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BIOCIDES
What is a Pest?
• A pest is any species that
competes with US for food
(rabbits), invade gardens
(aphids, caterpillars) and
lawns (grubs, snails, slugs),
destroys wood in houses
(carpenter ants, termites),
spreads disease (fleas,
cockroaches, mosquitoes,
ticks), or is a nuisance
(raccoons, squirrels, Canada
Geese).
Biocides “Pesticides”
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Insecticide – kills insects
Herbicide – kills weeds
Fungicides – kill fungi
Nematocides – kill roundworm
Rodenticide – kill rodents
Algicide – kills algae
Larvicide – kills larvae
Facts
• Over 3 million metric tons of biocides are
used annually on Earth (1 lb. per person)
• Approximately 25% of the biocides used in
the USA are used to rid houses, gardens,
lawns, parks, playing fields, swimming
pools, and golf courses of unwanted pests.
• The average USA homeowner applies 2-6
times more biocides per acre than farmers
do!
Biocide Definitions
• Broad-spectrum agents: toxic to many
species
• Narrow-spectrum agents: effective against
a narrowly defined group of organisms.
• Persistence – the length of time the
biocide remains deadly in the
environment.
Biocide History
• Until the 1950’s, farmers had two weapons
to use against crop pests; natural
pesticides found in plants and minerals
containing arsenic, lead, and mercury
(heavy metals!)
Biocide History (1st & 2nd
Generation Pesticides)
1400’s
As, Pb, Hg
Heavy
Metals,
highly toxic)
500 BC
Sulfur
1800’s Botanicals
Pyrethrum (rotenone)
From flower heads of
chrysanthemum flower and tropical
legumes (pyrethroids)
1600’s
Nicotine
(SiO4) from
tobacco
leaves
1900’s Second
Generation Pesticides
= synthhetic organic
chemicals (SOC’s)
Biocide History
• Homeowners used natural defenses that few people use
today because of the easy access and affordability of
pesticides.
• Ants – cayenne pepper, crushed mint leaves, or boric
acid, vinegar.
• Mosquitoes – basil plants or rubbing basil oil, lime juice,
or mugwort (weed) oil on bare skin.
• Cockroaches – boric acid, or establishing banana spider
populations (not recommended, one of the deadliest
spiders from Australia)
• Fleas – feed pets brewer’s yeast or use flea repellent
soaps.
• Garden pests – introduce natural predators.
• Ex. Ladybugs LOVE aphids!
Also introduce insect-eating birds, toads
and frogs, fish, and snakes.
Biocide History – Development of
Synthetic Organic Compounds
• The use of SOC’s has revolutionized
modern agriculture by allowing food
production to more than double in
developed countries and increase by
120% in developing countries!
• SOC’s include pesticides, herbicides, and
chemical fertilizers.
Argument for Biocides
1. Pesticides increase food supplies and lower food costs
for consumers.
2. Pesticides increase profits for farmers.
3. Pesticides work faster and better than natural
alternatives as effective killers of pests.
4. The pesticide industry declares that the health risk of
pesticides is insignificant compared with their benefits
for food resources and boost to general health.
5. Many “new” pesticides are used at very low rates per
unit area compared to “old” pesticides
Argument Against Pesticides
1. Pests develop genetic resistance. They will
survive and breed and make a second
generation more resistant. Must increase
concentration or combination of chemicals to
be effective. “evolutionary arms race”
Becomes a “Pesticide Treadmill”; a situation
where farmers pay more and more for pest
control that are less and less effective due to
insects development of genetic resistance.
Argument Against Pesticides
2.
Broad-spectrum pesticides kill natural predators and
parasites that may have been maintaining a pest
species population at a reasonable level.
The “ideal” pesticide would:
•
Kill only the target pest and harm no other species.
•
Disappear quickly and breakdown into something
harmless in the environment.
•
Not cause genetic resistance to target organisms.
•
Be cheap when true costing occurs (internalities +
externalities)
Argument Against Pesticides
(SOC’s)
• Pesticides bioaccumulate and biomagnify
in the environment and in food webs.
• A compound is toxic to a wide range of
organisms and is persistent in the
environment.
• Example DDT (dichloro-diphenyltrichloroethane )
Major Classes of Pesticides
1. Insecticides – DDT; high persistence,
biologically magnified, broad-spectrum
2. Herbicides –low persistence (days to weeks),
not biologically magnified, narrow spectrum.
3. Fungicides –lowest persistence (several days),
not biologically magnified, narrow spectrum
4. Fumigants –high persistence, biologically
magnified, broad spectrum.
DDT Case Study
• DDT is a chlorinated hydrocarbon and is used
as an insecticide.
• DDT was first synthesized in 1874 but was
forgotten until 1939 when Swiss chemist Paul
Mueller found that DDT was highly toxic to
insects.
• The Swiss government immediately began to
use DDT against a major pest, the Colorado
potato beetle.
DDT continued
• For two decades DDT was used in
agriculture against insect pests and by
medical workers against disease-carrying
organisms.
• Malaria is a mosquito-transmitted
disease (Anopholese mosquito is the
vector species) causing fever, headache,
vomitting, etc… and can become lifethreatening if not treated.
Malaria
Endemic in more than 100 countries.
Caused by four protozoa species.
270–500 million new cases and
1 million deaths per year.
Figure 19-14
Page 425
Anopheles mosquito (vector)
in aquatic breeding area
eggs
adult
larva
pupa
Life-Cycle
of Malaria
1. Female
mosquito bites
infected human,
ingesting blood
that contains
Plasmodium
gametocytes
4. Parasite invades
blood cells, causing
malaria and making
infected person
a new reservoir
2. Plasmodium
develops in
mosquito
3. Mosquito injects Plasmodium
sporozoites into human host
Problems with DDT
• DDT is toxic ( toxicity = the measure of how
harmful a substance can be to organisms)
• DDT is persistent in the environment. The half life of DDT ranges from 3-10 years in soil (halflife = the time it takes for the concentration of
that substance to be reduced by half in a
biological system)
• DDT breaks down to DDE which is persistent in
the environment for 200 years and is more toxic
than DDT!
Problems with DDT
• DDT is soluble in fats; when organisms
digest DDT, the pesticide concentrates in
fatty parts of the body.
• This allows DDT to be passed along in the
food web (bioaccumulate)
• DDT is biomagnified.
DDT in fish-eating
birds (ospreys)
25 ppm
DDT in large
fish (needle fish)
2 ppm
DDT in small
fish (minnows)
0.5 ppm
DDT in
zooplankton
0.04 ppm
DDT in water
0.000003 ppm,
Or 3 ppt
“CIRCLE OF POISON”
Problems with DDT
• Some animals no longer reproduce normally when
exposed to DDT
• Predatory birds at the top of the food chain lay eggs with
unusually thin shells
• DDE blocks the formation of calcium in egg production in
the female.
• This caused the near extinction of the American bald
eagle, osprey, and peregrine falcon.
Rachel Carson and DDT
• Rachel Carson – biologist for
Bureau of US Fisheries (later
USFWS), became Editor in
Chief for bureau’s publications
in 1949.
• 1951 – wrote “The Sea Around
Us” about the natural history of
the oceans and anthropogenic
effects.
• Book was on the best seller list
for 86 weeks, sold 2 million
copies, was translated in 32
languages, and won a National
Book Award.
Rachel Carson
• In 1958 DDT was sprayed to control mosquitoes
near the home and private bird sanctuary of one
of Rachel’s friends (Olga Huckins).
• After the sprayings, many of the birds died
horrible deaths, so she asked Carson to
investigate the effects of pesticides on birds and
other wildlife.
• Initially, she found there was no independent
critical research on environmental effects of
pesticides.
Rachel Carson
• Carson surveyed the scientific
literature and methodically built her
case against the widespread use of
pesticides.
• 1962 she published “Silent Spring”;
an allusion to the silencing of robins,
catbirds, doves, jays, and wrens and
scores of other bird voices because of
their exposure to pesticides.
• She pointed out that “for the first time
in the history of the world, every
human being is now subjected to
dangerous chemicals, from the
moment of conception until death.”
Opposition to Silent Spring
• Although the public embraced her book, the chemical industry viewed
the book as a serious threat to booming pesticide sales.
• The chemical industry mounted a $250,000 campaign to discredit
Carson.
• Chemical Industry scientists claimed that her book was full of
inaccuracies, made selective use of research findings, and failed to
give a balanced account of the benefits of pesticides.
• Critics claimed that “as a woman, she was incapable of
understanding the highly scientific and technical subject of
pesticides”..
• Others claimed she was a hysterical woman and a radical nature
lover trying to scare the American public in order to sell books.
• 18 months after Silent Spring was published, Rachel Carson died
from terminal cancer.
Silent Spring became one of the driving forces for the Environmental
Movement in the United States!
DDT Banned in USA
• 1973 The Environmental Protection Agency
(EPA) banned the use of DDT in the USA.
• 1986 – a study on humans showed that an
average level of 1.67 ppm of DDT was retained
in fatty tissue, more than 10 years after the
compound had been banned. The acceptable
limit for DDT in human tissue is 0.2 ppm!
DDT in Breast Milk Around the
World
• DDT is found to be
significantly high in
developing nations who still
continue spraying DDT for
malaria control.
• The USA is still the largest
manufacturer of DDT in the
world!
• DDT travels through the
wind belts around the world.
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Chaos
in
Borneo
World Health Organization (WHO) sent supplies of DDT to Borneo to
combat malaria and kill mosquitoes.
It was very successful and wiped out the mosquito population quickly.
The billions of cockroaches that lived in the village stored the DDT in
their tissue.
Small lizards fed on the roaches who became weakened by the DDT
and slowed down.
Cats were able to catch the lizards more easily (favorite food).
Since the cats ate a lot of lizards and the DDT biomagnified through
the food web, the cats began to die.
Once the cat population decreased, the rats moved in (no natural
predators).
The lizard population declined because of the cats predating on them
and a caterpillar population that used to be maintained by the lizards
was now increasing and feeding on the roof material of the homes of
the villagers.
The homes began to collapse.
Emergency workers sent emergency calls for more cats!
Cats were parachuted in to Borneo to kill the rats who were spreading
disease (plague)!
Insecticides
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Insecticides are chlorinated
hydrocarbons and include:
DDT
Aldrin and dieldrin;
organochlorine pesticides to treat
termites, grasshoppers,
woodborers, beetles – impacts to
central nervous system. Dieldrin
was used to control tse-tse fly to
prevent tropical diseases.
Causes tremors, disorientation
and liver problems.
Chlordane – banned in 1990.
Used to treat lawn, turf and
ornamentals. Affects lungs,
nervous system, and liver.
Organophosphates – (parathion
and malathion) Spray for West
Nile Virus on Long Island
Aldrin
Dieldrin
West Nile Virus
West Nile Virus
• West Nile Virus (WNV) is a mosquito-borne virus that can cause
encephalitis or meningitis-- an inflammation of the brain -- in humans
and other animals. People get West Nile from the bite of a mosquito
that is infected with West Nile virus. Mosquitoes become infected
with West Nile virus when they feed on infected birds that carry the
virus in their blood. West Nile virus is NOT transmitted from person
to person.
• West Nile virus is closely related to two other mosquito-borne
encephalitis viruses in the United States : St. Louis Encephalitis
(SLE) and Eastern Equine Encephalitis (EEE). These viruses have
been responsible for illnesses requiring hospitalization of over a
hundred people in Michigan , with several deaths. Some of these
viruses have also caused equine illness with over 200 horse deaths
confirmed.
AVIAN MIGRATORY FLYWAYS
How Did West Nile Virus Get Here?
Hypothesis 1: Avian migratory pathways. First outbreaks
in USA were in Queens Long Island, 1999. North Atlantic
Flyway is the first western flyway for neotropical birds
flown off course during storms from Black Sea
Mediterranean Flyway (Nile River Region).
Hypothesis 2: First terror attack on USA was biological.
Evidence that in 1996 Sadaam Hussein made a very
large purchase of West Nile Virus from US Biological
Supply Companies (traced through chain of custody) and
that Queens, New York was the release point. Easy to
do by releasing into ponds where mosquitoes breed and
larvae develop, become infected and females spread the
disease.
Carbamates
• Carbamates replaced
many of the halogenated
hydrocarbons (Aldicarb)
and is used primarily as a
molluscicide
Aldicarb
Fumigants
• Carbon tetrachloride, ethelyne dibromide,
and methylbromide.
• The chemicals used for fumigants are also
used in dry cleaning agents and freon
refrigerants.
Botanicals
• Rotenone and pyrethrum – also used on Long
Island to spray for West Nile Virus.
• Persistence – low (days to weeks), EPA claims
they are not biologically magnified in the
environment.
• Sprayed at “unnatural” concentrations
• CHILDREN AND THE ELDERLY OR PEOLPLE
WHO ARE IMMUNOCOMPROMISED ARE AT
THE GREATEST RISK TO PESTICIDE
POISONING AND TUMOR GROWTH.
Parkinson’s Disease
• Researchers have found a link to Parkinson’s Disease (a
neurodegenerative disorder) and the botanical pesticide rotenone.
• When Michael J. Fox was diagnosed with Parkinson’s Disease, he
promoted the need for research and a tremendous amount of money
has been targeted toward identifying causes and promoting
research to find cures for this disease.
• Parkinsons’ Disease was first described by James Parkinson in
1817. The condition kills the nerve cells in the brain that release
dopamine, a chemical necessary for controlling body movements.
• To reduce the risk of Parkinson’s Disease, Consumers must reduce
their exposure to pesticides by washing residue off of foods, not
using sanitizers and mildew removers which contain pesticides, and
not applying them on their lawns or in their gardens.
How Dangerous Are Biocides?
• 50,000 different pesticides are used in the USA!
• Hazardous risk to humans depends on:
a. Concentration of pesticide in environment or
inhaled or ingested.
b. How much is absorbed and retained in
drinking water or crop. (The higher the solubility,
the more dangerous the compound will be.)
c. The duration of exposure to the chemical.
d. How quickly the compound is metabolized
and excreted from the body.
How Dangerous Are Biocides?
• EPA defines “acceptable risk” of biocides in our drinking
water to be “one that causes no more than one
additional case of cancer in a population of a million
people who drink the water over the course of a lifetime”
• How can we determine if a person’s cancer has been
directly caused by ingestion of contaminated drinking
water when all of the foods we eat are loaded with
carcinogens and when the air we breathe are loaded
with hydrocarbons and other toxins from burning fossil
fuels, smelting ores, and industrial production of goods?
How Dangerous Are Fumigants?
• Fumigants are released
through gas cartridges
(gases) that infiltrate
every crack and space
in a room or below
ground.
• When released, the
area must be well
ventilated and humans
and domestic animals
may not re-enter for 6 –
8 hours after treatment.
• What do you think?
Fumigants in the Atmosphere
• Carbon tetrachloride and chlorides used in
refrigeration processes (freon) are the
direct cause to the thinning of the ozone
layer.
AIR POLLUTANTS FROM
COOLANTS
Ozone (O3) in the stratosphere forms when HQE UV photons break
apart diatomic O2(g) molecules forming reactive free radicals O. The
free radicals combine with other diatomic molecules of O2 to from
O3.
Importance: Each ozone molecule in the stratosphere can absorb a
UV photon with a wavelength less than 320 nm. This energy
absorption prevents potentially harmful UV rays from reaching the
earth’s surface.
OZONE DESTRUCTION
Chlorine from chlorofluorocarbons (CFC’s) emitted from refrigerators,
and air conditioners and include freons are highly stable molecules in the
troposphere.
Chlorine atoms emitted from fumigants migrate upward in the
atmosphere.
HQE UV photons in the stratosphere split chlorine radicals from CFC’s
by breaking the C-Cl bond.
The Cl radicals are very reactive and can participate in a series of
photochemical reactions that destroy O3 by converting it to O2. When free
radicals of O combine to form diatomic molecules of oxygen they prevent
additional atoms of O3 from forming.
Every Cl radical can destroy on average 100,000 O3 molecules!
OZONE THINNING
IMPACTS TO HUMAN
HEALTH FROM OZONE
THINNING
As O3 layer in stratosphere continues to thin, more UV-B
radiation will pass through the stratosphere into the troposphere
and cause squamous cell cancer and cataracts in humans.
Other human health issues include suppression of the immune
system,, lower yields of key crops, serious decline in
phytoplankton and forest productivity, and deeper penetration of
UV radiation into lakes disrupting ecosystem structure and
function.
OZONE HOLE?
SOLUTIONS
 It will take 50-60 years to return to 1975 levels and 100-200 years to
return to 1950 levels.
 Use substitutes such as hydrochloroflurocarbons (HCFC’s); less Cl
molecules and have shorter lifespan in stratosphere. Can still
cause O3 depletion. Other substitutes are hydrofluorocarbons
(HJFC’s), propane, and butane.
 Developing nations can us HC technology to leap ahead of
Industrialized nations. HC’s cannot be patented!
 Implement plans and policies to deter CFC useage.
MONTREAL PROTOCOL
1987 – 36 nations met in Montreal to develop a treaty to cut emissions of
CFC’s by 35% between 1989 and 2000.
1990 – 93 countries met in London
1992 - 92 nations met in Copenhagen
1997 – 92 nations met in Montreal once again and adopted a protocol
accelerating the phase out of key ozone-depleting chemicals.
BEST EXAMPLE – global cooperation in response to serious threats to
global environmental security. Developed nations set up over $250 million
fund to help developing nations not use CFC’s and phase it out early in their
transition to a developed nation.
MONTREAL PROTOCOL
Synergism
• Synergistic effects – when low or acceptable
concentrations of hazardous materials or toxins exist in
the environment (air, water or soil), the combined effect
of ALL of them often prove EXTREMELY harmful to
human health and the overall health of ecosystems.
OTHER SOLUTIONS FOR
CONTROLLING PESTS AND
PROTECTING HUMAN HEALTH
AND ECOSYSTEMS
1.
2.
3.
4.
5.
6.
7.
8.
Cultivation Practices
Biological Control – release natural predators
Biopesticides
Insect Birth Control (Asian Long-horned Beetle)
Pheremones (insect sex attractants)
Hot water zapping
Gamma radiation (zapping foods)
IPM’s
Integrated Pest Management
(IPM’s)
•
•
•
a.
b.
c.
d.
e.
Aim: Reduction of crop damage to economically tolerable levels and NOT
eradication of pests!
Ecosystem Approach using biological, chemical, and cultivation
(mechanical) methods.
How Can This Be Achieved?
Add sales tax to pesticides (subsidy to gain $ to promote sustainable
agricultural methods)
Set up demonstration sites and educational seminars, not only for farmers
but for homeowners.
Provide training for homeowners.
Create federal and state subsidies to promote sustainability and deter
environmentally degrading practices. Reward those who practice
sustainable methods!
THERE IS AN URGENCY IN THIS COUNTRY TO REFORM CAMPAIGN
CONTRIBUTION PRACTICES SO THAT CITIZENS AND NOT
INDUSTRIES BECOME THE VOICE OF OUR GOVERNMENT ONCE
AGAIN!
The Good News Is…
• Between 1972 and 1996, the EPA banned 55
active pesticide ingredients known to be
carcinogenic or biomagnify in the environment.
• 1996 Food Quality Protection Act – EPA set
new standards for pesticide tolerance levels in
foods.
• Manufacturers of pesticides must demonstrate
active ingredients are safe for infants, children,
etc…
• EPA must develop new screening for
active/inactive ingredients to protect human
health risk.
FIFRA
• FIFRA = Federal Insecticide, Fungicide,
and Rodenticide Act
• It requires ALL commercial pesticides to
be approved by the EPA (sets tolerance
levels) for general and/or restricted use.
What Can You Do?
• 1. Build healthy soil – Add 2-3 inches of compost each year to
improve the organic content of your soil.
• 2. Grow plants native to the northeast – they will be tolerant of
climactic conditions and possess genetic resistance to many pests
through natural selection.
• 3. Create diverse gardens to attract local wildlife –
butterfly/hummingbird gardens, seed-producing perennials that
provide nutrients during avian migratory seasons. Include trees and
shrubs with berries.
• 4. Manage plant problems with safe, nontoxic solutions by
introducing natural predators, using herbs and spices that naturally
deter pests, and interplanting marigolds and chrysanthemum within
your garden (strong chemical defense against pests).
• 5. Improve your lawn by adding compost, introducing earthworms
(aeration, pulling weeds). Reduce the size of your lawn by
increasing xerophytic gardens around your property.