- Environmental effects of pesticides
Use of pesticides can have unintended effects on the environment.
Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including nontarget species, air, water, bottom sediments, and food.Miller GT (2004), "Sustaining the Earth", 6th edition. Thompson Learning, Inc. Pacific Grove, California. Chapter 9, Pages 211-216.] Pesticide contaminates land and water when it escapes from production sites and storage tanks, when it runs off from fields, when it is discarded, when it is sprayed aerially, and when it is sprayed into water to kill algae.Tashkent (1998), [http://bpsp-neca.brim.ac.cn/books/actpln_uzbek/part1-3.html#Table%20E:%20Application%20rates%20of%20Pesticides%20and%20Defoliants%20(1990/1993) Part 1. Conditions and provisions for developing a national strategy for biodiversity conservation] . Biodiversity Conservation National Strategy and Action Plan of Republic of Uzbekistan. Prepared by the National Biodiversity Strategy Project Steering Committee with the Financial Assistance of The Global Environmental Facility (GEF) and Technical Assistance of United Nations Development Programme (UNDP). Retrieved on
September 17, 2007.] The amount of pesticide that migrates from the intended application area is influenced by the particular chemical's properties: its propensity for binding to soil, its vapor pressure, its water solubility, and its resistance to being broken down over time.Kellogg RL, Nehring R, Grube A, Goss DW, and Plotkin S (February 2000), [http://www.nrcs.usda.gov/Technical/land/pubs/eip_pap.html Environmental indicators of pesticide leaching and runoff from farm fields] . United States Department of Agriculture Natural Resources Conservation Service. Retrieved on 2007-10-03.] Factors in the soil, such as its texture, its ability to retain water, and the amount of organic matter contained in it, also affect the amount of pesticide that will leave the area.
Some pesticides contribute to
global warmingand the depletion of the ozone layer.Reynolds, JD (1997), [http://www.law.fsu.edu/journals/landuse/Vol131/REYN.HTMl International pesticide trade: Is there any hope for the effective regulation of controlled substances?] "Florida State University Journal of Land Use & Environmental Law", Volume 131. Retrieved on 2007-10-16.]
Pesticides can contribute to air pollution . Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them.Cornell University. [http://pmep.cce.cornell.edu/facts-slides-self/core-tutorial/module06/index.html Pesticides in the environment] . Pesticide fact sheets and tutorial, module 6. Pesticide Safety Education Program. Retrieved on
2007-10-11.] Pesticides that are applied to crops can volatilize and may be blown by winds into nearby areas, potentially posing a threat to wildlife. [National Park Service. US Department of the Interior. (August 1, 2006), [http://www.nps.gov/seki/naturescience/air_synthchem.htm Sequoia & Kings Canyon National Park: Air quality -- Airborne synthetic chemicals] . Nps.gov. Retrieved on September 19, 2007.] Also, droplets of sprayed pesticides or particles from pesticides applied as dusts may travel on the wind to other areas, [US Environmental Protection Agency (September 11th, 2007), [http://www.epa.gov/PR_Notices/prdraft-spraydrift801.htm Pesticide registration (PR) notice 2001-X Draft: Spray and dust drift label statements for pesticide products] . Epa.gov. Retrieved on September 19, 2007.] or pesticides may adhere to particles that blow in the wind, such as dust particles. [Environment Canada (September-October 2001), [http://www.ec.gc.ca/science/sandesept01/article3_e.html Agricultural pesticides and the atmosphere] . Retrieved on 2007-10-12.] Ground spraying produces less pesticide drift than aerial spraying does. Farmers can employ a buffer zone around their crop, consisting of empty land or non-crop plants such as evergreen trees to serve as windbreaks and absorb the pesticides, preventing drift into other areas."Science Daily" (November 19, 1999), [http://www.sciencedaily.com/releases/1999/11/991119075237.htm Evergreens help block spread of pesticide from crop fields] . Sciencedaily.com. Retrieved on September 19, 2007.] Such windbreaks are legally required in the Netherlands.
Pesticides that are sprayed onto fields and used to fumigate soil can give off chemicals called
volatile organic compounds, which can react with other chemicals and form a pollutant called ozone, accounting for an estimated 6% of the total ozone production. [UC IPM Online. (August 11, 2006), [http://www.ipm.ucdavis.edu/NEWS/carrot-news.html What’s up, Doc? Maybe less air pollution] . Statewide IPM Program, Agriculture and Natural Resources, University of California. Ipm.ucdavis.edu. Retrieved on 2007-10-15.]
United States, pesticides were found to pollute every stream and over 90% of wells sampled in a study by the US Geological Survey. [Gilliom, RJ, Barbash, JE, Crawford, GG, Hamilton, PA, Martin, JD, Nakagaki, N, Nowell, LH, Scott, JC, Stackelberg, PE, Thelin, GP, and Wolock, DM (February 15, 2007), [http://pubs.usgs.gov/circ/2005/1291/ The Quality of our nation’s waters: Pesticides in the nation’s streams and ground water, 1992–2001] . Chapter 1, Page 4. US Geological Survey. Retrieved on September 13, 2007.] Pesticide residues have also been found in rain and groundwater. Studies by the UK government showed that pesticide concentrations exceeded those allowable for drinking water in some samples of river water and groundwater. [Bingham, S (2007), [http://www.environment-agency.gov.uk/yourenv/eff/1190084/business_industry/agri/pests/915588/?version=1&lang=_e Pesticides in rivers and groundwater] . Environment Agency, UK. Retrieved on 2007-10-12.]
Pesticide impacts on aquatic systems are often studied using a
hydrology transport modelto study movement and fate of chemicals in rivers and streams. As early as the 1970s quantitative analysis of pesticide runoff was conducted in order to predict amounts of pesticide that would reach surface waters. [Hogan,, CM, Patmore L, Latshaw, G, Seidman, H, et al. (1973), " Computer modeling of pesticide transport in soil for five instrumented watersheds", U.S. Environmental Protection Agency Southeast Water laboratory, Athens, Ga. by ESL Inc., Sunnyvale, California.]
There are four major routes through which pesticides reach the water: it may drift outside of the intended area when it is sprayed, it may percolate, or leach, through the soil, it may be carried to the water as runoff, or it may be spilled, for example accidentally or through neglect. [States of Jersey (2007), [http://www.gov.je/PlanningEnvironment/Environment/Environmental+Protection/Environmental+Protection+and+Pesticide+use.htm Environmental protection and pesticide use] . Retrieved on
2007-10-10.] They may also be carried to water by eroding soil. [Papendick RI, Elliott LF, and Dahlgren RB (1986), [http://eap.mcgill.ca/MagRack/AJAA/AJAA_1.htm Environmental consequences of modern production agriculture: How can alternative agriculture address these issues and concerns?] "American Journal of Alternative Agriculture", Volume 1, Issue 1, Pages 3-10. Retrieved on 2007-10-10.] Factors that affect a pesticide's ability to contaminate water include its water solubility, the distance from an application site to a body of water, weather, soil type, presence of a growing crop, and the method used to apply the chemical.Pedersen, TL (June 1997), [http://extoxnet.orst.edu/faqs/safedrink/pest.htm Pesticide residues in drinking water] . extoxnet.orst.edu. Retrieved on September 15, 2007.]
Maximum limits of allowable concentrations for individual pesticides in public bodies of water are set by the
Environmental Protection Agencyin the US. Similarly, the government of the United Kingdom sets Environmental Quality Standards (EQS), or maximum allowable concentrations of some pesticides in bodies of water above which toxicity may occur.Bingham, S (2007), [http://www.environment-agency.gov.uk/yourenv/eff/1190084/business_industry/agri/pests/917555/?version=1&lang=_e Pesticides exceeding environmental quality standards (EQS)] . The Environment Agency, UK. Retrieved on 2007-10-12.] The European Union also regulates maximum concentrations of pesticides in water.
Many of the chemicals used in pesticides are persistent
soil contaminants, whose impact may endure for decades and adversely affect soil conservation. [ USEPA(2007), [http://www.epa.gov/superfund/programs/er/hazsubs/sources.htm Sources of common contaminants and their health effects] . Epa.gov. Retrieved on 2007-10-10.]
The use of pesticides decreases the general
biodiversityin the soil. Not using the chemicals results in higher soil quality, [cite journal | author=Johnston, AE | title=Soil organic-matter, effects on soils and crops | journal=Soil Use Management | year=1986 | volume=2 | pages=97–105 | doi=10.1111/j.1475-2743.1986.tb00690.x] with the additional effect that more organic matter in the soil allows for higher water retention. This helps increase yields for farms in droughtyears, when organic farms have had yields 20-40% higher than their conventional counterparts. [cite journal | author=Lotter DW, Seidel R, and Liebhardt W | title=The performance of organic and conventional cropping systems in an extreme climate year | journal=American Journal of Alternative Agriculture | year=2003 | volume=18 | pages=146–154 | doi=10.1079/AJAA200345] A smaller content of organic matter in the soil increases the amount of pesticide that will leave the area of application, because organic matter binds to and helps break down pesticides.
Nitrogen fixation, which is required for the growth of higher plants, is hindered by pesticides in soil.Rockets, Rusty (June 8, 2007), [http://www.scienceagogo.com/news/farming.shtml Down On The Farm? Yields, Nutrients And Soil Quality] . Scienceagogo.com. Retrieved on September 15, 2007.] The insecticides DDT, methyl parathion, and especially pentachlorophenolhave been shown to interfere with legume- rhizobiumchemical signaling. Reduction of this symbiotic chemical signaling results in reduced nitrogen fixation and thus reduced crop yields. Root noduleformation in these plants saves the world economy $10 billion in synthetic nitrogen fertilizerevery year. [cite journal | author=Fox, JE, Gulledge, J, Engelhaupt, E, Burrow, ME, and McLachlan, JA | title=Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants | journal=Proceedings of the National Academy of Sciences of the USA | year=2007 | volume=104 | pages=10282–10287 | doi=10.1073/pnas.0611710104]
Pesticides can kill bees and are strongly implicated in
pollinator decline, the loss of species that pollinate plants, including through the mechanism of Colony Collapse Disorder,cite web
author=Hackenberg D |url=http://www.imkerinnen.at/Hauptseite/Menues/News/Brief%20David%20Hackenberg%20307%20engl.doc
title=Letter from David Hackenberg to American growers from March 14, 2007
publisher=Plattform Imkerinnen — Austria
language=English] [cite news
author = Wells, M
title = Vanishing bees threaten US crops
work = www.bbc.co.uk
publisher = "
date = March 11, 2007
url = http://news.bbc.co.uk/2/hi/americas/6438373.stm
accessdate = 2007-09-19
language = English] [cite web
title=Betrayed and sold out – German bee monitoring
language=English] [cite web
title=Schadet imidacloprid den bienen
language=German] in which worker bees from a beehive or
Western honey beecolony abruptly disappear. Application of pesticides to crops that are in bloom can kill honeybees, which act as pollinators. The USDAand USFWSestimate that US farmers lose at least $200 million a year from reduced crop pollination because pesticides applied to fields eliminate about a fifth of honeybee colonies in the US and harm an additional 15%.
Persistent organic pollutants
Persistent organic pollutants (POPs) are compounds that resist degradation and thus remain in the environment for years.Ritter L, Solomon KR, and Forget J, Stemeroff M, and O'Leary C. [http://www.chem.unep.ch/pops/ritter/en/ritteren.pdf Persistent organic pollutants: An Assessment Report on: DDT, Aldrin, Dieldrin, Endrin, Chlordane, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, Polychlorinated Biphenyls, Dioxins and Furans] . Prepared for The International Programme on Chemical Safety (IPCS), within the framework of the Inter-Organization Programme for the Sound Management of Chemicals (IOMC). Retrieved on September 16, 2007.] Some pesticides, including aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, and toxaphene, are considered POPs. POPs have the ability to volatilize and travel great distances through the atmosphere to become deposited in remote regions. The chemicals also have the ability to bioaccumulate and biomagnify, and can bioconcentrate (i.e. become more concentrated) up to 70,000 times their original concentrations. POPs may continue to poison non-target organisms in the environment and increase risk to humans [Centers for Disease Control and Prevention. [http://0-www.cdc.gov.mill1.sjlibrary.org/nceh/indicators/pesticides.htm Pesticides] . cdc.gov. Retrieved on September 15, 2007.] by disruption in the endocrine, reproductive, and immune systems; cancer; neurobehavioral disorders, infertilityand mutagenic effects, although very little is currently known about these chronic effects. Some POPs have been banned, while others continue to be used.
Pesticides inflict extremely widespread damage to
biota, and many countries have acted to discourage pesticide usage through their Biodiversity Action Plans.Fact|date=September 2007
Widespread application of pesticides can eliminate food sources that certain types of animals need, causing the animals to relocate, change their diet, or starve. Poisoning from pesticides can travel up the
food chain; for example, birds can be harmed when they eat insects and worms that have consumed pesticides. Some pesticides can bioaccumulate, or build up to toxic levels in the bodies of organisms that consume them over time, a phenomenon that impacts species high on the food chain especially hard.
The USDA and USFWS estimate that about 20% of the endangered and
threatened speciesin the US are jeopardized by use of pesticides.
Birds are common examples of nontarget organisms that are impacted by pesticide use. Rachel Carson's landmark book "
Silent Spring" dealt with the topic of loss of bird species due to bioaccumulation of pesticides in their tissues. There is evidence that birds are continuing to be harmed by pesticide use. In the farmland of Britain, populations of ten different species of birds have declined by 10 million breeding individuals between 1979 and 1999, a phenomenon thought to have resulted from loss of plant and invertebrate species on which the birds feed.Kerbs JR, Wilson JD, Bradbury RB, and Siriwardena GM (August 12, 1999), [http://www.pmac.net/silent_spring.pdf The second silent spring] . Commentary in "Nature", Volume 400, Pages 611-612.] Throughout Europe, 116 species of birds are now threatened. Reductions in bird populations have been found to be associated with times and areas in which pesticides are used. In another example, some types of fungicides used in peanut farming are only slightly toxic to birds and mammals, but may kill off earthworms, which can in turn reduce populations of the birds and mammals that feed on them.
Some pesticides come in granular form, and birds and other wildlife may eat the granules, mistaking them for grains of food. A few granules of a pesticide is enough to kill a small bird. Palmer, WE, Bromley, PT, and Brandenburg, RL. [http://ipm.ncsu.edu/wildlife/peanuts_wildlife.html Wildlife & pesticides - Peanuts] . North Carolina Cooperative Extension Service. Retrieved on
The herbicide paraquat, when sprayed onto bird eggs, causes growth abnormalities in embryos and reduces the number of chicks that hatch successfully, but most herbicides do not directly cause much harm to birds. Herbicides may endanger bird populations by reducing their habitat.
Fish and other aquatic biota may be harmed by pesticide-contaminated water.Helfrich, LA, Weigmann, DL, Hipkins, P, and Stinson, ER (June 1996), [http://www.ext.vt.edu/pubs/waterquality/420-013/420-013.html#L4 Pesticides and aquatic animals: A guide to reducing impacts on aquatic systems] . Virginia Cooperative Extension. Retrieved on
2007-10-14.] Pesticide surface runoffinto rivers and streams can be highly lethal to aquatic life, sometimes killing all the fish in a particular stream.Toughill K (1999), [http://www.pmac.net/summer-rivers.html The summer the rivers died: Toxic runoff from potato farms is poisoning P.E.I.] Originally published in "Toronto Star Atlantic Canada Bureau". Retrieved on September 17, 2007.] For example, in Montague P.E.I., nine " fish kills" happened in one year: every fish, snake, and snail was killed in a river called Sutherland's Holenear potato farms from which herbicides, insecticides, and fungicides ran off after heavy rains. Pesticide-related fish kills are frequently unreported and likely underestimated.
Application of herbicides to bodies of water can cause fish kills when the dead plants rot and use up the water's oxygen, suffocating the fish. Some herbicides, such as copper sulfite, that are applied to water to kill plants are toxic to fish and other water animals at
concentrations similar to those used to kill the plants. Repeated exposure to sublethal doses of some pesticides can cause physiological and behavioral changes in fish that reduce populations, such as abandonment of nests and broods, decreased immunity to disease, and increased failure to avoid predators.
Pesticides can accumulate in bodies of water to levels that kill off
zooplankton, the main source of food for young fish. [Pesticide Action Network North America (June 4, 1999), [http://www.pmac.net/bird_fish_CA.html Pesticides threaten birds and fish in California] . PANUPS. Retrieved on 2007-09-17.] Pesticides can kill off the insects on which some fish feed, causing the fish to travel farther in search of food and exposing them to greater risk from predators.
Some scientists believe that certain common pesticides already exist at levels capable of killing amphibians in
California."ScienceDaily" (June 25, 2007), [http://www.sciencedaily.com/releases/2007/06/070623213748.htm Breakdown products of widely used pesticides are acutely lethal to amphibians, study finds] . Sciencedaily.com. Retrieved on September 17, 2007.] They warn that the breakdown products of these pesticides can be 10 to 100 times more toxic to amphibians than the original pesticides. Direct contact of sprays of some pesticides (either by drift from nearby applications or accidental or deliberate sprays) can be highly lethal to amphibians. [ [http://www.pitt.edu/~relyea/Roundup.html University of Pittsburgh] ] A Canadian study showed that exposing tadpoles to endosulfan, an organochloridepesticide at levels that are likely to be found in habitats near fields sprayed with the chemical kills the tadpoles and causes behavioral and growth abnormalities. [Raloff, J (September 5, 1998) [http://www.sciencenews.org/pages/sn_arc98/9_5_98/fob5.htm Common pesticide clobbers amphibians] . Science News, Volume 154, Number 10, Page 150. Retrieved on 2007-10-15.]
US scientists have found that some pesticides used in farming disrupt the
nervous systems of frogs, and that use of these pesticides is correlated with a decline in the population of frogs in the Sierra Nevada.Cone M (December 6, 2000), [http://www.pmac.net/wind_borne.html A wind-borne threat to Sierra frogs: A study finds that pesticides used on farms in the San Joaquin Valley damage the nervous systems of amphibians in Yosemite and elsewhere] . "L.A. Times" Retrieved on September 17, 2007.] In the past several decades, decline in amphibian populationshas been occurring all over the world, for unexplained reasons which are thought to be varied but of which pesticides may be a part. Being downwind from agricultural land on which pesticides are used has been linked to the decline in population of threatened frog species in California. ["ScienceDaily" (November 28, 2002), [http://www.sciencedaily.com/releases/2002/11/021126203307.htm More evidence to link pesticide use with amphibian decline] . Sciencedaily.com. Retrieved on September 17, 2007.]
Mixtures of multiple pesticides appear to have a cumulative toxic effect on frogs. Tadpoles from ponds with multiple pesticides present in the water take longer to metamorphose into frogs and are smaller when they do, decreasing their ability to catch prey and avoid predators. "Science Daily" (February 3, 2006), [http://www.sciencedaily.com/releases/2006/02/060202180830.htm Pesticide combinations imperil frogs, probably contribute to amphibian decline] . Sciencedaily.com. Retrieved on
Minnesota, pesticide use has been causally linked to congenital deformities in frogs such as eye, mouth, and limb malformations. [Meersman T (October 25, 1999), [http://www.pmac.net/studies_link.html Studies link frog deformities to pesticides] . "Star Tribune" Retrieved on September 18, 2007.] Researchers in California found that similar deformities in frogs in the US and Canada may have been caused by breakdown products from pesticides which themselves did not pose a threat. ["Science Daily" (May 4, 1998), [http://www.sciencedaily.com/releases/1998/05/980504130605.htm Pesticides linked to widespread cases of deformed frogs] . Sciencedaily.com. Retrieved on 2007-10-12.]
Pests may evolve to become resistant to pesticides. Many pests will initially be very susceptible to pesticides, but some with slight variations in their genetic makeup are resistant and therefore survive to reproduce. Through
natural selection, the pests may eventually become very resistant to the pesticide.
Pest resistance to a pesticide is commonly managed through pesticide rotation, which involves alternating among pesticide classes with different modes of action to delay the onset of or mitigate existing pest resistance.Graeme Murphy (December 1 2005), [http://www.omafra.gov.on.ca/english/crops/hort/news/grower/2005/12gn05a2.htm Resistance Management - Pesticide Rotation] . Ontario Ministry of Agriculture, Food and Rural Affairs. Retrieved on
September 15, 2007.]
Tank mixing pesticides is the combination of two or more pesticides with different modes of action in order to improve individual
pesticide applicationresults and delay the onset of or mitigate existing pest resistance.Fact|date=September 2007
Pest rebound and secondary pest outbreaks
Non-target organisms, organisms that the pesticides are not intended to kill, can be severely impacted by use of the chemicals. In some cases, where a pest insect has some controls from a beneficial
predatoror parasite, an insecticide application can kill both pest and beneficial populations. A study comparing biological pest controland use of pyrethroidinsecticide for diamondback moths, a major cabbagefamily insect pest, showed that the insecticide application created a rebounded pest population due to loss of insect predators, whereas the biocontrol did not show the same effect. [Muckenfuss AE, Shepard BM, Ferrer ER, [http://www.avrdc.org/pdf/90dbm/90DBM02.pdf Natural mortality of diamondback moth in coastal South Carolina] Clemson University, Coastal Research and Education Center.] Likewise, pesticides sprayed in an effort to control adult mosquitoes, may temporarily depress mosquito populations, however they may result in a larger population in the long run by damaging the natural controlling factors. This phenomenon, wherein the population of a pest species rebounds to equal or greater numbers than it had before pesticide use, is called pest resurgence and can be linked to elimination of predators and other natural enemies of the pest.Daly H, Doyen JT, and Purcell AH III (1998), "Introduction to insect biology and diversity", 2nd edition. Oxford University Press. New York, New York. Chapter 14, Pages 279-300.]
Loss of predator species can also lead to a related phenomenon called secondary pest outbreaks, an increase in problems from species which were not originally very damaging pests due to loss of their predators or parasites. An estimated third of the 300 most damaging insects in the US were originally secondary pests and only became a major problem after the use of pesticides. In both pest resurgence and secondary pest outbreaks, the natural enemies have been found to be more susceptible to the pesticides than the pests themselves, in some cases causing the pest population to be higher than it was before the use of pesticide.
Nonpoint source pollution
Pesticide toxicity to bees
* Anderson DW, Hickey JJ, Risebrough RW, Hughes DF, Christensen RE. Significance of chlorinated hydrocarbon residues to breeding pelicans and cormorants. The Canadian Field-Naturalist. 1969; 83:91–112.
* [http://www.pan-uk.org/default.htm Pesticide Action Network UK] - aims to minimize pesticide use
* Streaming online video about efforts to reduce pesticide use in rice in Bangladesh. Windows Media Player [http://www.irri.org/videos/LITE-research.wmv] , Real Player [http://www.irri.org/videos/LITE-research.rm]
* [http://alternatives2toxics.pointinspace.com:80/fmi/iwp/cgi?-db=A2T_HerpDB&-loadframes Reptile Amphibian & Pesticide (RAP) Database]
* [http://extoxnet.orst.edu/pips/ghindex.html EXtension TOXicology NETwork (Extoxnet)] - pesticide information profiles. Environmental and health information broken down by type of pesticide
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