivers.
  3. PHOSPHATE. Phosphates are chemical compounds necessary to all living things. However, an excess of phosphates in water can cause serious pollution problems. Sources of phosphates are varied, including industrial waste, sewage, agricultural waste and ordinary household detergents. Excess phosphates stimulate growth of algae, which depletes the water of its dissolved oxygen, thereby suffocating other life forms such as fish. The control of phosphate pollution is an important step in the preservation of wildlife that is dependent upon our natural waters.
  4. PH. Ph is the measure of acidity or alkalinity of a substance. Ph is measured on a scale of 0 to 14 and the midpoint 7 is considered neutral. Substances greater than 7 are acidic. If a substance is either highly acidic or highly basic it may be very dangerous, in that it destroys materials by caustic action.

    A very strong acid or base in large volume is usually the result of man-made pollution. Contamination can be from industrial or agricultural sources, refinement of ores, production of chemical or other substances, mining or runoff fields where fertilizers and other chemicals have been used.


  1. Water collected farthest from the landfill will be ore stable than water collected closest to the landfill.
  2. Concentration of chloride will be highest in water collected closest to the landfill.
  3. Water from Wolf's Pond will have the highest phosphate level because houses in close proximity release washing machine water in the area around the pond.
  4. Water closest to the landfill will have a lower pH, making it more acidic.


All hypotheses were confirmed. The results of the tests proved that the water from Richmond Creek, which is closest to the landfill, was the most polluted water from the samples.


  • Abbott, Warren. "Butterfly population declines due to insecticides," Christian Science Monitor, Jan. 20, 1982, p. 16
  • Brewer, Jo. "How to Kill a Butterfly," Audubon, March 1992, 74(2):76-88.
  • Carson, Rachel, Silent Spring, Houghton Mifflin, Boston, 1970.
  • Council on Environmental Quality. The Global 2000 Report to the President. The Technical Report, 1980, Vol. II
  • Environmental Protection Agency, Puzzled About Recycling's Value? Look Beyond the Bin, EPA. January 1998
  • Environmental Protection Agency, Science Demonstration Projects in Drinking Water (Grades K - 12), EPA, 1990
  • Environmental Protection Agency, Turning the Tide on Trash - A Learning Guide on Marine Debris, EPA, 1992
  • Nilsson, Greta, The Endangered Species Handbook, Animal Welfare Institute, USA, 1983. Reprinted 1990.
  • Regenstein, Lewis, How to Survive in America the Poisoned, Acropolis Books, Washington, DC 1986.
  • North America Association for Environmental Education (NAAEE) Environmental Education Materials: Guidelines For Excellence, Naaee, 1996