AP Environmental Science: The Pesticide Dilemma
Name: _____
References: Wright, Environmental Science, chapter 13
Raven, The Environment
http://on.aol.ca/video/pesticide-poisoning-in-rural-cambodia-502318605
Key Terms and Vocabulary:
Pest, weeds, vectors, herbicides, pesticides, chemical treatment, ecological pest control, integrated pest
management (IPM), endocrine disruptors, bioaccumulation, biomagnification, resurgence, pesticide
treadmill, synergistic effect, cultural control, natural enemies, genetic control, natural chemical control,
hormones, pheromones, economic threshold, insurance spraying, cosmetic spraying, field scouts, organic
food, Organic Foods Protection Act, microbial, plant-incorporated protectants, Delaney clause, Food
Quality Protection Act (FQPA), prior informed consent (PIC).
Different philosophies of pest control
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Chemical treatment of pests: eradicates or decreases pest numbers
Gives only short-term protection
Has highly damaging side effects to other organisms
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Ecological control: long-lasting protection
Based on knowledge of the pest’s life cycle and ecological relationships
May be other organisms or chemicals
May be highly specific to one organism
May manipulate some aspect of the ecosystem
A. Definitions
How are pests defined? Examine the pests on page 319 Fig 13-1 (slide 4)
How are pesticides defined?
What are vectors?
What are Biofouling organisms?
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What are Herbicides?
Where have you seen the use of herbicides on or near the Morven campus?
What are Insecticides?
What pest has drastically affected Canadian and North American forestry? (chapter 7)
The emerald ash borer threatens 7.5 billion U.S. trees
What are Fungicides? Give examples of where these are used. Page 318
What are rodenticides
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A. What are Broad- and narrow-spectrum pesticides?
Narrow-spectrum pesticides kill only the organism for which it was intended
and do not harm any other species
Most pesticides are broad-spectrum pesticides, do not degrade readily and/or
break down into compounds as dangerous as or more dangerous than the
original pesticide
B. What are First- and second-generation pesticides? page 322
Pre 1940s, pesticides were either inorganic (contained lead, mercury,
and arsenic) or organic compounds (botanicals and synthetic
botanicals)
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You must be able to differentiate between botanical pesticides and
synthetics!
B. Major groups of insecticides
1. Chlorinated hydrocarbons were widely used from the1940s
until the 1960s when most were banned
a. Examples include DDT (to be discussed in detail later),
endosulfan, lidane, and methoxychlor
b. Synthetic, broad-spectrum insecticides
c. Slow to degrade
d. Persist in the environment and in organisms
2. Organophosphates contain phosphorus and have generally
replaced chlorinated hydrocarbons in large-scale agricultural
use
a. Examples include methamidophos, dimethoate, and
malathion
b. More poisonous than other types of insecticides
c. Highly toxic to terrestrial and aquatic organisms
d. They do not persist in the environment for as long as
chlorinated hydrocarbons
3. Carbamates are derived from carbamic acid
a. Examples include carbaryl and aldicarb
b. Broad-spectrum insecticides
c. Generally not as toxic to mammals
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C. Major groups of herbicides
They tend to be grouped according to how they act and what they kill
1. Selective herbicides kill only certain types of plants
a. Broad-leaf herbicides kill plants with broad leaves but
do not kill grasses
b. Grass herbicides kill grasses but are safe for most other
plants
2. Nonselective herbicides kill all vegetation
D. Inorganic pesticides such as arsenic, copper, mercury and lead are highly
toxic and persistent.
E. Botanical Pesticides such as pyrethrum which is extracted from
chrysanthemum flowers.
Provide some information on DDT. Page 322 onwards and other.
http://www.youtube.com/watch?v=Ipbc-6IvMQI Pesticides DDT Rachel Carson - Silent
Spring.
http://www.youtube.com/watch?v=-UiCSvQvVys DDT let’s put it everywhere 1946
http://www.youtube.com/watch?v=gtcXXbuR244 DDT so safe you can eat it.
Irony in all of these videos.
Dichlorodiphenyltrichloroethane
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Pesticide use in the US. Examine Fig 13-4 page 321Read about the Pesticide
Expense. Page 320.
II. Benefits and costs of using pesticides
A. Benefits of pesticides
1. Disease control
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2. Crop protection _________
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B. Problems associated with using pesticides
1. Development of resistance by pests
Refer to page 317 bedbugs and 326 to 327
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2. Imbalances in the ecosystem – “Balance of nature”
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Pesticides kill organisms other than the ones they are meant for. eg.
Small species.
This is typical of broad insecticides like Dieldrin. (banned)
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The stress of having the pesticide in the animal’s body may also
make it more vulnerable
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Natural enemies of pests
starve or migrate in
search of food and so
these animals reduce in
number.
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New pests take over. e.g. Scale insects on lemon trees when DDT
was used to kill insect pests which prey on the scale insect.
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Resurgence: occurs after a pest has almost been eliminated
o The population recovers and even explodes
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Secondary pest outbreak: insects that were originally of no concern
explode and create new problems
o They quickly become resistant to pesticides
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Pesticide treadmill: use of pesticides increases resistance and
secondary-pest outbreaks
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3. Persistence, Bioaccumulation, and Biological Magnification

These are all typical of DDT which is a chlorinated hydrocarbon.
Chlorinated hydrocarbons are very stable and breakdown very
slowly (persistence).
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Bioaccumulation is
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Biological magnification is
Refer to page 326 and to Fig 13-8
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Fig. 23.9 Biological magnification of DDT in a Long Island Salt Marsh.
What are the problems with nonpersistent pesticides?
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Comment on synergism page 328
4. Mobility in the environment
Pesticides move through the soil, water and air.
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Risks to human health
Refer to table 13-1 and page 324 to 325
Short-term effects = nausea, vomiting and headaches, abdominal pain, shock,
respiratory failure, allergic reactions, seizures, pneumonia, coma
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About 39 million people/yr suffer acute poisoning
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Most acute cases occur in developing countries
Untrained users have little information on pesticides Fig 13.6
People get sprayed, incorrectly store pesticides, or drink water from contaminated
containers
Chronic health problems
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Pesticides may cause:
Pesticides as Endocrine Disruptors.
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The Use of Herbicides in warfare.
http://worldfocus.org/blog/2009/01/15/agent-orange-devastates-generations-ofvietnamese/3625/ Agent Orange - Dioxin
Bhopal Disaster in India – gas escape from pesticide plant in Bhopal
http://on.aol.ca/video/the-bhopal-gas-tragedy-119994557
C. Solutions to the Pesticide Dilemma 13.3 page 329
Alternative pest control methods
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Ecological control: What is this?
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Refer to fig 13-11
Four categories of ecological pest control can be:
Cultural control, natural enemies, genetic control, and natural chemical control
Differentiate between these.
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Biotechnology and Bacillus thuringiensis page 333
4. Natural chemical control - Pheromones and hormones
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6. Integrated pest management (IPM)
What is this?
Involves a combination of pest control strategies – chemical and nonchemical – that are unique to the crop and the location.
Non chemical involve the use of natural predators, the use of sex
pheromones to attract bugs to a place
away from the crops, the introduction
of sterile breeding partners and crop
rotation.
If chemical products are used they are
used on specific targets reduce their
use.
Would you buy rice from Indonesia? Explain your reasoning. Page 336
Irradiating foods
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Organically grown food
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Many farmers are turning away from pesticides, chemical fertilizers, antibiotics,
and hormones
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II. Legislation and international issues
Three agencies are involved in protecting consumers from pesticides on food:
A. EPA: sets allowable tolerances for residues
B. FDA: monitors and enforces tolerances on most foods
C. Food Safety and Inspection Service (USDA): monitors and enforces
tolerances on meat, poultry, and eggs
A. U.S. Federal pesticide legislation
1. Food, Drug, and Cosmetics Act, FDCA.
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2. Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA, 1947) page
338 _
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3. Food Quality Protection Act (FQPA) page 339
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4. Plant Protection Act page 338
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5, Organic Food Protection Act 1990 page 337
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Established the National Organic Standards Board (NOSB) under the
USDA
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Standards for certifying organic foods prohibits:
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What does the USDA symbol on food represent?
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What is APHIS?
The EPA adds a 10-fold safety factor in assessing children’s risks from pesticides
Children eat more fruits and vegetables per unit of body weight
They are more susceptible to carcinogens and neurotoxins
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Tolerances: limits set by the EPA on the amounts of a pesticide that can remain in
or on foods
Malathion’s tolerance on crops is 8 ppm
But in milk, it is 0.5 ppm because children drink it
B. Global pesticide issues
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U.S. agencies collaborate with other nations to prevent the spread of pest
organisms
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The International Plant Protection Convention (IPPC)
Set up an international system to quarantine products to prevent pest spread
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The 1995 United Nations Convention on the Law of the Sea (UNCLOS)
Prevents the introduction of marine species to new areas
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The Rotterdam Convention: an international treaty
Promotes open exchange of information about hazardous chemicals between
countries (including pesticides)
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What does POP stand for?
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Look up the “Dirty Dozen” on the table
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What is the Stockholm Convention on Persistent Organic Pollutants?
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What would you include in a persuasive article in the Georgia Strait or
North Shore newspaper in an attempt to encourage people to reduce the
use of pesticides? (5 marks)
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How are Persistant Organic Pesticides, POPs, linked to climate change? Page 320
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In summary
1. With new farming practices in place, food production has increased dramatically, and
with it, the need for pest control has increased dramatically in the past 50–60 years.
Pest control has taken on two basic forms: chemical treatment or integrated pest
management.
2. Use of chemical pesticides, including DDT have simultaneously allowed for higher
food production and for increased pest resistance, human health conditions, and
effects on the broader environment. Recently, we have focused on the use of
synthetic organic chemical pesticides with little resolution to our long standing issues
with pesticides.
3. Ecological control of pests is a way of using natural factors to control pests in such a
way that is not harmful to humans and allows for sustainable agriculture.
4. Agriculture is moving away from pesticides and towards integrated pest management
and organically grown food as consumer concern over pesticides increases.
5. Policies have been put in place that address the effect of pesticides on human health,
the need for proper training for those who work with pesticides, and the need to keep
food free of pesticide residues.
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