Chemical PesticidesChemical Pesticides

An Ecological DisasterAn Ecological DisasterBy Virginia Chu & Diana YounBy Virginia Chu & Diana Youn

What is a chemical pesticide?What is a chemical pesticide?

• A chemical pesticide is a chemical substance used to control, kill, or repel pests such as weeds, insects, and other pests.

- About one billion pounds of pesticides are used in the U.S. alone each year.

- Pesticides include herbicides, insecticides, rodenticides, fungicides, and bactericides.

Chlorinated Hydrocarbons & Organic Chlorinated Hydrocarbons & Organic PhosphatesPhosphates

• DDT (dichloro-diphenyl-trichloro-ethane)

• Chlordane• Heptachlor• Dieldrin• Aldrin• Endrin

• Malathion• Parathion• Trichlorfon• Mevinphos• Dimethoate • Diazinon• Dichlorvos

DDTDDT• In 1939, Paul Muller discovered DDT as an effective

pesticide.• An intake of 1/10 of 1 ppm of DDT results in storage of

10-15 ppm (100 x).- Only 5 ppm of DDT can disintegrate liver cells; only 3

ppm can inhibit an essential enzyme in the heart muscle.

- DDT residues have been found in human breast milk. This means the baby receives the chemical and it builds up in the body.

Carbon 14, Hydrogen 9, Chlorine 5

(C14H9Cl5)

Advantages of Using PesticidesAdvantages of Using Pesticides• Increased food

production• Reduction of insect-

borne disease (e.g. used to kill mosquitoes that carry West-Nile virus and malaria)

• Protect pet dogs from fleas.

•

• Controls invasive weeds that could cause environmental damage

• Manages unwanted pests in grocery stores, food storage facilities, gardens, and homes.

•.•.

Disadvantages of Using PesticidesDisadvantages of Using Pesticides

• Pesticides are a serious threat to biodiversity among organisms.

• Pesticides in soil hinder nitrogen fixation by interfering with chemical signaling.

• Pesticide runoff in water contaminates our drinking water and harms organisms living in aquatic environments.

• Pests, bacteria, and weeds may become resistant to pesticides, thus creating “superbugs”.

Health Effects due to Exposure to Health Effects due to Exposure to PesticidesPesticides

• Headaches• Nausea• Respiratory problems• Cancer• Birth defects• Leukemia• Abdominal pain• Neurological deficits

• Miscarriages• Dermatological

conditions• Memory disorders• Dizziness• Vomiting• Skin and eye

problems• Infertility

Water Pollution by PesticidesWater Pollution by Pesticides

• Pesticide runoff into lakes, rivers, and streams can kill the fishes and other organisms in them.

- In one case, even after passing through a purifying plant and 15 streams, the pesticide toxaphene killed all the fish in the streams.

- Pesticide runoff can contaminate groundwater, which in turn contaminates rivers, lakes, and streams.

- A study done by the U.S. Wildlife Service in 1960 discovered that fish stored pesticides in their tissues.

• When a pesticide treatment of 1/50 ppm of DDD was applied in 1954 to Clear Lake, California and reapplied in 1957, birds given the name “swan grebe” died in large numbers. Even though a small amount of the pesticide was applied to the lake, there were heavy concentrations found in the dead birds. This is due to the increasing amounts of the pesticide that is passed on to the larger consumers.

Pesticide Effects on SoilPesticide Effects on Soil

• Nitrification oxidizes ammonia into nitrates so plants can utilize it. The herbicides 2,4-D, BHC, aldrin, lindane, heptachlor, and DDD interrupt nitrification by preventing nitrogen-fixing bacteria from forming root nodules.

• The soil and living things in it mutually benefit and are interdependent on one another.

• Pesticides not only contaminate the soil but they are introduced into plant tissues. Any fruits and vegetables that humans eat then transfers the poison into our bodies.

• Pesticides are persistent in soil long after it has been applied. (e.g. There are still traces of DDT in organisms, rivers, and plants, even though it has been banned since 1972.)

Blanket spraying of pesticides on a Blanket spraying of pesticides on a fieldfield

Changes in the Use of PesticidesChanges in the Use of Pesticides

• 1962- In “Silent Spring”, Rachel Carson condemns the use of pesticides, launching the environmental movement.

• May 15, 1963- The president’s science advisory committee report, “The Use of Pesticides”, called for a decrease use of toxic chemicals in the environment.

• December 2, 1970- Environmental Protection Agency (EPA) created.

• June 14, 1972- Banning of the use of DDT• 1972- The Federal Insecticide, Fungicide, and Rodenticide Act

(FIFRA) was revised for better regulation of pesticide usage to better protect applicators, consumers, and the environment.

Benefits of Biological PesticidesBenefits of Biological Pesticides

• Controls plant diseases, insects, and weeds.• Biodegrades in soil easily, unlike chemical

pesticides that persist over long periods of time.• They’re non-toxic and non-lethal so that they

are, relatively, environmentally friendly.• Selectively targets pests so that other possibly

beneficial insects won’t be exterminated.

What is a Biological Pesticide?What is a Biological Pesticide?

• A chemical derived from living organisms that can be used for pest control.

• Microorganisms-- such as bacteria, fungi, viruses, etc.– that are can be for pest control.

• Chemicals that are naturally occurring, like pheromones and enzymes, that can be used for pest control.

B. subtilisB. subtilis• A biological pesticide that is capable of suppressing up to 30 different

pathogens.• Produces 2,3-DHBG (2,3-dihydroxybenzoylglycine). This iron-

chelating agent deprives plant pathogens of iron, resulting in poorly functioning pathogens.

• Produces proteases that actively attack pathogens’ cell walls.

Insect PheromonesInsect Pheromones

• Can disrupt the reproductive cycles of harmful pests.

• Can lure pests into traps, allowing farmers to monitor them and determine how much pesticide to use.

• Do not harm other animals.

Accessible Biological PesticidesAccessible Biological Pesticides

• Avid• Azatin E.C.• Citation• Enstar II• Gnatrol • M-Pede • Mycostop • Hot Pepper

Wax

CitationsCitations• Pesticides in the Nation’s Streams & Ground Water, 1992-2001

http://pubs.usgs.gov/circ/2005/1291/pdf/circ1291.pdf • Development of New Chemical Pesticides

http://www.res.titech.ac.jp/~junkan/english/pesticide/index.html • U.S. Environmental Protection Agency http://www.epa.gov/pesticides/glossary/• Biological Pesticides http://www.agnr.umd.edu/users/cmrec/97-1nmn8.htm • American Psychological Association (APA):

Pesticide.http://www.reference.com/browse/wiki/Pesticide

• Chicago Manual Style (CMS): Pesticide. http://www.reference.com/browse/wiki/Pesticide

• Modern Language Association (MLA): "Pesticide." http://www.reference.com/browse/wiki/Pesticide\

• Insect Pheromones: Master in Communications to Control Pests http://www.beyonddiscovery.org/content/view.article.asp?a=2702

• Biopesticides- A Safe Alternative to Pesticides http://www.panda.org/news_facts/education/high_school/homework_help/webfieldtrips/biopesticides/index.cfm