Transcript Pesticides - Duluth High School

Pesticides
Pesticides -Pros and Cons
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Kill unwanted pests that
carry disease (rats,
mosquitoes, Tse-Tse flies)
Increase food supplies
More food means food is
less expensive
Effective and fast-acting
Newer pesticides are safer,
more specific
Reduces labor costs on
farms
Food looks better
Agriculture is more
profitable
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Accumulate in food chain
Pests develop resistance –
500 species so far
Resistance creates pesticide
treadmill
Estimates are $5-10 in
damage done for $1 spent
on pesticide
Pesticide runoff
Destroy bees - $200 million
Threaten endangered
species
Affect egg shell of birds
5% actually reach pest
~20,000 human
deaths/year
Types of Pesticides
Biological – Ladybugs, parasitic wasps,
etc.
 Carbamates effect nervous system of
pests more water soluble than
chlorinated hydrocarbons
– Aldicarb, aminocarb, carbaryl
(Sevin), carbofuran, Mirex
 Chlorinated Hydrocarbons affect
nervous system –
– Aldrin, Chlordane, DDT, dieldrin,
kepone and toxaphene
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 Fumigants
are used to sterilize
soil and prevent grain infestation
 Organophosphates – extremely
toxic, rapidly absorbed, low
persistence
– Malathion, parathion
Types of Pesticides
 Inorganic
mercury
– arsenic, copper, lead,
– Highly toxic and bioaccumulation
 Organic
or natural – derived from
plants such as tobacco and
chrysanthemum
Chlorinated Hydrocarbons
(organochlorines)
 DDT,
aldrin, dieldrine, chlordane and
toxaphene
 Affect the nervous system of pest
 Remain in ecosystem 15+ years
 Highly persistent, fat soluble, and
subject to biomagnification
 Nearly all have been banned
Carbamates
 Are
used as insecticides, herbicides and
fungicides
 effect nervous system of pests
 More water soluble than chlorinated
hydrocarbons – which means greater
risks of dissolving in surface water or
percolating into groundwater
 100 grams has the same effect as
2,000 grams chlorinated hydrocarbons
 Examples: Aldicarb(Temik),
aminocarb, carbaryl (Sevin),
carbofuran, Mirex
Aldicarb
Potato growers on eastern Long Island used
Aldicarb from 1975 – 1979 to control the
Colorado potato beetle and the golden
nematode. In 1979, Aldicarb residues were
detected in well water. Subsequent testing
found more than 2,000 wells with very high
concentrations. It was banned in New York.
In 1984 areas with deep wells were found to have
increased levels from 1979 levels. 1400 wells
are still contaminated above state guidelines.
Aldicard has been found in groundwater in 26
other states.
Fumigants
Methyl Bromide was banned in
2005 due to it’s damage to the
ozone layer.
Gaseous pesticides use to
sterilize soil and prevent
pest infestation of stored
grains.
Used on grain weevils,
beetles and moth
catepillars.
Comparable to “mustard
gases” used in WWII.
Phosphine is the most
popular today – others
are carbon tetrachloride
and methyl bromide
Inorganic
Broad-based pesticides.
Includes arsenic, copper, lead,
mercury.
Highly toxic and accumulates in the
environment.
Organic or Natural Pesticides
Natural poisons derived from
plants such as tobacco or
chrysanthemum.
Neem
 Ingredients: Contains 2 ingredients, azadirachtin
(AZA0 and liminoids, both from the seed kernels of
the neem tree fruit.
 Application: Sprayed onto plant leaves.
 How It Works: Upsets the insects hormonal system
and prevents it from developing to its mature stage.
Most effective on immature insects and species that
undergo complete metamorphosis.
 Pros: Non-toxic to humans
 Cons: Washes away in rain. Slow acting. Breaks down
in sunlight Indiscriminate pesticide
 Precautions: Keep pets from treated leaves until
they dry.
Organic Pesticides
Pyrethrins
 Ingredients: Derived from Chrysanthemum
cinerariifolium
 Application: Generally found in powder form
and dusted on leaves.
 How It Works: Poisons the insect, causing a
quick death
 Pros: Quick acting. Low toxicity to animals.
Degrades within a day.
 Cons: Broad spectrum insecticide. Kills any
insect. Very toxic to honeybees
 Precautions: Use cautiously, only when you
have a major problem with hard-to-kill insects.
Organic or Natural Pesticides
Rotenone
 Ingredients: Derived from the roots of tropical
legumes (derris plant)
 Application: Dust onto plant – originally used
to kill fish. Kills potato beetles and cabbage
worms. Used on chickens to kill mites
 How It Works: Inhibits a cellular process,
depriving insects of oxygen in their tissue cells.
 Pros: Low residual effect. Breaks down quickly
in sunlight.
 Cons: Broad spectrum pesticide
 Precautions: Apply in the evening, when bees
are less active.
Organophosphates
Malathion and Parthion
 Extremely toxic but only remains in
the environment for a brief amount
of time.
 Effects the central nervous system
by interfering with the enzyme
cholinesterase.
Biological Pest Control
A knowledgeable gardener knows that each of
those cocoons will hatch into a beneficial
parasitic wasp - an organic control for more
than just horn worms.
Major Kinds of Herbicides
 Selective
Herbicides
– Kill only certain types of plants
– Can be classified to the type of plant
they kill
 Broad-leaf
herbicides
 Grass herbicides
– Ex: 2,4-D
 Dichlorophenoxyacetic
acid
 common systemic pesticide / herbicide used
in the control of broadleaf weeds
Risk of Pesticides to Human
Health
 Short-term
Effects of Pesticides
– Handling food with pesticide residue
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Mild case:
nausea,
vomiting,
headaches
Severe case:
damage to
nervous
system,
Risk of Pesticides to Human Health
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Long-term Effects of Pesticides
– Cancer- lymphoma
– Breast cancer
– Sterility
– Miscarriage
– Birth defects
– Decreases body’s ability to fight infection
– Potential connection to Parkinson’s
disease
Laws Controlling Pesticide Use
 Food,
Drug, and Cosmetics Act
(1938)
 Pesticide Chemicals Amendment
(1954)
 Delaney Clause (1958) (a zero cancer risk
standard)
 Federal
Insecticide, Fungicide, and
Rodenticide Act (1947) federal control of
pesticide distribution, sale, and use
 Food
Quality Protection Act (1996)
Adapted from power point by
Ms. Marosy