An ever growing controversial topic is the use of pesticides. I choose this topic because of my interest in the environment and my lack of knowledge on this particular issue. Pesticides have been getting more and more attention and the possible impacts on the environment have been more increasingly present. This essay examines the improvement, uses, and effects of pesticides in our current world. The impacts on humans and the environment will be examined. The essay begins with an general introduction to pesticides and their history, and how they became more and more popular in our current society, looking specifically at the United States.
This paper will be primarily focused on four pesticides; DDT, Dursban, Aldrin, and Neonicotinoids – all of which have been very commonly used in the past and present throughout the world. The essay examines these pesticides and what they are used for, the impacts on the environment and humans, and what has been done to reduce these issues.
C.E. Since then, there have been many steps forward in terms of improvement of pesticides. The 1930’s was the start of the creation of synthetic pesticides, pesticides that were created by humans and not naturally occurring substances. Synthetic pesticides initial use in the US began in the 1930’s and became very common after World War II. By 1950, pesticides were found to increase farm crop yields far beyond pre-World War II levels and farmers soon depended upon synthetic pesticides to control insects in their crops.
Today, it is one of the most commonly used methods in controlling insects. However, a solution to one problem can create others. This is what will be investigated in this paper, the problems and impacts of pesticides. Due to scientific advancements and legal action, the pesticides cure toy used today are very different from the ones used during the beginning and golden age of pesticides in the 1950’s and for the most part have a much lesser environmental impact. The newest pesticides require extensive laboratory and field testing to be authorized and can take about five years to reach markets and be used widespread. A pesticide company must identify uses, test effectiveness, and provide data on chemical structure, production, formulation, fate, persistence, and environmental impacts, along with clearing the pesticide with the EPA?. The first important synthetic organic pesticide that was created was a chlorinated hydrocarbon (or organochlorine): dichlorodiphenyltrichloroethane or more commonly known, DDT. DDT was discovered in 1939 by Paul Muller, a well known Swiss chemist. In its early days, it was seen as a miracle pesticides for a number of reasons: 1. It was toxic to wide range of insect pests (“broad spectrum”) yet appeared to have low toxicity to mammals, 2. It was persistent, as it didn’t break down rapidly in the environment and didn’t have to be reapplied often, 3. It was not water soluble, so it was not washed off and destroyed by rains, and 4. It was inexpensive and easy to apply. DDT became very effective at killing pests. The following quote was said by Paul Muller after his discovery of DDT; “My fly cage was so toxic after a short period that even after very thorough cleaning of the cage, untreated flies, on touching the walls, fell to the floor. I could carry on my trials only after dismantling the cage, having it thoroughly cleaned and after that leaving it for about one month in the open air.”4 This shows just how effective and long lasting DDT was and is. DDT became used for multiple reasons other than protecting crops from insects, so widely used that cities even began using it as a means to control mosquitoes, gypsy moths, Japanese beetles, and other insects in residential areas. At the time DDT was the most popular pesticide worldwide and was used on a massive global scale, largely because of its inexpensive price for large quantities.
One of the benefits of DDT was that it was not water soluble, which was good in terms of withstanding a rain, but not good in the respect that the pesticide then built up in the rivers. The build up in the rivers caused for fish and crabs to be affected, especially juveniles, as DDT was toxic to them as well as insects. From here it was really just a progression up the food chain. The birds that ate the infected fish ingested the pesticide and it in turn affected them. This is also known as biomagnification, as birds can eat several fish a day, there is a fair chance that throughout a span of time they can accumulate quite a bit of DDT in their system from the multiple affected fish they eat. A model of this accumulation of DDT up the food chain can be seen below.
DDT concentration: increase of 10 million times DDT in fish-eating birds 25 ppm DDT in large fish 2 ppm DDT in small fish 0.5 ppm DDT in zooplankton 0.04 ppm DDT in water 0.000003 ppm DDT has been found to cause behavioral anomalies and the thinning of eggshells in populations of Bald Eagles and Peregrine Falcons, birds that very commonly ate fish in areas where they were highly affected. The thinning of the eggshell was the most detrimental environmental impact of DDT. Birds, as we know, sit on top of their eggs before they hatch in order to incubate the eggs. With the thinning of the shells, this cannot be done- the eggs would very easily break when the mother perches on top of them. With a majority of the eggs of Bald Eagles and Peregrine Falcons breaking, there were hardly any of these birds hatching- meaning that the population of these birds took a nosedive and was headed to extinction in certain parts of the world.
In the U.S. it was decided to disband all use of DDT, however in other countries, DDT is still in use”. Many of these areas still use DDT on crops that are exported to places across the globe, including the United States 10. With the use of this pesticide still present through the world, the ecosystem is still being majorily affected and changed. In many cases, we still do not know the long term effects of DDT on certain animals, environment, or if it can come back to hurt us.
Dursban Another pesticide that is still in use is Dursban. Dursban was one of the most commonly used pesticide in households, schools, hospitals, and agriculture until 200011 and is the registered trademark of Dow AgroSciences’ pesticide chlorpyrifos. Chlorpyrifos is the active ingredient in Dursban, and is what makes the pesticide harmful. Chlorpyrifos is a part of 40 widely used organophosphate pesticides, known as neurotoxic chemicals that can cause very detrimental effects. It is the third most commonly used pesticide in the home and commercially and is the
thirteenth most commonly used pesticide in agriculture, , with 11 million pounds applied annually in homes and commercially and 13 million pounds applied annually in agriculture 13.
Dursban has several common uses, one is for plant nurseries. Dursban is used on nursery grown ornamentals to treat a variety of pests and insects. It is also approved for use on soil to control white grubs when planting or before transplanting field grown nursery stock, as well as on turfgrass grown for seed and/or sod. Also a “broad spectrum” control pesticide, its manufacturer claims it controls more than 280 insect pests 14. Dursban is also used for termite treatment, called Dursban TC. Dursban TC is a termiticide concentrate used to prevent or control infestations of subterranean termites 15. Another common use is in the form of an insecticide.
Dursban as an insecticide is used as a general pest control around the perimeters of industrial buildings, along with windows, decks, fences, foundations, and garages16.
The Occupational Safety and Health Administration (OSHA) defines Dursban as a hazardous chemical?. Experimental animal studies have suggested that infants and children are more susceptible than adults to be affected from low exposure to chlorpyrifos 18. This susceptibility is due to the younger people being unable detoxify chlorpyrifos and its metabolites as quickly or at all19. Exposure to chlorpyrifos while pregnant or during childhood has been linked with lower birth weights and neurological abnormalities in epidemiological studies. Slower motor development and attention problems are potential impacts of these neurological impacts 20.
There have also been multiple studies on the effects of chlorpyrifos on animals. in many experiments upon rats, there have been lasting neurological impacts due to short-term low-dose exposures to chlorpyrifos and has affected emotional processing and cognition of the rats21. The largest neurological changes were found when the rats were still developing, during the time when sex differences in the brain is established. This has been found to even reverse the normal sex differences between males and females. the exposure to the pesticide has also affected body weight, metabolism, and the liver and chemical indicators seems as though the rat is going through pre-diabetes.22. These changes and effects could and can cause many detrimental effects that could impact the life of the rat/animal’s life severely.
In 2011, EPA estimated that, in the general U.S. population, people consume around 0.009 micrograms of chlorpyrifos per kilogram of their body weight per day directly from pesticide residue on the food they eat. children were found to consume even greater amounts, with toddlers at 0.025 micrograms of chlorpyrifos per kilogram of their body weight per day. In some rural areas, the EPA’s maximum acceptable dose of 0.3 micrograms/kg/day is reached. Before the U.S.
banned chlorpyrifos from residential use, the national NHANES study showed 91% of human urine had traces of chlorpyrifos. A 2008 study found dramatic decreases in urinary levels of chlorpyrifos metabolites when children in the general population switched from their conventional to organic diets, meaning that they switched from foods with chlorpyrifos residue to foods without this residue. This means that the Dursban used on foods is most likely what caused the chlorpyrifos accumulation.
Certain populations of people with more exposure to chlorpyrifos, such as people who apply pesticides, work on farms, or live in agricultural communities, have been found to have 5 to 10 times the levels of chlorpyrifos in their urine than any member of the general population. The California Air Resources Board (CARB) has done air monitoring studies and have cataloged chlorpyrifos present in the air of communities in California. The CARB data indicate that children living in areas of high chlorpyrifos use are often exposed to levels of the pesticide that exceed levels considered acceptable by the EPA23 and has shown that people there have higher than normal chlorpyrifos levels in their bodies, possibly causing a much higher chance to exhibit the side effects of the toxin.
On June 8, 2000, the U.S. Environmental Protection (EPA) announced an agreement it had reached with Dow AgroSciences which phased out most uses of Dursban, but not all. 24 As of 2010, Dursban is still authorized for use in agricultural applications on turf farms, indoor and outdoor nursery ornamentals, a termiticide and as an insecticide at industrial plants and other nonresidential locations25.
Aldrin Aldrin is a pesticide that enters the ecosystem and an insect’s body and rapidly converts into Dieldrin. It is a harmful and persistent environmental contaminant that the US Department of Agriculture banned the use of in 1970. However, two years later the EPA reinstated the pesticides for the removal of termites. This usage continued until the manufacturer voluntarily discontinued production in 198726. The pesticide was continued for use in East Asian countries until the late 1980’s and early 1990’s when it was banned.
Aldrin was used extensively from the 1950s to the early 1970s on crops such as corn and cotton and later used, until 1987, against termites. Aldrin is a pesticide used to control soil insects such as termites, wireworms, rice water weevil, corn rootworm, and grasshoppers. The pesticide has been commonly used to minimize wooden structures from termite damage and protect crops such as corn and potatoes.
Aldrin has been seen to cause severe health problems when ingested or inhaled in a significant quantity27. Nervous system effects- including convulsions, headaches, irritability, and nausea are witnessed in many people with extreme exposure to the pesticide. In the past, food products grown in soil treated with Aldrin or Dieldrin have probably been the primary source of dieldrin residues in fatty tissues of the general population; however, since 1970, dietary intake has shown a significant decrease28.
Aldrin is toxic to humans; the lethal dose of Aldrin for an average sized adult man has been estimated to be about 5g, equivalent to 83 mg/kg body weight29. However, this is far beyond what is averagely consumed, but even small amount can cause adverse effects. Signs and symptoms of Aldrin have been found to be headaches, dizziness, nausea, vomiting, followed by muscle twitching, myoclonic jerks, and convulsions. Occupational exposure to Aldrin was even associated with a significant increase in liver and biliary cancer. The average daily human intake of Aldrin and Dieldrin was calculated to be 19pg/person in India, and 0.55 pg/person in Vietnam. Dairy products, such as milk and butter, and animal meats are thought to be the primary sources of exposure in these areas.
The acute toxicity of Aldrin to avian species varies in the range of 6.6 mg/kg, as in the case of bobwhite quail to 520 mg/kg, for mallard ducks. Aldrin treated rice is thought to have been the cause of deaths in waterfowl, shorebirds and passerines along the Texas Gulf Coast, both by direct poisoning by ingestion of Aldrin treated rice and indirectly by consuming organisms contaminated with Aldrin. Residues of Aldrin were detected in all samples of bird casualties, eggs, scavengers, predators, fish, frogs, invertebrates, and soil.
As Aldrin is readily and rapidly converted to Dieldrin in the environment and is metabolised to Dieldrin in both animals and plants, and therefore Aldrin residues are rarely present in animals and then only in very small amounts. Residues of Aldrin have been detected in fish in Egypt, the average concentration was 8.8 ug/kg, and a maximum concentration of 54.27 ug/kg.
Neonicotinoids Neonicotinoids, or Neonics, are a relatively new pesticide, only used within the last 20 years.
Neonicotinoids are used to control a variety of pests, mostly sap-feeding insects31. Neonics are systemic pesticides, unlike the other pesticides explored before which are contact pesticides, meaning that they stay on the surface of the plants foliage and is then absorbed by the plant and transported throughout all the tissues. This includes the leaves, flowers, roots and stems, as well as pollen and nectar. Neonics however, can be sprayed as a seed coating or soil franchise at the root, or on the plant foliage. The toxin remains in the plant and active for many weeks and protects against pests for an entire season.
Neonicotinoids attacks the nervous system of insects, targeting on the receptors of the enzyme nicotinic acetylcholine. The toxin binds onto these receptors and cause overexcitation of the nerves and leads to paralysis and death of the insects33. This neural alleyway is more common in insects than mammals, and are therefore are much more abundantly toxic to insects. Neonics also do not rapidly degenerate in its environment, such as the older organophosphate pesticide do 34.
Neonics stay in the environment or so long that Imidacloprid- a type of Neonic, lasts for months and/or years and has even been found to reach groundwater. Although Neonics are so powerful, they can be applied at much lower amounts and volumes than the older pesticides, in just a few grams rather than kilos per hectare. This is due to the pesticides being active at very low amounts 35.
Originally, Neonics were thought of as a healthier and safer option for humans and animals than other pesticides. The application was seen as much more effective, as it targeted pests much more accurately and the pesticide was not needed to be applied as often as other pesticides- and in this case seen and environmentally-friendly36. However, as time has gone on it has become apparent that they pose severe and non understood threats, especially to invertebrates. These risks are due to what Neonics are made so useful to farmers and agricultural industries; the systematic actions, persistence and longevity in crops and soil, and potency and such low concentrations. On top of this, as they are so widely used and are so present with crops and their pollen and nectar, there is an ever increasing exposure, and therefore threat, to pollinators37.
Neonicotinoids are an ever growing market in the world globally, now highly sought after as they are used on more than 140 different crops38. Neonics can applied in several different ways, and can therefore be used on a large variety of crops and plants. They can be applied in soils, seeds, turfs, timbers, and even foliage for cereals, cotton, legumes, potatoes, orchard fruits, rices, and vegetables. Only five Neonics are authorized and approved to be used for agricultural purposes; clothianidin; imidacloprid; thiacloprid; and thiamethoxam. Around 90% of pesticide treatments for cereals, sugar beet, and oilseed rape are treated with Neonics. Potted plans, turfs, apples, pears, and other fruits are also widely treated with Neonics59. Neonicotinoids have become a growing concern to beekeepers and bee research in the previous years, many suspecting that the increase of Neonics are connected to the bee population decline40. Bees are especially susceptible to Neonics due to a certain genetic vulnerability. They have more enzyme nicotinic acetylcholine receptors than most other insects, and unlike most other insect pest species, bees possess few genes for detoxification-meaning that bees are unable to remove the toxin from their body.
Neonicotinoids is often present in pollen and name tar at sufficient levels to cause detrimental impacts on pollinators health, including the homing ability, foraging behavior, communication, and larvae development. Several studies have shown that exposure to the pesticide, even at low doses, has impacted immune systems of bees negatively. This has made them more likely to be affected by parasites and disease infections, which in turn has lowered the bee population. One such example of disease is the growth of Nosema fungal disease, which was reported apparent in bee populations that were exposed to low doses of Neonics-doses that had previously been considered non harmful to bees41. These effects have very likely been the cause of the bee population decrease, which in turn is causing negative effects in our entire ecosystem- as many plants have not been pollinated as they should be. Bee concerns have led to partial bans on the use of some neonicotinoids for specific crops in several European countries, including France, Germany, Italy, and Slovenia“.
Conclusion DDT, Dursban, Aldrin, and Neonicotinoids show how pesticides and environmental awareness have changed over time. Although these pesticides have allowed the world to increase food production, reduce pest and insects in rural and urban communities, and allow us to live more comfortably, they also have bad impacts upon the world as well. All of these pesticides have/had severe environmental and health impacts. These pesticides have brought species almost to extinction, had severe impacts on human health and development, and disturbed and manipulated entire ecosystems. These disturbances are causing, or could cause, problems of their own that directly impact humans and the world- such as the bee population drop is causing a decrease in the production of plants as they are not being pollinated and this has disastrous effects on the world. There have been improvements in terms of legislation and awareness. Many of these pesticides have either been banned in parts of the world or their use is severely decreased, and there have been increasing amounts of organic farming. This means that the known effects of these pesticides will decrease. However, there are still unknown effects of these pesticides and more and more are created every day. Impacts on the environment and humans due to pesticides will never go away, especially since there is no way to live life currently without them.