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”

• 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)

500 BCSulfur

1400’s

As, Pb, Hg

Heavy Metals, highly toxic)

1600’s

Nicotine (SiO4) from tobacco leaves

1800’s Botanicals

Pyrethrum (rotenone)

From flower heads of chrysanthemum flower and tropical legumes (pyrethroids)

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-diphenyl-trichloroethane )

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 life-threatening if not treated.

Endemic in more than 100 countries.Caused by four protozoa species.270–500 million new cases and1 million deaths per year.Malaria

Figure 19-14Page 425

Anopheles mosquito (vector)in aquatic breeding area

1. Femalemosquito bitesinfected human,ingesting bloodthat containsPlasmodiumgametocytes

4. Parasite invadesblood cells, causingmalaria and makinginfected persona new reservoir

3. Mosquito injects Plasmodiumsporozoites into human host

2. Plasmodiumdevelops inmosquito

eggs

larvapupa

adult

Life-Cycle of Malaria

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 (half-life = 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-eatingbirds (ospreys)

25 ppm

DDT in largefish (needle fish)2 ppm

DDT in smallfish (minnows)0.5 ppm

DDT inzooplankton0.04 ppm

DDT in water0.000003 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.

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• 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 DESTRUCTIONChlorine 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

THINNINGAs 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. Cultivation Practices2. Biological Control – release natural predators3. Biopesticides4. Insect Birth Control (Asian Long-horned Beetle)5. Pheremones (insect sex attractants)6. Hot water zapping7. Gamma radiation (zapping foods)8. IPM’s

Integrated Pest Management (IPM’s)

• 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?a. Add sales tax to pesticides (subsidy to gain $ to promote sustainable

agricultural methods)b. Set up demonstration sites and educational seminars, not only for farmers

but for homeowners.c. Provide training for homeowners.d. Create federal and state subsidies to promote sustainability and deter

environmentally degrading practices. Reward those who practice sustainable methods!

e. 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.

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