Environmental Effects of Pesticides

EnvironmentalEffects of Pesticides

EnvironmentalEffects of Pesticides

Photograph by Ken Hammond.

Stephen J. Toth, Jr. Wayne G. BuhlerDepartment of Entomology Department of Horticultural ScienceNorth Carolina State University North Carolina State University

Erwin W. Cole

What is theWhat is theEnvironment?Environment?

• The “environment” is everything around us natural and manmade; not limited to the outdoors, but including indoor areas in which we live and work.

Ken Hammond

How do Pesticides EffectHow do Pesticides Effectthe Environment?the Environment?

• Point-Source Pollution: contamination that comes from a specific, identifiable place (a point)

• Includes pesticide spills, wash water from cleanup sites, leaks from storage sites, and improper disposal of pesticides and their containers

Tim McCabe

How do Pesticides EffectHow do Pesticides Effectthe Environment?the Environment?

• Nonpoint-Source Pollution: contamination that comes from a wide area

• Includes the drift of pesticides through the air, pesticide run- off into waterways, pesticide movement into ground water, etc.

Bob Nichols

Environmentally-Sensitive AreasEnvironmentally-Sensitive Areas

• areas where ground water is near surface or easily accessed through wells, sinkholes, etc.

• areas near surface waters (oceans, lakes, streams)

Sensitive areas include sites or living things that are easily injured by pesticides, including:

NCSU Communication Services


• areas heavily populated with people (schools, playgrounds, hospitals, nursing homes, etc.)

• areas populated with livestock and pets


Ken Hammond


• areas near the habitats of endangered species and other wildlife

• areas near honey bees

• areas near food crops and ornamental plants


Steve Bambara

Environmental Impact of Pesticides in AirEnvironmental Impact of Pesticides in Air• The atmosphere is an important part of the hydrologic cycle• Pesticides enter the

atmosphere through drift, wind erosion and evaporation

• Pesticides can move great distances in the atmosphere

• Pesticides reach the earth’s surface via dry deposition and precipitation

U. S Geological Survey

Environmental Impact of Pesticides in AirEnvironmental Impact of Pesticides in Air

• DDT and other organochlorine pesticides detected in Arctic and Antarctic fish and mammals; used in 1960s and 1970s

• Toxaphene is still transported into Great Lakes region by winds from the Gulf of Mexico; used on cotton in the South, banned in 1982

USDA/ARS

Long-range movement of long-lived pesticides documented:


• Organochlorine insecticides (DDT, dieldrin and lindane): widespread use in 1960s and 1970s; resistant to environmental degradation

• Organophosphate insecticides (chlorpyrifos, diazinon, malathion and methyl parathion): not long-lived in environment; used heavily in the past and at present

• Triazine herbicides (atrazine): heavily-used herbicides, persistant in environment

• Acetanilide herbicides (alachlor and metolachlor): used heavily, but not as persistant as triazine herbicides

Pesticides frequently detected in the atmosphere:


Number of pesticides detected in air, rain, snow and fog. U. S. Geologic Survey (1995).


• Source of exposure to pesticides through inhalation (lungs have surface area equal to tennis court)

• Source of contamination of surface waters and ground water through dry deposition and precipitation

• Transport of pesticides from application sites to sensitive areas

• Accumulation of pesticides in the environment (soil, wildlife, etc.)

Gene Alexander

Hazards of atmospheric pesticides to humans and environment:

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in Soil

• Pesticides can move in the environment via the soil by two methods: erosion and leaching

• Erosion: soil particles which are transported by wind and water; pesticides attached to soil particles

• Leaching: downward movement of pesticides in the soil through cracks and pores

USDA Photograph

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in SoilLeachingLeaching

• Soil normally filters water as it moves downward, removing contaminants such as pesticides

• Soil and pesticide properties, geography and weather can influence the movement of pesticides (leaching)

• Pesticides that leach through soils may reach ground water

USDA Photograph

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in SoilSoil Properties That Affect LeachingSoil Properties That Affect Leaching

• Organic matter: plant and animal material decomposing in the soil; organic matter binds pesticides; the more organic matter in the soil, the less likely pesticides will leach

• Soil texture: determined by the percentage of sand, silt and clay; the higher percentage of sand, the more likely pesticides will leach

USDA Photograph

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in SoilSoil Properties That Affect LeachingSoil Properties That Affect Leaching

• Soil acidity (pH): the acidity of the soil affects chemical properties of pesticides; as the soil pH decreases (becomes more acidic), pesticides bind more to the clay in the soil making the pesticides less likely to reach the ground water Scott Bauer

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in SoilPesticide Properties That Affect LeachingPesticide Properties That Affect Leaching

• Solubility: ability to dissolve in water; the more soluble the pesticide, the more likely it will leach

• Adsorption: the ability of the pesticide to bind tightly and quickly to organic matter in the soil affects leaching; the greater the ability to bind to organic matter, the less likely pesticides will leach

• Persistence: how long the pesticide remains in the soil; pesticides degraded primarily by sunlight, soil microbes and chemicals in the soil; the more persistent a pesticide, the more likely it will leach into ground water

Environmental Impact of Pesticides in Soil Environmental Impact of Pesticides in Soil Effects of Pesticide Application on LeachingEffects of Pesticide Application on Leaching

• Rate of application: the higher the rate (amount) of pesticide applied, the greater the chance the pesticides will leach

• Application method: pesticides applied to growing plants can be absorbed by the plants or broken down by sunlight before reaching soil; soil incorporated pesticides are not exposed to sunlight and have greatest chance of leaching into ground water

Environmental Impact of Pesticides in SoilEnvironmental Impact of Pesticides in SoilEffects of Geography & Weather on LeachingEffects of Geography & Weather on Leaching

• Geography: depth from soil surface to ground water (closer ground water is to soil surface, the more pesticide leaches into ground water)

• Weather: pesticides break down faster in warm, moist soil; therefore, less likely to leach

Gene Alexander

Environmental Impact of Pesticides in Ground WaterEnvironmental Impact of Pesticides in Ground Water

• Ground water is water located beneath the earth’s surface, usually in rock or soil

• Ground water is the primary source of drinking water for 50% of population, 95% of rural residents in the United States

Ron Nichols


• At least 143 pesticides and 21 of their transformation products have been found in ground water, from every major chemical class

• Pesticides commonly found at low levels in agricultural areas (seldom exceed water- quality standards)

• Pesticides also found in non-agricultural setting such as golf courses and residential areas Ken Hammond


• Triazine (atrazine) and acetanilide (alachlor and metolachlor) herbicides: used extensively on corn and soybeans in Midwest

• Carbamate insecticide aldicarb (Temik): ground water contamination problems, sampled for extensively

Pesticides most frequently detected in ground water:

Bill Tarpenning


• High pesticide usage in the area

• High recharge of ground water by precipitation or irrigation

• High soil permeability• Well contamination is

greatest in shallow, inadequately sealed wells Tim McCabe

Factors strongly associated with pesticide contamination ofof ground water are:

Environmental Impact of Pesticides in Surface WatersEnvironmental Impact of Pesticides in Surface Waters

• Surface waters include streams, rivers, lakes, reservoirs and oceans

• Streams and reservoirs supply approximately 50% of the drinking water in United States

Ken Hammond


• Pesticides enter surface waters through run-off, wastewater discharges, atmospheric deposition (dry and precipitation), spills and ground water

• Pesticide concentrations in surface waters follow the seasonal patterns of pesticide application and run-off

U. S Geological Survey


• Low levels of pesticides are widespread in surface waters in the United States

• Herbicides are detected more frequently than insecticides, due to their greater use

• Some pesticides exceed water-quality standards during certain seasons, but the annual average concentrations seldom exceed standards Doug Wilson


• Triazine (atrazine) and acetanilide (alachlor and metolachlor) and 2,4-D herbicides: widely used in agriculture

• Carbofuran and diazinon were the most frequently detected insecticides in current use

Pesticides most frequently detected in surface waters:

Bill Tarpenning

Environmental Impact Environmental Impact of Pesticides on Plantsof Pesticides on Plants

• Pesticides can move from the intended target and damage nearby plants, including crops, forests and ornamental plants

• Phytotoxicity: plant injury resulting from contact with pesticides and/or inert ingredients in pesticide formulations

Scott Bauer

Bruce Fritz

Environmental Impact of Pesticides on WildlifeEnvironmental Impact of Pesticides on Wildlife

• Fish kills caused by pesticide residues carried into waterways by run-off, drift, etc. (e.g., fish kills in Mississippi River resulting from Guthion use in Louisiana)

• Bird kills caused by birds consuming pesticide-treated vegetation/insects, pesticide granules, bait or treated seed (e.g., birds poisoned by eating granular carbofuran)

Ken Hammond

Acute Poisoning: short exposures to some pesticides may kill or sicken wildlife


• Populations of bald eagles and other birds of prey were reduced by the widespread use of organochlorine insecticides (DDT) in 1950s and 1960s

• These compounds and metabolites caused reproductive effects in birds

• Reduction in use of organochlorine insecticides in the 1970s and early 1980s resulted in greatly improved reproduction and increasing bird populations Tim McCabe

Chronic Poisoning: exposure to non-lethal levels of pesticides over extended periods can cause reproductive effects, etc.


• Predators become sick after feeding on dead or dying animals poisoned by pesticides

• Pesticide residues move up the food chain (plants eaten by plant feeding animals which in turn are eaten by predators)

USDA Photograph

Secondary Poisoning: occurs when animals consume prey that contain pesticide residues and concentrate the pesticide in their bodies (i.e., bioaccumulation) resulting in their poisoning


• Herbicides can reduce food, cover and nesting sites for wildlife

• Insecticides can reduce insects that serve as food supply for other animals

• Plant pollination can be effected by reductions in populations of bees and other plant pollinators

Ken Hammond

Indirect Effects: adverse effects caused by the modification or elimination of wildlife habitat or food supply

Endangered and Threatened SpeciesEndangered and Threatened Speciesof Plants and Animalsof Plants and Animals

• Endangered species: “any species which is in danger of extinction throughout all or a significant portion of its range”

• Threatened species: “any species which is likely to become an endangered species within the foreseeable future”

• Endangered / threatened species of plants and animals protected by the U. S. EPA under the federal Endangered Species Act

Tim McCabe

Harmful Effects of Pesticides on SurfacesHarmful Effects of Pesticides on Surfaces

• Pesticides can leave a visible deposit on surfaces (i.e., clothes, carpets, walls, etc.)

• Pesticides can corrode metal surfaces (i.e., paint on automobiles)

• Pesticides can short-circuit electrical equipment

N. C. Pesticide Applicator Training Program

ReferencesReferences

• Applying Pesticides Correctly: A Guide for Private and Commercial Applicators. Unit 4: Pesticides in the Environment. pp. 39-48.

• Applying Pesticides Correctly: A Guide for Private and Commercial Applicators. Unit 5: Special Environmental Concerns. pp. 49-59.

• McLaughlin, R. A., J. B. Weber, and R. L. Warren. 1994. Protecting Groundwater in North Carolina: A Pesticide and Soil Ranking System. AG-439-31. N. C. Cooperative Extension Service, Raleigh. 6 pp. (http://ces.soil.ncsu.edu/soilscience/publications/Soilfacts/AG-439-31/)

• U. S. Geologic Survey. 1995. Pesticides in the Atmosphere: Current Understanding of Distribution and Major Influences. Fact Sheet FS-152-95. U. S. Geologic Survey, U. S. Dept. of the Interior. 4 pp. (http://water.wr.usgs.gov/pnsp/atmos/)

ReferencesReferences• U. S. Geologic Survey. 1995. Pesticides in Ground Water: Current

Understanding of Distribution and Major Influences. Fact Sheet FS-244-95. U. S. Geologic Survey, U. S. Dept. of the Interior. 4 pp. (http://water.wr.usgs.gov/pnsp/gw/)

• U. S. Geologic Survey. 1997. Pesticides in Surface Waters: Current Understanding of Distribution and Major Influences. Fact Sheet FS-039-97. U. S. Geologic Survey, U. S. Dept. of the Interior. 4 pp. (http://water.wr.usgs.gov/pnsp/gw/)

• Whitford, F., Miller, B., Bennett, R., Jones, M., and Blesoe, L. 1994. Pesticides and Wildlife: An Introduction to Testing, Registration, and Risk Management. Publication PP-30. Purdue University Cooperative Extension Service, West Lafayette, Indiana. pp. 6-7. (http://www.agcom.purdue.edu/AgCom/Pubs/PPP/PPP-30.html)

Environmental Effects of Pesticides

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