pesticide regulation
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Pesticides are substances that are meant to control pests. This includes herbicide, insecticide,
nematicide A nematicide is a type of chemical pesticide used to kill plant-parasitic nematodes. Nematicides have tended to be broad-spectrum toxicants possessing high volatility or other properties promoting migration through the soil. Aldicarb (Temik), a ca ...
,
molluscicide Molluscicides () – also known as snail baits, snail pellets, or slug pellets – are pesticides against molluscs, which are usually used in agriculture or gardening, in order to control gastropod pests specifically slugs and snails which damag ...
,
piscicide A piscicide is a chemical substance which is poisonous to fish. The primary use for piscicides is to eliminate a dominant species of fish in a body of water, as the first step in attempting to populate the body of water with a different fish. They ...
, avicide,
rodenticide Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, squirrels, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Despi ...
,
bactericide A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on thei ...
,
insect repellent An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and cont ...
,
animal repellent Animal repellents are any things or methods that keep certain animals away from certain objects, areas, people, plants, or other animals. To this end, living organisms emit special semiochemicals naturally; humans purposely make use of some of ...
,
microbicide An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ...
, fungicide, and
lampricide A lampricide is any chemical designed to target the larvae of lampreys in river systems before they develop into parasitic adults. One lampricide is used in the headwaters of Lake Champlain and the Great Lakes to control the sea lamprey (''Petromyz ...
. The most common of these are herbicides which account for approximately 80% of all pesticide use. Most pesticides are intended to serve as plant protection products (also known as crop protection products), which in general, protect plants from
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s, fungi, or
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
s. As an example, the fungus ''
Alternaria solani ''Alternaria solani'' is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tu ...
'' is used to combat the aquatic weed ''
Salvinia ''Salvinia'', a genus in the family Salviniaceae, is a floating fern named in honor of Anton Maria Salvini, a 17th-century Italian scientist. Watermoss is a common name for ''Salvinia''. The genus was published in 1754 by Jean-François Ségui ...
''. In general, a pesticide is a chemical (such as carbamate) or
biological agent A biological agent (also called bio-agent, biological threat agent, biological warfare agent, biological weapon, or bioweapon) is a bacterium, virus, protozoan, parasite, fungus, or toxin that can be used purposefully as a weapon in bioterroris ...
(such as a
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...
,
bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...
, or
fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...
) that deters, incapacitates, kills, or otherwise discourages pests. Target pests can include insects, plant
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s, weeds,
molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estim ...
,
bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s, mammals,
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
, nematodes (roundworms), and microbes that destroy property, cause nuisance, or spread disease, or are disease vectors. Along with these benefits, pesticides also have drawbacks, such as potential toxicity to humans and other species.


Definition

The
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
(FAO) has defined ''pesticide'' as: : any substance or mixture of substances intended for preventing, destroying, or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals, causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances that may be administered to animals for the control of insects, arachnids, or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant, or agent for thinning fruit or preventing the premature fall of fruit. Also used as substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport. Pesticides can be classified by target
organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
(e.g., herbicides, insecticides, fungicides,
rodenticide Rodenticides are chemicals made and sold for the purpose of killing rodents. While commonly referred to as "rat poison", rodenticides are also used to kill mice, squirrels, woodchucks, chipmunks, porcupines, nutria, beavers, and voles. Despi ...
s, and
pediculicide The treatment of human lice is the removal of head lice parasites from human hair. It has been debated and studied for centuries. However, the number of cases of human louse infestations (or pediculosis) has increased worldwide since the mid-1960s, ...
s – see table), chemical structure (e.g., organic, inorganic, synthetic, or biological (biopesticide), although the distinction can sometimes blur), and physical state (e.g. gaseous (fumigant)).
Biopesticide A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships. They are obtained from organisms inclu ...
s include microbial pesticides and biochemical pesticides. Plant-derived pesticides, or " botanicals", have been developing quickly. These include the
pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. I ...
s,
rotenoid Rotenoids are naturally occurring substances containing a cis-fused tetrahydrochromeno ,4-bhromene nucleus. Many have insecticidal activity, such as the prototypical member of the family, rotenone. Rotenoids are related to the isoflavones. Natu ...
s, nicotinoids, and a fourth group that includes strychnine and scilliroside. Many pesticides can be grouped into chemical families. Prominent insecticide families include
organochlorine An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlo ...
s, organophosphates, and carbamates. Organochlorine hydrocarbons (e.g.,
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
) could be separated into dichlorodiphenyl ethanes, cyclodiene compounds, and other related compounds. They operate by disrupting the sodium/potassium balance of the nerve fiber, forcing the nerve to transmit continuously. Their toxicities vary greatly, but they have been phased out because of their persistence and potential to
bioaccumulate Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
. Organophosphate and carbamates largely replaced organochlorines. Both operate through inhibiting the enzyme acetylcholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely and causing a variety of symptoms such as weakness or paralysis. Organophosphates are quite toxic to vertebrates and have in some cases been replaced by less toxic carbamates. Thiocarbamate and dithiocarbamates are subclasses of carbamates. Prominent families of herbicides include phenoxy and benzoic acid herbicides (e.g. 2,4-D), triazines (e.g.,
atrazine Atrazine is a chlorinated herbicide of the triazine class. It is used to prevent pre-emergence broadleaf weeds in crops such as maize (corn), soybean and sugarcane and on turf, such as golf courses and residential lawns. Atrazine's primary manu ...
), ureas (e.g., diuron), and Chloroacetanilide (e.g., alachlor). Phenoxy compounds tend to selectively kill broad-leaf weeds rather than grasses. The phenoxy and benzoic acid herbicides function similar to plant growth hormones, and grow cells without normal cell division, crushing the plant's nutrient transport system. Triazines interfere with photosynthesis. Many commonly used pesticides are not included in these families, including
glyphosate Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshik ...
. The application of pest control agents is usually carried out by dispersing the chemical in an (often hydrocarbon-based)
solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...
- surfactant system to give a homogeneous preparation. A
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...
lethality study performed in 1977 demonstrated that a particular pesticide did not increase the lethality of the virus. Combinations that included surfactants and the solvent clearly showed that pretreatment with them markedly increased the viral lethality in the test mice. Pesticides can be classified based upon their biological mechanism function or application method. Most pesticides work by poisoning pests. A systemic pesticide moves inside a plant following absorption by the plant. With insecticides and most fungicides, this movement is usually upward (through the
xylem Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from ...
) and outward. Increased efficiency may be a result. Systemic insecticides, which poison pollen and nectar in the
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s, may kill bees and other needed pollinators. In 2010, the development of a new class of fungicides called paldoxins was announced. These work by taking advantage of natural defense chemicals released by plants called
phytoalexins Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined, not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants th ...
, which fungi then detoxify using enzymes. The paldoxins inhibit the fungi's detoxification enzymes. They are believed to be safer and greener.


History

Since before 2000 BC, humans have utilized pesticides to protect their crops. The first known pesticide was elemental sulfur dusting used in ancient Sumer about 4,500 years ago in ancient Mesopotamia. By the 15th century, toxic chemicals such as
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...
, mercury, and
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
were being applied to crops to kill pests. In the 17th century,
nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
was extracted from
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
leaves for use as an insecticide. The 19th century saw the introduction of two more natural pesticides,
pyrethrum ''Pyrethrum'' was a genus of several Old World plants now classified as ''Chrysanthemum'' or ''Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly inclu ...
, which is derived from chrysanthemums, and
rotenone Rotenone is an odorless, colorless, crystalline isoflavone used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant, and the roots of several mem ...
, which is derived from the roots of tropical
vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...
s. Until the 1950s, arsenic-based pesticides were dominant. Paul Müller discovered that
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
was a very effective insecticide. Chlorinates such as DDT were dominant, but they were replaced in the U.S. by organophosphates and carbamates by 1975. Since then,
pyrethrin The pyrethrins are a class of organic compounds normally derived from '' Chrysanthemum cinerariifolium'' that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and i ...
compounds have become the dominant insecticide. Herbicides became common in the 1960s, led by "triazine and other nitrogen-based compounds, carboxylic acids such as 2,4-dichlorophenoxyacetic acid, and glyphosate". The first legislation providing federal authority for regulating pesticides was enacted in 1910. During the 1940s, manufacturers produced large amounts of synthetic pesticides and their use became widespread. Before the first World War, Germany was the world's leading chemical industry and exported most of the dyes and other chemicals that were used in the United States. War implemented tariffs that stimulated the growth of the chemical industry in the U.S., which made chemistry a prestigious occupation as this industry expanded and became profitable. Money and ideas flowed back from Europe after the U.S. entered WWI, changing the way Americans interacted with themselves and nature, and the industrialization of war hastened the industrialization of pest control. Some sources consider the 1940s and 1950s to have been the start of the "pesticide era." Although the U.S. Environmental Protection Agency was established in 1970 and amendments to the pesticide law in 1972, pesticide use has increased 50-fold since 1950 and 2.3 million tonnes (2.5 million short tons) of industrial pesticides are now used each year. Seventy-five percent of all pesticides in the world are used in developed countries, but use in developing countries is increasing. A study of USA pesticide use trends through 1997 was published in 2003 by the National Science Foundation's Center for Integrated Pest Management. In the 1960s, it was discovered that DDT was preventing many fish-eating birds from reproducing, which was a serious threat to
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
.
Rachel Carson Rachel Louise Carson (May 27, 1907 – April 14, 1964) was an American marine biologist, writer, and conservationist whose influential book '' Silent Spring'' (1962) and other writings are credited with advancing the global environmental ...
wrote the best-selling book ''
Silent Spring ''Silent Spring'' is an environmental science book by Rachel Carson. Published on September 27, 1962, the book documented the environmental harm caused by the indiscriminate use of pesticides. Carson accused the chemical industry of spreading d ...
'' about biological magnification. The agricultural use of DDT is now banned under the
Stockholm Convention Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organic ...
on Persistent Organic Pollutants, but it is still used in some developing nations to prevent
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
and other tropical diseases by spraying on interior walls to kill or repel mosquitoes.


Development

Available pesticides are not sufficient and new developments are needed. Continued research into the basic biology of pests may identify new vulnerabilities and produce new pesticides; it may also yield pesticides with better financial and environmental characteristics than those presently used. Plant-derived pesticides, or "botanicals", have been developing quickly. These include the
pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. I ...
s,
rotenoid Rotenoids are naturally occurring substances containing a cis-fused tetrahydrochromeno ,4-bhromene nucleus. Many have insecticidal activity, such as the prototypical member of the family, rotenone. Rotenoids are related to the isoflavones. Natu ...
s, nicotinoids, and a fourth group that includes strychnine and scilliroside. In 2010, the development of a new class of fungicides called paldoxins was announced. These work by taking advantage of natural defense chemicals released by plants called
phytoalexins Phytoalexins are antimicrobial substances, some of which are antioxidative as well. They are defined, not by their having any particular chemical structure or character, but by the fact that they are defensively synthesized ''de novo'' by plants th ...
, which fungi then detoxify using enzymes. The paldoxins inhibit the fungi's detoxification enzymes. They are believed to be safer and greener.
Fungicide resistance Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...
is increasing the proportion of inactive enantiomers in fungicide applications: The evolution of resistance necessitates research and discovery of new
active ingredient An active ingredient is any ingredient that provides biologically active or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease or to affect the structure or any function of the body of humans or animals. The ...
s, which trends away from already-discovered classes and toward more complex chemical structures. These tend to have more chiral centers more often which means more offproducts during synthesis. . Insecticide development is being discouraged and slowed down by public sentiment surrounding the worldwide
colony collapse disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. While s ...
crisis. Although CCD is a serious problem, there are indications that other facts are involved, especially Cox-Foster et al. 2007's discovery that a virus is substantially to blame. (See also.) Public concern has risen irrespective of the facts, and based instead on emotion and agrochemical research companies face a challenge of image and perception. Partnering with
agricultural extension Agricultural extension is the application of scientific research and new knowledge to agricultural practices through farmer education. The field of 'extension' now encompasses a wider range of communication and learning activities organized for r ...
s could help to remedy some of that and get pesticide research back on track.


Uses

Pesticides are used to control organisms that are considered to be harmful, or pernicious to their surroundings. For example, they are used to kill
mosquitoes Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small Diptera, flies within the family Culicidae (from the Latin ''culex'' meaning "gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish ...
that can transmit potentially deadly diseases like
West Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family '' Flaviviridae'', from the genus '' Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The v ...
,
yellow fever Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains – particularly in the back – and headaches. Symptoms typically improve within five days. ...
, and
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
. They can also kill bees,
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
s or
ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...
s that can cause allergic reactions. Insecticides can protect animals from illnesses that can be caused by
parasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
such as
flea Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, a ...
s. Pesticides can prevent sickness in humans that could be caused by
mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...
y food or diseased produce. Herbicides can be used to clear roadside weeds, trees, and brush. They can also kill invasive
weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s that may cause environmental damage. Herbicides are commonly applied in ponds and lakes to control algae and plants such as water grasses that can interfere with activities like swimming and fishing and cause the water to look or smell unpleasant. Uncontrolled pests such as termites and mold can damage structures such as houses. Pesticides are used in grocery stores and food storage facilities to manage rodents and insects that infest food such as grain. Each use of a pesticide carries some associated risk. Proper pesticide use decreases these associated risks to a level deemed acceptable by pesticide regulatory agencies such as the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
(EPA) and the Pest Management Regulatory Agency (PMRA) of Canada.
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
, sprayed on the walls of houses, is an organochlorine that has been used to fight
malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
since the 1950s. Recent policy statements by the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
have given stronger support to this approach. It and other organochlorine pesticides have been banned in most countries worldwide because of their persistence in the environment and human toxicity. DDT use is not always effective, as resistance to DDT was identified in Africa as early as 1955, and by 1972 nineteen species of mosquito worldwide were resistant to DDT.


Amount used

In 2006 and 2007, the world used approximately of pesticides, with herbicides constituting the biggest part of the world pesticide use at 40%, followed by insecticides (17%) and fungicides (10%). In 2006 and 2007 the U.S. used approximately of pesticides, accounting for 22% of the world total, including of conventional pesticides, which are used in the agricultural sector (80% of conventional pesticide use) as well as the industrial, commercial, governmental and home & garden sectors. The state of California alone used 117 million pounds. Pesticides are also found in majority of U.S. households with 88 million out of the 121.1 million households indicating that they use some form of pesticide in 2012. As of 2007, there were more than 1,055 active ingredients registered as pesticides, which yield over 20,000 pesticide products that are marketed in the United States. The US used some 1 kg (2.2 pounds) per
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100- metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is ...
of
arable land Arable land (from the la, arabilis, "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for th ...
compared with: 4.7 kg in China, 1.3 kg in the UK, 0.1 kg in
Cameroon Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
, 5.9 kg in Japan and 2.5 kg in Italy. Insecticide use in the US has declined by more than half since 1980 (0.6%/yr), mostly due to the near phase-out of organophosphates. In corn fields, the decline was even steeper, due to the switchover to
transgenic A transgene is a gene that has been transferred naturally, or by any of a number of genetic engineering techniques, from one organism to another. The introduction of a transgene, in a process known as transgenesis, has the potential to change the ...
Bt corn. For the global market of
crop protection Crop protection is the science and practice of managing plant diseases, weeds, and other pests (both vertebrate and invertebrate) that damage crops and forestry. Crops include field crops (maize, wheat, rice, etc.), vegetable crops ( potatoes, ca ...
products, market analysts forecast revenues of over 52 billion US$ in 2019.


Benefits

Pesticides can save farmers' money by preventing crop losses to insects and other pests; in the U.S., farmers get an estimated fourfold return on money they spend on pesticides. One study found that not using pesticides reduced crop yields by about 10%. Another study, conducted in 1999, found that a ban on pesticides in the United States may result in a rise of
food prices Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices have an impact on producers and consumers of food. Price levels depend on the food production process, including food marketing ...
, loss of jobs, and an increase in world hunger. There are two levels of benefits for pesticide use, primary and secondary. Primary benefits are direct gains from the use of pesticides and secondary benefits are effects that are more long-term.


Biological

Controlling pests and plant disease vectors *Improved crop yields *Improved crop/livestock quality * Invasive species controlled Controlling human/livestock disease vectors and nuisance organisms *Human lives saved and disease reduced. Diseases controlled include malaria, with millions of lives having been saved or enhanced with the use of
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
alone. *Animal lives saved and disease reduced Controlling organisms that harm other human activities and structures *Drivers view unobstructed *Tree/brush/leaf hazards prevented *Wooden structures protected


Monetary

In one study, it was estimated that for every dollar ($1) that is spent on pesticides for crops can yield up to four dollars ($4) in crops saved. This means based that, on the amount of money spent per year on pesticides, $10 billion, there is an additional $40 billion savings in crop that would be lost due to damage by insects and weeds. In general, farmers benefit from having an increase in crop yield and from being able to grow a variety of crops throughout the year. Consumers of agricultural products also benefit from being able to afford the vast quantities of produce available year-round. Post- WWII conditions caused the pesticide industry to flourish for several reasons including the growing middle class and the invention of cheap tractor-drawn spraying equipment. By the 1980s the demand for pesticides had dropped due to farmers struggling financially and the market for chemicals becoming oversaturated. There were also new costs for producing pesticides due to the strict EPA laws surrounding the chemicals. The modern pesticide market is seven billion dollars and is growing 4% per year due to the invention of the lawn and the stigma surrounding the untamed yard.


Costs

On the cost side of pesticide use there can be costs to the environment, costs to human health, as well as costs of the development and research of new pesticides.


Health effects

Pesticides may cause acute and delayed health effects in people who are exposed. Pesticide exposure can cause a variety of adverse health effects, ranging from simple irritation of the skin and eyes to more severe effects such as affecting the nervous system, hearing, mimicking hormones causing reproductive problems, and also causing cancer. A 2007 systematic review found that "most studies on
non-Hodgkin lymphoma Non-Hodgkin lymphoma (NHL), also known as non-Hodgkin's lymphoma, is a group of blood cancers that includes all types of lymphomas except Hodgkin lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tirednes ...
and
leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ...
showed positive associations with pesticide exposure" and thus concluded that cosmetic use of pesticides should be decreased. There is substantial evidence of associations between organophosphate insecticide exposures and neurobehavioral alterations. Limited evidence also exists for other negative outcomes from pesticide exposure including neurological,
birth defects A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
, and
fetal death Perinatal mortality (PNM) refers to the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. Variations in the precise definition of the perinatal mortality exist, specifically concerning the issue of inclusion o ...
. The American Academy of Pediatrics recommends limiting exposure of children to pesticides and using safer alternatives: Owing to inadequate regulation and safety precautions, 99% of pesticide-related deaths occur in developing countries that account for only 25% of pesticide usage. One study found pesticide self-poisoning the method of choice in one third of suicides worldwide, and recommended, among other things, more restrictions on the types of pesticides that are most harmful to humans. A 2014 epidemiological review found associations between autism and exposure to certain pesticides, but noted that the available evidence was insufficient to conclude that the relationship was causal.


Occupational exposure among agricultural workers

The World Health Organization and the
UN Environment Programme The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on th ...
estimate that 3 million agricultural workers in the developing world experience severe poisoning from pesticides each year, resulting in 18,000 deaths. According to one study, as many as 25 million workers in developing countries may suffer mild pesticide poisoning yearly. Other occupational exposures besides agricultural workers, including pet groomers, groundskeepers, and fumigators, may also put individuals at risk of health effects from pesticides. Pesticide use is widespread in
Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived f ...
, as around US$3 billion are spent each year in the region. Records indicate an increase in the frequency of pesticide poisonings over the past two decades. The most common incidents of pesticide poisoning is thought to result from exposure to organophosphate and carbamate insecticides. At-home pesticide use, use of unregulated products, and the role of undocumented workers within the agricultural industry makes characterizing true pesticide exposure a challenge. It is estimated that 50–80% of pesticide poisoning cases are unreported. Underreporting of pesticide poisoning is especially common in areas where agricultural workers are less likely to seek care from a healthcare facility that may be monitoring or tracking the incidence of acute poisoning. The extent of unintentional pesticide poisoning may be much greater than available data suggest, particularly among developing countries. Globally, agriculture and food production remain one of the largest industries. In East Africa, the agricultural industry represents one of the largest sectors of the economy, with nearly 80% of its population relying on agriculture for income. Farmers in these communities rely on pesticide products to maintain high crop yields. Some East Africa governments are shifting to corporate farming, and opportunities for foreign conglomerates to operate commercial farms have led to more accessible research on pesticide use and exposure among workers. In other areas where large proportions of the population rely on subsistence, small-scale farming, estimating pesticide use and exposure is more difficult.


Pesticide poisoning

Pesticides may exhibit toxic effects on
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
and other non-target species, the severity of which depends on the frequency and magnitude of exposure. Toxicity also depends on the rate of absorption, distribution within the body, metabolism, and elimination of compounds from the body. Commonly used pesticides like organophosphates and carbamates act by inhibiting acetylcholinesterase activity, which prevents the breakdown of acetylcholine at the neural synapse. Excess acetylcholine can lead to symptoms like muscle cramps or tremors, confusion, dizziness and nausea. Studies show that farm workers in Ethiopia, Kenya, and Zimbabwe have decreased concentrations of plasma acetylcholinesterase, the enzyme responsible for breaking down acetylcholine acting on synapses throughout the
nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...
. Other studies in Ethiopia have observed reduced respiratory function among farm workers who spray crops with pesticides. Numerous exposure pathways for farm workers increase the risk of pesticide poisoning, including dermal absorption walking through fields and applying products, as well as inhalation exposure.


Measuring exposure to pesticides

There are multiple approaches to measuring a person's exposure to pesticides, each of which provides an estimate of an individual's internal dose. Two broad approaches include measuring biomarkers and markers of biological effect. The former involves taking direct measurement of the parent compound or its metabolites in various types of media: urine, blood, serum. Biomarkers may include a direct measurement of the compound in the body before it's been biotransformed during metabolism. Other suitable biomarkers may include the metabolites of the parent compound after they've been biotransformed during metabolism. Toxicokinetic data can provide more detailed information on how quickly the compound is metabolized and eliminated from the body, and provide insights into the timing of exposure. Markers of biological effect provide an estimation of exposure based on cellular activities related to the mechanism of action. For example, many studies investigating exposure to pesticides often involve the quantification of the acetylcholinesterase enzyme at the neural synapse to determine the magnitude of the inhibitory effect of organophosphate and carbamate pesticides. Another method of quantifying exposure involves measuring, at the molecular level, the amount of pesticide interacting with the site of action. These methods are more commonly used for occupational exposures where the mechanism of action is better understood, as described by WHO guidelines published in "Biological Monitoring of Chemical Exposure in the Workplace". Better understanding of how pesticides elicit their toxic effects is needed before this method of exposure assessment can be applied to occupational exposure of agricultural workers. Alternative methods to assess exposure include questionnaires to discern from participants whether they are experiencing symptoms associated with pesticide poisoning. Self-reported symptoms may include headaches, dizziness, nausea, joint pain, or respiratory symptoms.


= Challenges in assessing pesticide exposure

= Multiple challenges exist in assessing exposure to pesticides in the general population, and many others that are specific to occupational exposures of agricultural workers. Beyond farm workers, estimating exposure to family members and children presents additional challenges, and may occur through "take-home" exposure from pesticide residues collected on clothing or equipment belonging to parent farm workers and inadvertently brought into the home. Children may also be exposed to pesticides prenatally from mothers who are exposed to pesticides during pregnancy. Characterizing children's exposure resulting from drift of airborne and spray application of pesticides is similarly challenging, yet well documented in developing countries. Because of critical development periods of the fetus and newborn children, these non-working populations are more vulnerable to the effects of pesticides, and may be at increased risk of developing neurocognitive effects and impaired development. While measuring biomarkers or markers of biological effects may provide more accurate estimates of exposure, collecting these data in the field is often impractical and many methods are not sensitive enough to detect low-level concentrations. Rapid cholinesterase test kits exist to collect blood samples in the field. Conducting large scale assessments of agricultural workers in remote regions of developing countries makes the implementation of these kits a challenge. The cholinesterase assay is a useful clinical tool to assess individual exposure and acute toxicity. Considerable variability in baseline enzyme activity among individuals makes it difficult to compare field measurements of cholinesterase activity to a
reference dose A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose (abbreviated RfD) as: es ...
to determine health risk associated with exposure. Another challenge researchers face in deriving a
reference dose A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose (abbreviated RfD) as: es ...
is identifying health endpoints that are relevant to exposure. More epidemiological research is needed to identify critical health endpoints, particularly among populations who are occupationally exposed.


Prevention

Minimizing harmful exposure to pesticides can be achieved by proper use of personal protective equipment, adequate reentry times into recently sprayed areas, and effective product labeling for hazardous substances as per
FIFRA The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) is a United States federal law that set up the basic U.S. system of pesticide regulation to protect applicators, consumers, and the environment. It is administered and regulated by th ...
regulations. Training high-risk populations, including agricultural workers, on the proper use and storage of pesticides, can reduce the incidence of acute pesticide poisoning and potential chronic health effects associated with exposure. Continued research into the human toxic health effects of pesticides serves as a basis for relevant policies and enforceable standards that are health protective to all populations.


Environmental effects

Pesticide use raises a number of environmental concerns.Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil.
Pesticide drift Pesticide drift refers to the unintentional diffusion of pesticides and the potential negative effects of pesticide application, including off-target contamination due to spray drift as well as runoff from plants or soil. This can lead to damag ...
occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of
water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. ...
, and some pesticides are
persistent organic pollutants Persistent organic pollutants (POPs), sometimes known as "forever chemicals", are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. They are toxic chemicals that adversel ...
and contribute to
soil Soil, also commonly referred to as earth or dirt Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Debri ...
and flower (pollen, nectar) contamination. Furthermore, pesticide use can adversely impact neighboring agricultural activity, as pests themselves drift to and harm nearby crops that have no pesticide used on them. In addition, pesticide use reduces
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
, contributes to
pollinator decline Pollinator decline is the reduction in abundance of insect and other animal pollinators in many ecosystems worldwide that began being recorded at the end of the 20th century. Multiple lines of evidence exist for the reduction of wild pollinator ...
, destroys habitat (especially for birds), and threatens endangered species. Pests can develop a resistance to the pesticide (
pesticide resistance Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens su ...
), necessitating a new pesticide. Alternatively a greater dose of the pesticide can be used to counteract the resistance, although this will cause a worsening of the ambient pollution problem. The Stockholm Convention on Persistent Organic Pollutants, listed 9 of the 12 most dangerous and persistent
organic chemicals In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The s ...
that were (now mostly obsolete) organochlorine pesticides. Since chlorinated hydrocarbon pesticides dissolve in fats and are not excreted, organisms tend to retain them almost indefinitely. Biological magnification is the process whereby these chlorinated hydrocarbons (pesticides) are more concentrated at each level of the food chain. Among marine animals, pesticide concentrations are higher in carnivorous fishes, and even more so in the fish-eating birds and mammals at the top of the
ecological pyramid An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bioproductivity at each trophic level in a given ecosystem. A ''pyramid of ...
. Global distillation is the process whereby pesticides are transported from warmer to colder regions of the Earth, in particular the Poles and mountain tops. Pesticides that evaporate into the atmosphere at relatively high temperature can be carried considerable distances (thousands of kilometers) by the wind to an area of lower temperature, where they condense and are carried back to the ground in rain or snow. In order to reduce negative impacts, it is desirable that pesticides be degradable or at least quickly deactivated in the environment. Such loss of activity or toxicity of pesticides is due to both innate chemical properties of the compounds and environmental processes or conditions. For example, the presence of
halogens The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group i ...
within a chemical structure often slows down degradation in an aerobic environment.
Adsorption Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which ...
to soil may retard pesticide movement, but also may reduce
bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...
to microbial degraders.


Economics

In one study, the human health and environmental costs due to pesticides in the United States was estimated to be $9.6 billion: offset by about $40 billion in increased agricultural production. Additional costs include the registration process and the cost of purchasing pesticides: which are typically borne by agrichemical companies and farmers respectively. The registration process can take several years to complete (there are 70 different types of field tests) and can cost $50–70 million for a single pesticide. At the beginning of the 21st century, the United States spent approximately $10 billion on pesticides annually.


Resistance

The use of pesticides inherently entails the risk of resistance developing. Various techniques and procedures of
pesticide application Pesticide application refers to the practical way in which pesticides (including herbicides, fungicides, insecticides, or nematode control agents) are delivered to their ''biological targets'' (''e.g.'' pest organism, crop or other plant). Publ ...
can slow the development of resistance, as can some natural features of the target population and surrounding environment.


Alternatives

Alternatives to pesticides are available and include methods of cultivation, use of biological pest controls (such as pheromones and microbial pesticides), genetic engineering (mostly of crops), and methods of interfering with insect breeding. Application of composted yard waste has also been used as a way of controlling pests. These methods are becoming increasingly popular and often are safer than traditional chemical pesticides. In addition, EPA is registering reduced-risk pesticides in increasing numbers. ;Cultivation practices Cultivation practices include
polyculture In agriculture, polyculture is the practice of growing more than one crop species in the same space, at the same time. In doing this, polyculture attempts to mimic the diversity of natural ecosystems. Polyculture is the opposite of monoculture, i ...
(growing multiple types of plants),
crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant ...
, planting crops in areas where the pests that damage them do not live, timing planting according to when pests will be least problematic, and use of
trap crop A trap crop is a plant that attracts agricultural pests, usually insects, away from nearby crops. This form of companion planting can save the main crop from decimation by pests without the use of pesticides. /sup> A trap crop is used for attracti ...
s that attract pests away from the real crop. Trap crops have successfully controlled pests in some commercial agricultural systems while reducing pesticide usage. In other systems, trap crops can fail to reduce pest densities at a commercial scale, even when the trap crop works in controlled experiments. ;Use of other organisms Release of other organisms that fight the pest is another example of an alternative to pesticide use. These organisms can include natural
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s or
parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
s of the pests. Biological pesticides based on
entomopathogenic fungi An entomopathogenic fungus is a fungus that can kill or seriously disable insects. Typical life cycle These fungi usually attach to the external body surface of insects in the form of microscopic spores (usually asexual, mitosporic spores also ...
,
bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
and
virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...
es causing disease in the pest species can also be used. ;Biological control engineering Interfering with insects' reproduction can be accomplished by sterilizing males of the target species and releasing them, so that they mate with females but do not produce offspring. This technique was first used on the screwworm fly in 1958 and has since been used with the
medfly ''Ceratitis capitata'', commonly known as the Mediterranean fruit fly or medfly, is a yellow-and-brown fly native to sub-Saharan Africa. It has no near relatives in the Western Hemisphere and is considered to be one of the most destructive fr ...
, the
tsetse fly Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glos ...
, and the
gypsy moth ''Lymantria dispar'', also known as the gypsy moth or the spongy moth, is a species of moth in the family Erebidae. ''Lymantria dispar'' is subdivided into several subspecies, with subspecies such as ''L. d. dispar'' and ''L. d. japonica'' bei ...
. This is a costly and slow approach that only works on some types of insects. ;Other Other alternatives include "laserweeding" – the use of novel
agricultural robot An agricultural robot is a robot deployed for agricultural purposes. The main area of application of robots in agriculture today is at the harvesting stage. Emerging applications of robots or drones in agriculture include weed control, cloud s ...
s for
weed control Weed control is a type of pest control, which attempts to stop or reduce growth of weeds, especially noxious weeds, with the aim of reducing their competition with desired flora and fauna including domesticated plants and livestock, and in n ...
using lasers.


Push pull strategy

The term "push-pull" was established in 1987 as an approach for
integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates both chemical and non-chemical practices for economic control of pests. IPM aims to suppress pest populations below the econ ...
(IPM). This strategy uses a mixture of behavior-modifying stimuli to manipulate the distribution and abundance of insects. "Push" means the insects are repelled or deterred away from whatever resource is being protected. "Pull" means that certain stimuli (semiochemical stimuli, pheromones, food additives, visual stimuli, genetically altered plants, etc.) are used to attract pests to trap crops where they will be killed. There are numerous different components involved in order to implement a Push-Pull Strategy in IPM. Many case studies testing the effectiveness of the push-pull approach have been done across the world. The most successful push-pull strategy was developed in Africa for subsistence farming. Another successful case study was performed on the control of '' Helicoverpa'' in cotton crops in Australia. In Europe, the Middle East, and the United States, push-pull strategies were successfully used in the controlling of '' Sitona lineatus'' in bean fields. Some advantages of using the push-pull method are less use of chemical or biological materials and better protection against insect habituation to this control method. Some disadvantages of the push-pull strategy are that if there is a lack of appropriate knowledge of the behavioral and chemical ecology of the host-pest interactions then this method becomes unreliable. Furthermore, because the push-pull method is not a very popular method of IPM operational and registration costs are higher.


Effectiveness

Some evidence shows that alternatives to pesticides can be equally effective as the use of chemicals. A study of
Maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
fields in northern Florida found that the application of composted yard waste with high carbon to nitrogen ratio to agricultural fields was highly effective at reducing the population of plant-parasitic nematodes and increasing crop yield, with yield increases ranging from 10% to 212%; the observed effects were long-term, often not appearing until the third season of the study. Additional
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...
nutrition protects some horticultural crops against
fungal diseases Pathogenic fungi are fungi that cause disease in humans or other organisms. Approximately 300 fungi are known to be pathogenic to humans. Markedly more fungi are known to be pathogenic to plant life than those of the animal kingdom. The study of fu ...
almost completely, while insufficient silicon sometimes leads to severe infection even when fungicides are used. Pesticide resistance is increasing and that may make alternatives more attractive.


Types

Pesticides are often referred to according to the type of pest they control. Pesticides can also be considered as either biodegradable pesticides, which will be broken down by microbes and other living beings into harmless compounds, or persistent pesticides, which may take months or years before they are broken down: it was the persistence of DDT, for example, which led to its accumulation in the food chain and its killing of birds of prey at the top of the food chain. Another way to think about pesticides is to consider those that are chemical pesticides are derived from a common source or production method.


Insecticides

Neonicotinoids Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. The neonicotinoid family includes acetamiprid, clothianidin, din ...
are a class of neuro-active insecticides chemically similar to
nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...
.
Imidacloprid Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system ...
, of the neonicotinoid family, is the most widely used insecticide in the world. In the late 1990s neonicotinoids came under increasing scrutiny over their environmental impact and were linked in a range of studies to adverse ecological effects, including honey-bee
colony collapse disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee colony disappear, leaving behind a queen, plenty of food, and a few nurse bees to care for the remaining immature bees. While s ...
(CCD) and loss of birds due to a reduction in insect populations. In 2013, the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
and a few non EU countries restricted the use of certain neonicotinoids. Organophosphate and carbamate insecticides have a similar mode of action. They affect the nervous system of target pests (and non-target organisms) by disrupting acetylcholinesterase activity, the enzyme that regulates acetylcholine, at nerve synapses. This inhibition causes an increase in synaptic acetylcholine and overstimulation of the parasympathetic nervous system. Many of these insecticides, first developed in the mid 20th century, are very poisonous. Although commonly used in the past, many older chemicals have been removed from the market due to their health and environmental effects (''e.g.''
DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...
,
chlordane Chlordane, or chlordan, is an organochlorine compound that was used as a pesticide. It is a white solid. In the United States, chlordane was used for termite-treatment of approximately 30 million homes until it was banned in 1988. Chlordane was ...
, and
toxaphene Toxaphene was an insecticide used primarily for cotton in the southern United States during the late 1960s and the 1970s. Toxaphene is a mixture of over 670 different chemicals and is produced by reacting chlorine gas with camphene. It can be mo ...
). Many organophosphates do not persist in the environment.
Pyrethroid A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums (''Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. I ...
insecticides were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. They have been modified to increase their stability in the environment. Some synthetic pyrethroids are toxic to the nervous system.


Herbicides

A number of sulfonylureas have been commercialized for weed control, including: amidosulfuron, flazasulfuron, metsulfuron-methyl, rimsulfuron, sulfometuron-methyl, terbacil, nicosulfuron, and triflusulfuron-methyl. These are broad-spectrum herbicides that kill plants weeds or pests by inhibiting the enzyme
acetolactate synthase The acetolactate synthase (ALS) enzyme (also known as acetohydroxy acid or acetohydroxyacid synthase, abbr. AHAS) is a protein found in plants and micro-organisms. ALS catalyzes the first step in the synthesis of the branched-chain amino acids ( ...
. In the 1960s, more than crop protection chemical was typically applied, while sulfonylureates allow as little as 1% as much material to achieve the same effect.


Biopesticides

Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered biopesticides. Biopesticides fall into three major classes: * Microbial pesticides which consist of bacteria,
entomopathogenic fungi An entomopathogenic fungus is a fungus that can kill or seriously disable insects. Typical life cycle These fungi usually attach to the external body surface of insects in the form of microscopic spores (usually asexual, mitosporic spores also ...
or viruses (and sometimes includes the metabolites that bacteria or fungi produce). Entomopathogenic nematodes are also often classed as microbial pesticides, even though they are multi-cellular. * Biochemical pesticides or herbal pesticides are naturally occurring substances that control (or monitor in the case of
pheromones A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
) pests and microbial diseases. * Plant-incorporated protectants (PIPs) have genetic material from other species incorporated into their genetic material (''i.e.''
GM crop GM or Gm may refer to: Companies * General Motors, US automobile manufacturing company which was founded in 1908 ** Motors Liquidation Company, the US automobile manufacturing company known as General Motors Corporation from 1916 to 2009 * ...
s). Their use is controversial, especially in many European countries.


By pest type

Pesticides that are related to the type of pests are:


Further types

The term pesticide also includes these substances: *
Defoliant A defoliant is any herbicidal chemical sprayed or dusted on plants to cause their leaves to fall off. Defoliants are widely used for the selective removal of weeds in managing croplands and lawns. Worldwide use of defoliants, along with the ...
s: Cause leaves or other foliage to drop from a plant, usually to facilitate harvest. *
Desiccants A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants ...
: Promote drying of living tissues, such as unwanted plant tops. * Insect growth regulators: Disrupt the molting, maturity from pupal stage to adult, or other life processes of insects. *
Plant growth regulator Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, ...
s: Substances (excluding fertilizers or other plant nutrients) that alter the expected growth, flowering, or reproduction rate of plants. *Soil sterilant: a chemical that temporarily or permanently prevents the growth of all plants and animals, depending on the chemical.
Soil Soil, also commonly referred to as earth or dirt Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Debri ...
sterilants must be registered as pesticides. * Wood preservatives: They are used to make wood resistant to insects, fungus, and other pests. *
Gene drive A gene drive is a natural process and technology of genetic engineering that propagates a particular suite of genes throughout a population by altering the probability that a specific allele will be transmitted to offspring (instead of the Mende ...
s, a complex genetic mechanism which can be embedded into the genetic material of the target species itself. Instead of killing the target individual it can, kill, eliminate the reproduction of, or suppress the reproductive rate of its descendants. This changes the target population in a more pervasive way and has few or no off-target effects.


Regulation


International

In many countries, pesticides must be approved for sale and use by a government agency. Worldwide, 85% of countries have pesticide legislation for the proper storage of pesticides and 51% include provisions to ensure proper disposal of all obsolete pesticides. In Europe, EU legislation has been approved banning the use of highly toxic pesticides including those that are
carcinogenic A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
,
mutagenic In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer i ...
or toxic to reproduction, those that are endocrine-disrupting, and those that are persistent, bioaccumulative and toxic (PBT) or very persistent and very bioaccumulative (vPvB) and measures have been approved to improve the general safety of pesticides across all EU member states. Though pesticide regulations differ from country to country, pesticides, and products on which they were used are traded across international borders. To deal with inconsistencies in regulations among countries, delegates to a conference of the United Nations
Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
adopted an International Code of Conduct on the Distribution and Use of Pesticides in 1985 to create voluntary standards of pesticide regulation for different countries. The Code was updated in 1998 and 2002. The FAO claims that the code has raised awareness about pesticide hazards and decreased the number of countries without restrictions on pesticide use. Three other efforts to improve regulation of international pesticide trade are the United Nations London Guidelines for the Exchange of Information on Chemicals in International Trade and the United Nations Codex Alimentarius Commission. The former seeks to implement procedures for ensuring that prior informed consent exists between countries buying and selling pesticides, while the latter seeks to create uniform standards for maximum levels of pesticide residues among participating countries. Pesticides safety education and pesticide applicator regulation are designed to protect the public from
pesticide misuse Under United States law, pesticide misuse is considered to be the use of a pesticide in a way that violates laws regulating their use or endangers humans or the environment; many of these regulations are laid out in the Federal Insecticide, Fungic ...
, but do not eliminate all misuse. Reducing the use of pesticides and choosing less toxic pesticides may reduce risks placed on society and the environment from pesticide use.
Integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates both chemical and non-chemical practices for economic control of pests. IPM aims to suppress pest populations below the econ ...
, the use of multiple approaches to control pests, is becoming widespread and has been used with success in countries such as
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
, China,
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
, the U.S., Australia, and
Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. IPM attempts to recognize the more widespread impacts of an action on an
ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
, so that natural balances are not upset. New pesticides are being developed, including biological and botanical derivatives and alternatives that are thought to reduce health and environmental risks. In addition, applicators are being encouraged to consider alternative controls and adopt methods that reduce the use of chemical pesticides. Pesticides can be created that are targeted to a specific pest's lifecycle, which can be environmentally more friendly. For example,
potato cyst nematode Potato root nematodes or potato cyst nematodes (PCN) are 1-mm long roundworms belonging to the genus ''Globodera'', which comprises around 12 species. They live on the roots of plants of the family Solanaceae, such as potatoes and tomatoes. PCN c ...
s emerge from their protective cysts in response to a chemical excreted by potatoes; they feed on the potatoes and damage the crop. A similar chemical can be applied to fields early before the potatoes are planted, causing the nematodes to emerge early and starve in the absence of potatoes.


United States

In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
, the Environmental Protection Agency (EPA) is responsible for regulating pesticides under the
Federal Insecticide, Fungicide, and Rodenticide Act The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) is a United States federal law that set up the basic U.S. system of pesticide regulation to protect applicators, consumers, and the environment. It is administered and regulated by th ...
(FIFRA) and the
Food Quality Protection Act The Food Quality Protection Act (FQPA), or H.R.1627, was passed unanimously by Congress in 1996 and was signed into law by President Bill Clinton on August 3, 1996. The FQPA standardized the way the Environmental Protection Agency (EPA) would man ...
(FQPA). Studies must be conducted to establish the conditions in which the material is safe to use and the effectiveness against the intended pest(s). The EPA regulates pesticides to ensure that these products do not pose adverse effects to humans or the environment, with an emphasis on the health and safety of children.Susan Wayland and Penelope Fenner-Crisp
"Reducing Pesticide Risks: A Half Century of Progress."
EPA Alumni Association. March 2016.
Pesticides produced before November 1984 continue to be reassessed in order to meet the current scientific and regulatory standards. All registered pesticides are reviewed every 15 years to ensure they meet the proper standards. During the registration process, a label is created. The label contains directions for proper use of the material in addition to safety restrictions. Based on acute toxicity, pesticides are assigned to a Toxicity Class. Pesticides are the most thoroughly tested chemicals after drugs in the United States; those used on food require more than 100 tests to determine a range of potential impacts. Some pesticides are considered too hazardous for sale to the general public and are designated restricted use pesticides. Only certified applicators, who have passed an exam, may purchase or supervise the application of restricted use pesticides. Records of sales and use are required to be maintained and may be audited by government agencies charged with the enforcement of pesticide regulations. These records must be made available to employees and state or territorial environmental regulatory agencies. In addition to the EPA, the
United States Department of Agriculture The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
(USDA) and the United States
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) set standards for the level of pesticide residue that is allowed on or in crops. The EPA looks at what the potential human health and environmental effects might be associated with the use of the pesticide. In addition, the U.S. EPA uses the National Research Council's four-step process for human health risk assessment: (1) Hazard Identification, (2) Dose-Response Assessment, (3) Exposure Assessment, and (4) Risk Characterization. In 2013 Kaua'i County (Hawai'i) passed Bill No. 2491 to add an article to Chapter 22 of the county's code relating to pesticides and GMOs. The bill strengthens protections of local communities in Kaua'i where many large pesticide companies test their products.


Canada


EU


Residue

Pesticide residue refers to the pesticides that may remain on or in food after they are applied to food crops. The maximum allowable levels of these residues in foods are often stipulated by regulatory bodies in many countries. Regulations such as pre-harvest intervals also often prevent harvest of crop or livestock products if recently treated in order to allow residue concentrations to decrease over time to safe levels before harvest. Exposure of the general population to these residues most commonly occurs through consumption of treated food sources, or being in close contact to areas treated with pesticides such as farms or lawns. Many of these chemical residues, especially derivatives of chlorinated pesticides, exhibit bioaccumulation which could build up to harmful levels in the body as well as in the environment. The problem is most acute in China, the largest producer of chlorinated pesticids. Persistent chemicals can be magnified through the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...
and have been detected in products ranging from meat, poultry, and fish, to vegetable oils, nuts, and various fruits and vegetables. Pesticide contamination in the environment can be monitored through
bioindicator A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...
s such as bee pollinators. There is an ongoing research focused on pesticide residues in farming system.


See also

*
Index of pesticide articles This is an index of articles relating to pesticides. 0–9 A B C D E F G H I J K L M N P Q R S T U V W, X, Y, Z See also * List of fungicides {{Horticulture and Gardening Index Pesticides Pe ...
*
Environmental hazard An environmental hazard is a substance, state or event which has the potential to threaten the surrounding natural environment or adversely affect people's health, including pollution and natural disasters such as storms and earthquakes. It can i ...
*
Pest control Pest control is the regulation or management of a species defined as a pest; any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and will range ...
*
Pesticide residue Pesticide residue refers to the pesticides that may remain on or in food after they are applied to food crops. The maximum allowable levels of these residues in foods are often stipulated by regulatory bodies in many countries. Regulations such as ...
* Pesticide standard value *
WHO Pesticide Evaluation Scheme Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...


References


Bibliography

* Davis, Frederick Rowe. "Pesticides and the perils of synecdoche in the history of science and environmental history." ''History of Science'' 57.4 (2019): 469–492. * Davis, Frederick Rowe. ''Banned: a history of pesticides and the science of toxicology'' (Yale UP, 2014). * Matthews, Graham A. ''A history of pesticides'' (CABI, 2018). *


External links


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European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...

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United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
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