1. Environmental Effects of Pesticides
Stephen J. Toth, Jr. Wayne G. Buhler
Department of Entomology Department of Horticultural Science
North Carolina State University North Carolina State University
Photograph by Ken Hammond.

2. What is the 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.
Erwin W. Cole
Ken Hammond

3. How do Pesticides Effect 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

4. How do Pesticides Effect 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

5. Environmentally-Sensitive Areas
Sensitive areas include sites or living things that are easily injured by pesticides, including:
areas where ground water is near surface or easily accessed through wells, sinkholes, etc.
areas near surface waters (oceans, lakes, streams)
NCSU Communication Services

6. Environmentally-Sensitive Areas
Sensitive areas include sites or living things that are easily injured by pesticides, including:
areas heavily populated with people (schools, playgrounds, hospitals, nursing homes, etc.)
areas populated with livestock and pets
Ken Hammond

7. Environmentally-Sensitive Areas
Sensitive areas include sites or living things that are easily injured by pesticides, including:
areas near the habitats of endangered species and other wildlife
areas near honey bees
areas near food crops and ornamental plants
Steve Bambara

8. Environmental 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

9. Environmental Impact of Pesticides in Air
Long-range movement of long-lived pesticides documented:
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

10. Environmental Impact of Pesticides in Air
Pesticides frequently detected in the atmosphere:
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

11. Environmental Impact of Pesticides in Air
Number of pesticides detected in air, rain, snow and fog. U. S. Geologic Survey (1995).

12. Environmental Impact of Pesticides in Air
Hazards of atmospheric pesticides to humans and environment:
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

13. Environmental 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

14. Environmental Impact of Pesticides in Soil Leaching
USDA Photograph
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

15. Environmental Impact of Pesticides in Soil Soil 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

16. Environmental Impact of Pesticides in Soil Soil 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

17. Environmental Impact of Pesticides in Soil Pesticide 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

18. Environmental Impact of Pesticides in Soil Effects 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

19. Environmental Impact of Pesticides in Soil Effects 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

20. Environmental 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

21. Environmental Impact of Pesticides in Ground Water
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

22. Environmental Impact of Pesticides in Ground Water
Pesticides most frequently detected in ground water:
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
Bill Tarpenning

23. Environmental Impact of Pesticides in Ground Water
Factors strongly associated with pesticide contamination of
of ground water are:
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

24. Environmental 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

25. Environmental Impact of Pesticides in Surface Waters
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

26. Environmental Impact of Pesticides in Surface Waters
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

27. Environmental Impact of Pesticides in Surface Waters
Pesticides most frequently detected in surface waters:
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
Bill Tarpenning

28. Environmental Impact of 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

29. Environmental Impact of Pesticides on Wildlife
Acute Poisoning: short exposures to some pesticides may kill or sicken 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

30. Environmental Impact of Pesticides on Wildlife
Chronic Poisoning: exposure to non-lethal levels of pesticides over extended periods can cause reproductive effects, etc.
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 s resulted in greatly improved reproduction and increasing bird populations
Tim McCabe

31. Environmental Impact of Pesticides on Wildlife
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
USDA Photograph
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)

32. Environmental Impact of Pesticides on Wildlife
Indirect Effects: adverse effects caused by the modification or elimination of wildlife habitat or food supply
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

33. Endangered and Threatened Species of 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

34. Harmful 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