Environmental Pollution by Pesticides
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Over time, pesticides have generally become less persistent and more species-specific, reducing their environmental footprint. The arrival of humans in an area, to live or to conduct agriculture, necessarily has environmental impacts. These range from simple crowding out of wild plants in favor of more desirable cultivars to larger scale impacts such as reducing biodiversity by reducing food availability of native species, which can propagate across food chains. The use of agricultural chemicals such as fertilizer and des magnify those impacts.
While advances in agrochemistry have reduced those impacts, for example by the replacement of long-lived chemicals with those that reliably degrade, even in the best case they remain substantial. These effects are magnified by the use of older chemistries and poor management practices. Shortly thereafter, DDT, originally used to combat malaria , and its metabolites were shown to cause population-level effects in raptorial birds. Initial studies in industrialized countries focused on acute mortality effects mostly involving birds or fish.
The common practice of incident registration is inadequate for understanding the entirety of effects. Since , research interest has shifted from documenting incidents and quantifying chemical exposure to studies aimed at linking laboratory, mesocosm and field experiments. The proportion of effect-related publications has increased. Animal studies mostly focus on fish, insects, birds, amphibians and arachnids.
Since , the United States and the European Union have updated pesticide risk assessments, ending the use of acutely toxic organophosphate and carbamate insecticides. Newer pesticides aim at efficiency in target and minimum side effects in nontarget organisms. The phylogenetic proximity of beneficial and pest species complicates the project.
One of the major challenges is to link the results from cellular studies through many levels of increasing complexity to ecosystems. The concept borrowed from nuclear physics of a half-life has been utilized for pesticides in plants ,  and certain authors maintain that pesticide risk and impact assessment models rely on and are sensitive to information describing dissipation from plants.
Known degradation pathways are through: photolysis , chemical dissociation , sorption , bioaccumulation and plant or animal metabolism. Pesticides can contribute to air pollution. Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. As wind velocity increases so does the spray drift and exposure. Low relative humidity and high temperature result in more spray evaporating. The amount of inhalable pesticides in the outdoor environment is therefore often dependent on the season.
Pesticides that are sprayed on to fields and used to fumigate soil can give off chemicals called volatile organic compounds , which can react with other chemicals and form a pollutant called tropospheric ozone. Pesticide use accounts for about 6 percent of total tropospheric ozone levels. Pesticide impacts on aquatic systems are often studied using a hydrology transport model to study movement and fate of chemicals in rivers and streams. As early as the s quantitative analysis of pesticide runoff was conducted in order to predict amounts of pesticide that would reach surface waters.
There are four major routes through which pesticides reach the water: it may drift outside of the intended area when it is sprayed, it may percolate, or leach , through the soil, it may be carried to the water as runoff, or it may be spilled, for example accidentally or through neglect.
In the US, maximum limits of allowable concentrations for individual pesticides in drinking water are set by the Environmental Protection Agency EPA for public water systems. These standards may be issued for individual water bodies, or may apply statewide. The United Kingdom sets Environmental Quality Standards EQS , or maximum allowable concentrations of some pesticides in bodies of water above which toxicity may occur. The European Union also regulates maximum concentrations of pesticides in water. The extensive use of pesticides in agricultural production can degrade and damage the community of microorganisms living in the soil, particularly when these chemicals are overused or misused.
The full impact of pesticides on soil microorganisms is still not entirely understood; many studies have found deleterious effects of pesticides on soil microorganisms and biochemical processes, while others have found that the residue of some pesticides can be degraded and assimilated by microorganisms. In general, long-term pesticide application can disturb the biochemical processes of nutrient cycling. Many of the chemicals used in pesticides are persistent soil contaminants , whose impact may endure for decades and adversely affect soil conservation.
The use of pesticides decreases the general biodiversity in the soil. Not using the chemicals results in higher soil quality,  with the additional effect that more organic matter in the soil allows for higher water retention. Degradation and sorption are both factors which influence the persistence of pesticides in soil. Depending on the chemical nature of the pesticide, such processes control directly the transportation from soil to water, and in turn to air and our food. Breaking down organic substances, degradation, involves interactions among microorganisms in the soil.
Sorption affects bioaccumulation of pesticides which are dependent on organic matter in the soil. Weak organic acids have been shown to be weakly sorbed by soil, because of pH and mostly acidic structure. Sorbed chemicals have been shown to be less accessible to microorganisms. Aging mechanisms are poorly understood but as residence times in soil increase, pesticide residues become more resistant to degradation and extraction as they lose biological activity.
Nitrogen fixation , which is required for the growth of higher plants , is hindered by pesticides in soil. Pesticides can kill bees and are strongly implicated in pollinator decline , the loss of species that pollinate plants, including through the mechanism of Colony Collapse Disorder ,     [ unreliable source? Application of pesticides to crops that are in bloom can kill honeybees ,  which act as pollinators.
On the other side, pesticides have some direct harmful effect on plant including poor root hair development, shoot yellowing and reduced plant growth. Many kinds of animals are harmed by pesticides, leading many countries to regulate pesticide usage through Biodiversity Action Plans. Animals including humans may be poisoned by pesticide residues that remain on food, for example when wild animals enter sprayed fields or nearby areas shortly after spraying. Pesticides can eliminate some animals' essential food sources, causing the animals to relocate, change their diet or starve.
Residues can travel up the food chain ; for example, birds can be harmed when they eat insects and worms that have consumed pesticides. They protect human health by ingesting decomposing litter and serving as bioindicators of soil activity. Pesticides have had harmful effects on growth and reproduction on earthworms. Rachel Carson 's book Silent Spring dealt with damage to bird species due to pesticide bioaccumulation. There is evidence that birds are continuing to be harmed by pesticide use. In the farmland of the United Kingdom , populations of ten different bird species declined by 10 million breeding individuals between and , allegedly from loss of plant and invertebrate species on which the birds feed.
Throughout Europe , species of birds were threatened as of Reductions in bird populations have been found to be associated with times and areas in which pesticides are used. Some pesticides come in granular form. Wildlife may eat the granules, mistaking them for grains of food. A few granules of a pesticide may be enough to kill a small bird. The herbicide paraquat , when sprayed onto bird eggs , causes growth abnormalities in embryos and reduces the number of chicks that hatch successfully, but most herbicides do not directly cause much harm to birds. Herbicides may endanger bird populations by reducing their habitat.
Fish and other aquatic biota may be harmed by pesticide-contaminated water. Application of herbicides to bodies of water can cause fish kills when the dead plants decay and consume the water's oxygen, suffocating the fish. Herbicides such as copper sulfite that are applied to water to kill plants are toxic to fish and other water animals at concentrations similar to those used to kill the plants.
Repeated exposure to sublethal doses of some pesticides can cause physiological and behavioral changes that reduce fish populations, such as abandonment of nests and broods, decreased immunity to disease and decreased predator avoidance. Application of herbicides to bodies of water can kill plants on which fish depend for their habitat. Pesticides can accumulate in bodies of water to levels that kill off zooplankton , the main source of food for young fish.
The faster a given pesticide breaks down in the environment, the less threat it poses to aquatic life. Insecticides are typically more toxic to aquatic life than herbicides and fungicides. In the past several decades, amphibian populations have declined across the world, for unexplained reasons which are thought to be varied but of which pesticides may be a part. Pesticide mixtures appear to have a cumulative toxic effect on frogs. Tadpoles from ponds containing multiple pesticides take longer to metamorphose and are smaller when they do, decreasing their ability to catch prey and avoid predators.
The herbicide atrazine can turn male frogs into hermaphrodites , decreasing their ability to reproduce. Crocodiles , many turtle species and some lizards lack sex-distinct chromosomes until after fertilization during organogenesis , depending on temperature. Embryonic exposure in turtles to various PCBs causes a sex reversal. Across the United States and Canada disorders such as decreased hatching success, feminization, skin lesions, and other developmental abnormalities have been reported.
The effects of pesticides on human health depend on the toxicity of the chemical and the length and magnitude of exposure. Every human contains pesticides in their fat cells. Children are more susceptible and sensitive to pesticides,  because they are still developing and have a weaker immune system than adults. Children may be more exposed due to their closer proximity to the ground and tendency to put unfamiliar objects in their mouth. Hand to mouth contact depends on the child's age, much like lead exposure. Children under the age of six months are more apt to experience exposure from breast milk and inhalation of small particles.
Pesticides tracked into the home from family members increase the risk of exposure. Exposure effects can range from mild skin irritation to birth defects , tumors, genetic changes, blood and nerve disorders, endocrine disruption , coma or death. Recent increases in childhood cancers in throughout North America, such as leukemia , may be a result of somatic cell mutations. Both chronic and acute alterations have been observed in exposees. Fetal DDT exposure reduces male penis size in animals and can produce undescended testicles.
Pesticide can affect fetuses in early stages of development, in utero and even if a parent was exposed before conception. Reproductive disruption has the potential to occur by chemical reactivity and through structural changes. Persistent organic pollutants POPs are compounds that resist degradation and thus remain in the environment for years. Some pesticides, including aldrin , chlordane , DDT , dieldrin , endrin , heptachlor , hexachlorobenzene , mirex and toxaphene , are considered POPs.
Some POPs have the ability to volatilize and travel great distances through the atmosphere to become deposited in remote regions. Such chemicals may have the ability to bioaccumulate and biomagnify and can biomagnify i. Pests may evolve to become resistant to pesticides. Many pests will initially be very susceptible to pesticides, but following mutations in their genetic makeup become resistant and survive to reproduce. Resistance is commonly managed through pesticide rotation, which involves alternating among pesticide classes with different modes of action to delay the onset of or mitigate existing pest resistance.
Non-target organisms can also be impacted by pesticides. In some cases, a pest insect that is controlled by a beneficial predator or parasite can flourish should an insecticide application kill both pest and beneficial populations. A study comparing biological pest control and pyrethroid insecticide for diamondback moths , a major cabbage family insect pest, showed that the pest population rebounded due to loss of insect predators , whereas the biocontrol did not show the same effect. Loss of predator species can also lead to a related phenomenon called secondary pest outbreaks, an increase in problems from species that were not originally a problem due to loss of their predators or parasites.
Many alternatives are available to reduce the effects pesticides have on the environment. Alternatives include manual removal, applying heat, covering weeds with plastic, placing traps and lures, removing pest breeding sites, maintaining healthy soils that breed healthy, more resistant plants, cropping native species that are naturally more resistant to native pests and supporting biocontrol agents such as birds and other pest predators. Biological controls such as resistant plant varieties and the use of pheromones , have been successful and at times permanently resolve a pest problem.
IPM causes less harm to humans and the environment. The focus is broader than on a specific pest, considering a range of pest control alternatives. Strains can be genetically modified GM to increase their resistance to pests. From Wikipedia, the free encyclopedia. See also: Pesticide drift. United Kingdom. Of the 15 persons who had complained of symptoms, all but 3 recovered before arriving at the hospital, and these 3 recovered within a few hours without any treatment.
Quinby and Clappison72 reported a case of unusual persistence of parathion. A 2-year-old boy had eaten mud on which a parathion concentrate had accidentally leaked 6 months previously. The soil had been leached by water and snow for 6 months and still remained sufficiently toxic when ingested to cause an acute poisoning in the youngster.
West and Milby reported four deaths in California due to the use of lindane in the home. Other incidents have also been reported. Sufficient evidence exists that the general world population now carries a body burden of DDT, and the level in any given individual is dependent on his history of exposure.
This value of Regarding chronic effects and toxicity of stored dieldrin, Heath and Vandeker45 concluded that symptoms should not appear later than 2 months after the last expo- sure unless fat depots are greatly decreased by illness or starvation, and there should not be any special sensitivity to a second dose after 6 months.
Campbell et aA. They concluded that food sources constitute the chief source of DDT intake, and that air only represents 0. The number of deaths for these 2 years and the associated pesticides are shown in Table 5, Appendix A. Of the cases, 57 51 percent were in children under 10 years of age; at least 64 58 percent were caused by compounds in use before the introduction of DDT; not more than 17 15 percent were occupational; and several cases were associated with alcoholic intoxication, mental deficiency, improper storage of the pesticide, or some other special circumstance.
Insecticides caused 62 of the deaths; herbicides, 15; rodenticides, 25; fungicides, 2; and 7 were unspecified. The distribution of deaths according to age and route of exposure and whether occupa- tional is presented in Table 6, Appendix A. Five deaths of the total were attributed to respiratory exposure. Accidental deaths from pesticides and other agricul- tural chemicals in California from to are listed in Table 7 in Appendix A.
Usually, such animal exposures are carefully con- trolled and no ill effects are noted. These acute poisoning accidents usually were due to carelessness or misuse of the pesticides and involved the more toxic organophosphates in addition to endrin and dieldrin. As in humans, chronic effects have been difficult to identify in domestic and wild mammals. Except for methoxychlor, all are 18 stored in the body fat at various levels. Again as with humans, the significance of this storage on health is not completely understood.
The presence of DDT and other stored pesticide residues in the secreted milk of dairy animals has been of concern since it relates to humans and it also provides a method for study of these residues. Only insignificant amounts of Toxaphene are present, and practically no methoxychlor. After ingestion of as little as 7 to 8 ppm of DDT on hay a normal residue follow- ing spraying , approximately 3 ppm will be secreted in cow's milk, and butter made from such milk will contain about 65 ppm.
This fluctuation was correlated with ingestion of residue in the feed at the higher dosage levels but not at the lower levels. They also studied the relative importance of respiratory intratracheal exposure of the cows as compared with other means of exposure to DDT. Their results Table 8, Appendix A showed that intra- tracheal exposure resulted in slightly less total excretion of DDT and its metabolites in milk than either of the two alimentary modes of exposure.
Fowl, fish, and many lower forms of wildlife have been extremely susceptible to low dosages of DDT and related insecticides. DDT residues in the bodies of such animals have been reported in all parts of the world, including p O penguins in the Antarctic. Birds are particularly affected by such residues because they interfer with calcium deposition in eggs. Thin-shelled eggs are laid thus causing a loss in reproduction.
West and Dustman have reviewed many of these occurrences of the effects on wildlife. Cattle have been poisoned by drifting dust of 1 per- cent TEPP. Three incidences occurring in Washington in August were observed and documented. In one instance, 15 cattle showed symptons of staggering, gasping for air, drooling, and some degree of cyanosis; two young cows died within the second hour after onset of the symptoms.
Two geese, a cat, and chickens in the same dust cloud were not harmed. In another incident, a heifer in an open barn began coughing and developed symptoms of respiratory stress within 30 minutes of initial exposure. It was given one- fourth grain of atropine and was normal by the next morning. In the third incident, 17 head of cattle became severely ill after exposure to TEPP dust, with symptoms of diarrhea, excessive urination, wobbly gait, and loss of appetite. All recovered without special treatment.
The phenoxyacetic acid herbicide derivatives 2,4-D and 2,4,5-T are comparatively harmless to most animals. All of the alleged cases of herbicidal poisoning of livestock and wildlife have been diagnosed as due to things other than herbicides. Inhalation of these herbicide dusts and sprays is relatively harmless, and percutaneous absorption is negligible.
Even when administered to cows in large doses by ingestion, 2,4-D has not been found in the secreted milk. Exposure of poultry to abnormally high residues of these herbicides led to reduced egg production but did not affect fertility or hatchability. However, the newer fungicides such as dodine, zineb, and 1 o maneb appear to present little toxic hazard. Compared with the total number of such studies, relatively few have utilized air as the means of exposing animals to the pesticide.
Therefore, the following discussion will be concerned with some of the important areas of study, regard- less of the means of exposure, in which the findings are relevant to air pollution aspects. The acute oral and dermal LDs0 values of the most common insecticides are listed in Table 9, Appendix A.
Department of Health, Education, and Welfare. Data on long-term feeding of low dosages of pesticides to experimental animals have been tabulated by Mitchell Table 10, Appendix A. He has summarized some of the data c o collected by Lehman relating to the dietary levels of pesticides that produced minimal or no effects after continuous feeding for 90 days to 2 years.
Approximately the same dietary levels of chlorinated hydrocarbon insecti- cides and the organophosphorous insecticides were required to produce minimal or no effects. These levels are significantly lower than levels observed with the fungicides and herbicides which both required similar dietary levels. Rats showing severe tremors had brain concentrations ranging from to ppm; those with convulsions, to ppm; and those with convulsions and death had DDT concentrations ranging from to ppm in the brain tissue.
The animals that recovered from exposure to DDT to ppm showed decreasing concentrations of DDT in the brain within. The concentra- tions associated with death after one large dose were about the same as those following many smaller doses. The investigators' studies showed that in addition to the brain, all parts of the nervous system were affected, but indica- tions were that the effects on the brain were the most important. The data indicated that, regardless of how the DDT was administered, the probability that death would occur was increased if concentrations of DDT in the brain exceeded ppm in otherwise healthy rats or exceeded ppm in debilitated rats.
In addition, rats that survived one dose of dieldrin remained much more sensitive than normal rats given a second dose within 3 weeks. That is, two equal doses given within 3 weeks of each other were more toxic than the same two given as a single dose. Heath and Vandeker explained these results as due to the low solubility of dieldrin in water, its solu- bility in fat, and its mobilization in the body when fat is utilized. They concluded that the toxic effects of dieldrin were related to dieldrin mobilization, and that there was no need to postulate that dieldrin produced a long-lasting effect in the central nervous system.
Death occurred within 1 to 25 hours from respiratory failure, usually following convulsions. Ninety rats whose growth had been stunted by feeding of a low protein casein diet from the time of weaning were twice as susceptible to the toxic effects of lindane as rats fed a normal diet. However, a daily dietary intake of one-nineteenth of an acute LD50 of dieldrin produced convulsions and death in some rats within a month.
A possible explanation for these observations is that parathion, even at a high subfatal dosage, is excreted from the body in a few days, wheras dieldrin is stored and eliminated only very slowly, Laboratory studies have shown that rats are mox-e susceptible to parathion than to endrin. However, meadow mice Microtus apparently are more sensitive to endrin and are relatively insensitive to parathion. It was observed that meadow mice populations practically disappeared when their habitat and food supply were sprayed once with endrin, but they were not noticeably affected when parathion was applied even several times during the year.
Evidence has been reported that some pesticides can undergo photochemical isomerization to yield products of different toxicity than the parent material. The amount of dieldrin present in the tissues of rats fed 1 and 10 ppm of dieldrin was reduced by the addition of 5 ppm DDT to the feed. The addition of 50 ppm DDT to the feed caused a fold reduction in dieldrin storage in rats fed 1 ppm dieldrin and a 6-fold reduction in rats fed ppm dieldrin. In a following 91 study, female rats were fed a diet for 10 weeks containing 0. Storage of DDT when fed at the 50 ppm level was increased by the high dieldrin treatment.
Methoxychlor storage was not affected by the other treatments; however, methoxychlor caused a small but significant reduction in the dieldrin storage. The DDT effect was postulated to result from enhanced dieldrin metabolism by liver microsomial enzymes. The dogs were treated as follows: Group 1: 0. The possibility of two or more pesticides having an additive toxicity effect potentiation has been under investigation. No potentiation with other organophosphorous insecticides in dogs. Carbaryl: no potentiation with other organophos- phorous insecticides in rats. Co-Ral: potentiation with piperonyl butoxide and malathion.
Guthion: no potentiation has been observed. Delvon: some degree of potentiation with malathion in rats. Ethion: approximately a 3-fold increase with malathion in rats, and slight increase in dogs. Ronnel: mild potentiation with malathion in rats. One of the long-term effects of exposure to certain chemicals is the production of tumors, some of which are cancerous. The following pesticides have been listed by West1 as suspected carcinogens: Aminotriazole, aramite, arsenic dithiocarbomates, DDT, aldrin, heptachor, dieldrin, endrin, 8-hydroxyquinoline, ethylene oxide, propylene oxide, and piperonyl compounds.
However, the carcinogenic effects of pesticides have been observed in animals at relatively high concentrations and no carcinogenic effects have been observed at the concentrations found in ambient air. Therefore, these materials generally have no adverse effect- on plant growth. Herbicides, however, have been developed specifically to prevent the growth of plants. They can be classed into two categories, selective affecting only certain types of plants and nonselective affecting all types of plants.
However, there are only quantitative differences for many herbicides in the two categories; many selective herbicides, when used in higher dosages, become nonselective. The problems associated with the drift in the air of herbicides are discussed in Sections 3. Also, translocation of insecticides into the plant from the soil and the plant surface has been observed and studied.
Birdsall et al. Flavor changes, although not objectionable, were found in strawberries treated with kelthane, endrin, diazinon, heptachlor, chlordane, or aldrin; and in raspberries treated with heptachlor, chlordane, or aldrin. Mahoney has reviewed this subject and presents many such examples of flavor changes. Lindane and BHC have imparted undesirable flavors to many foods: potatoes, sweet corn, carrots, green beans, turnips, onions, and squash.
Problems have also arisen as a result of crop rotation; instances have occurred in which processed sweet corn had to be destroyed after being grown in fields which contained alfalfa the year before and had been treated with 0. Lichtenstein54 observed translocation of DDT, lindane, and aldrin into crops such as carrots, beets, cucumbers, potatoes, radishes, and rutabage. It was concluded that under the normal low levels of treatment, none or only traces of insecticides in these crops would have been found.
Additional data on this topic can be found in the review by Lichtenstein. Foreign on standards for some pesticides have been listed by Stern and are listed in Table 13, Appendix A. DDT production increased to million pounds in 15 years. BHC production reached about 77 million pounds in , which was about equal to the production of DDT that year.
Other organic pesticides, such as the herbicide 2,4-D, have increased in production continuously since they were first used as pesticides Table 14, Appendix A. As a result of the increased production of organic pesticides, the production of arsenicals and other inorganic pesticides declined.
Lead and calcium arsenate production totaled approximately million pounds in , whereas only about 8 million pounds are currently used Table 14, Appendix A. In addition, there has been a considerable decline in the use of botan- ically derived materials, such as rotenone and pyrethrum. The total production and sales of synthetic organic pesticides in the United States for the years to are shown in Table 17, Appendix A.
The preliminary estimate for places production at slightly in excess of 1 billion pounds and the manufacturers' value at approximately million dollars. The annual growth rate in total sales value for the to period has averaged about 15 percent. This growth has been due in part to increased costs of production, but primarily to increased production volume and usage. The manufacture, formulation, and packaging of pesticides present possible air pollution hazards.
The pesticides are generally manufactured in closed systems of a continuous-process nature. The process systems are normally maintained at a slightly negative pressure to avoid leakage. Tabor sampled the air in a community Fort Valley, Ga. He noted that DDT concentrations in ambient air ranged up to 0. He concluded that most of the DDT found in the air during September came from the formulating plant.
Production plant sites for pesticides are presented in Table 18, Appendix A. Table 19, Appendix A, presents the latest available survey for the overall farm usage of pesticides in the United States. Agricultural usage accounted for about Of the total used, the fungicides, insecticides, and herbicides constituted approximately 90 percent of all pesticides. The comparison of the farm use of selected pesticide chemicals with the production for is shown in Table 20, Appendix A.
Approximately 42 percent of the total production was used by farmers; the remainder was used for export and domestic nonagricultural purposes. Data showing the acreages in various land-use categories annually treated with insecticides are shown in Table 21, Appendix A. Cropland and cropland pasture constituted more than 75 percent of the treated area, with cereal crops accounting for nearly 50 percent of the treated area in this category The quantities of selected types of insecticide, herbicide, and fungicide ingredients used on crops in by geographical regions are presented in Tables 22, 23, and 24, respectively, in Appendix A.
Crop insecticides were most heavily used in the Southern regions of the country. The three leading areas were the Southeast 35 million pounds , the Delta 27 million pounds , and the Southern Plains 20 million pounds. Herbicide use was heaviest in the corn belt, which used approximately 25 percent of the total applied to crops. The two regions which used the greatest amount of fungicides were the Southeast with 44 percent of the total, and the Pacific region with 26 percent of the total usage. Since much of this application is by spraying or dusting, some part of the quantity dispensed can remain in the atmosphere and be diluted and dispersed.
Pesticidal sprays and dusts usually drift over relatively short distances. However, drift to streams and ponds or to land areas not intended to be treated has been common, particularly when application is by airplane. Moreover, drift from application with ground equipment also has occurred. The reported presence of low levels of pesticides in fish and wildlife has been suggested as evidence of the persistance and the distribution of pesti-.
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Many of the serious drift problems have occurred when chlorinated hydrocarbon pesticides were applied under proper conditions to fields or orchards adjacent to fields containing cattle forage but nevertheless drifted into the forage. The physical state of the pesticide spray or dust , particle size, extent of the area being treated, as well as volatility of the herbicide should be considered when phenoxyherbicides are used. Gen- erally, application by airplane tends to result in more drift than by ground equipment because, regardless of other factors, more control is possible with ground than with aerial equipment.
Dusts have a greater tendency to drift than do sprays, to the extent that the Federal Government has banned the use of 2,4-D dusts. Akesson and Yates reported that a pesticide dust composed of particles 10 p. The microclima- tology is important in determining the movement and disper- sion of the drift. Although drift of pesticides can be minimized by careful application in agricultural use, it was their belief that a certain amount of drift was unavoidable.
The potential of nonoccupational human acute poison- ing resulting from the drift of pesticides should always be considered even though very few incidents of such poisonings have been reported.
Quinby and Doornink73 in their discus- sion of these occurrences, emphasized that the same dusting procedures had been used for the previous 16 years in that area of the country; an infrequent combination of several factors had occurred, trapping the dust cloud in the air for periods long enough for people in the area of drift to breathe sufficient TEPP to cause shortness of breath. These factors were 1 thermal inversion and a static air condition for longer than an hour over a large area 2 topography of the land, causing interference with even a slow movement of the dust cloud and 3 tall growing crops with dense foliage, also interfering with air movement.
Pesticides are released into the atmosphere during application in public areas, buildings, and homes. Pesticides may be inhaled in dusts from treated soils, from house dust contaminated by applica- tions for household pests, or from moth-proofed rugs, blankets, and clothes. The increased availability of pesticides for the home has led to increased usage each year. In , the annual sales of aerosol pesticide canisters was reported to be one per household. Although several fatalities resulting from inhalation of volatile pesticides in the home have been reported, nothing is known of the incidence of mild illnesses caused by home use of pesticides.
They found no evidence that volatilization occurred with DDT, Sevin, and parathion. They concluded that volatilization of insecticidal residues from soil was a major factor in their disappearance. In addition, assuming a tendency to equili- brate, treated soils would lose pesticides and untreated soils would gain them. Additional studies revealed that cover crops such as alfalfa increased the persistence of volatile pesticides in the soil.
In insecticide-treated soils, two or three times more insecticidal residues were recovered from alfalfa- covered plots than from fallow ones.
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Bowman et al. Spencer and Cliath found in their studies that the vapor density associated with solid-phase dieldrin HEOD and dieldrin soil mixtures as measured by the gas saturation technique was 3 to 12 times greater than predicted from published vapor pressure values. The vapor density of HEOD in soil at ppm was the same as that of HEOD alone, but at 10 ppm the vapor density in soil was reduced approximately 80 percent. The data indicated to Spencer and Cliath that the codistil- lation phenomenon does not result from an increased vapor density in the presence of evaporating water, and that loss of water is not required to attain maximum vapor density of HEOD, either in soil or above HEOD-water mixtures.
Wheatley and Hardman observed increases in dieldrin residue levels in a plot of soil untreated with insecticide. They considered the possibility that rainfall could wash out quantities of dieldrin when present in the ambient air and account for the increase. The findings are presented in Table 25, Appendix A. Although the inves- tigators detected small quantities of gamma-BHC, dieldrin, and p,p'-DDT in the rainwater, their conclusion was that these concentrations were insufficient to account for more than a small proportion of the pesticides present in the soil.
However, the presence of organochlorine insecticides in the atmosphere and in rain would aid their dispersion in the environment and might partially explain the occurrence of residues in unexpected places. The presence of organochlorine pesticide residues 2 in rainwater was also observed by Abbott et al.
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They collected monthly rainwater samples on roofs of two buildings approximately 1. The quanti- ties of organochlorine insecticides detected, based on detection limits of 5 parts per million-million for BHC and 10 parts per million-million for the other organochlorine insecticides, are presented in Table 26, Appendix A.
These results suggested to them that the atmosphere carries, either as vapor or by occlusion on dust particles, small amounts of the organochlorine pesticides in common use in Great Britain, and that they are scrubbed out by rain and snow. The movement of the dust-bear ing air mass had been followed by meteorologists as it spread east and northeastward and passed over Cincinnati.
A sample of the dust collected in Cincinnati was shown to contain seven identifiable pesticides: DDT and chlordane as the major pesticide components; lesser amounts of DDE and ronnel; and minor amounts of heptachlor epoxide, 2,4,5-T, and dieldrin Table 27, Appendix A. Storage and handling of pesticides presents a possible air pollution problem. Pesticides are usually stored in bags; glass, plastic, or metal bottles; or cans or drums. Contamination of the air may occur during handling, storage, or transit from breakage, leakage, or spillage. Batchelor and Walker11 in obtained 94 air samples from various locations in an orchard where aerial parathion application operations were being carried on.
The highest concentrations were observed in the area of loading and mixing and ranged from a trace to 5, J. The dermal exposure under these conditions appeared to Batchelor and Walker to be considerably greater than the exposure by inhalation. Middleton J has cited early reports of as much as ! The rate of application was 0. Indications were that the air sampling measured only 12 percent of the insecticide, because the drop size was too large to be trapped by the sampler; however, the 12 percent probably represented the respiratory exposure.
It was calculated that a man working in the open received a total respiratory exposure of The ambient air concentra- tions obtained during spraying are shown in Table 28, Appendix A. Tabor, in a series of studies in and , found pesticides in the air of communities adjacent to agricultural areas where large quantities of pesticides are used on crops. The sampling was performed in the center of the community, and areas of spray application were generally at least a mile from the sampler. The samples were collected on glass fiber filters, and only particulate pesticide quantities could be determined.
His results are given in Table 29, Appendix A. He also sampled the air of four urban communities during insect control programs. Samp- ling was done within one-half mile of the fogging applica- tion. The results obtained are given in Table 29, Appendix A, A calculated possible respiratory intake of DDT was made for five of the communities.
Hindin et al. They observed that no detectable levels of DDT or ethion were present in the air prior to application but were detected in samplings for as long as two weeks Table 30, Appendix A after application. Bamesberger and Adams8 collected air samples near Pulman and Kennewick Highlands, Wash, between April 16 and August 6, , and examined them for aerosol and gaseous 2,4-D and 2,4,5-T herbicides.
They collected hour samples of air impinged on air impaction discs rotating through a n-decane collection fluid to retain the droplets of impacted aerosols. The gaseous fraction was collected in a modified midget impinger containing a two-phase n-decane and 3 percent aqueous sodium bicarbonate solution. Their data are presented in Table 31, Appendix A.
These results are given in Table 32, Appendix A. Abbott et al. Although the quantities of organochlorine insecticide residues detected were small Table 33, Appendix A , their presence in air might be important. The most recent and extensive program of monitoring the ambient air for concentrations of pesticides has been performed by the Midwest Research Institute MRI in to for the United States Food and Drug Administration. Air samples were obtained at each locality for 2 weeks out of each 4 weeks during the sampling period for a total of 6 months of sampling.
The sampling units were designed to trap both particulate and gaseous pesticides in the air. Heptachlor epoxide, chlordane, DDD, and 2,4-D esters were not found in any samples; aldrin and 2,4-D were found in one sample each. Organophosphate pesticides were found only in samples from Dothan, Orlando, and Stoneville, methyl parathion at each of the three areas, parathion and malathion only at Orlando, and DEF a cotton defoliant only at Stoneville.
Pesticide levels ranged from the lower limit of detection of 0. The pesticide levels that were found varied according to locality and season and generally were lower in urban areas than in agricultural areas. The highest levels were found in the rural areas of the South: Dothan, Orlando, Stoneville; relatively low levels were found in the other rural areas near Buffalo and Iowa City. The appreciable levels found in the urban area of Salt Lake City could be attributed to the mosquito control activity there; the levels were quite low in the other urban areas of Baltimore, Fresno, and Riverside.
Higher levels had been anticipated in Fresno and Riverside, since both cities are surrounded by major agricultural activities, but the sampling may have been conducted too far from the spraying operations for higher concentrations of pesticides to be present in the air. It appears that the contamination arising from the produc- tion processes can be controlled. Although incidences of occupational poisonings have been reported see Section 2. Pre- cautions similar to those used in general chemical industries are taken to prevent the dusts and fumes from leaving the production plant into the outside environment.
Bag packers, barrel fillers, blenders, mixing tanks, and grinding opera- tions are generally completely enclosed or hooded and the air is vented through baghouses or cyclone separators. Similar control procedures are used when liquids are in- volved; liquid scrubbers are used however, instead of baghouses. The control of chemical drift as a source of pesticide air contamination has been studied extensively- Akesson and Yates6 have reviewed the literature, including their own research on drift control.
Although the emphasis has been placed on control of aerial applica- tions, applications made with ground equipment can also result in drift. However, greater operator control is possible with a ground unit, since it generally has a lower discharge rate than aerial equipment.
The physical state of the pesticide is quite important in drift. The drift potential from pesticide dust is very high because of particle size. Dust materials are generally screened to incorporate only particles ranging from 1 to 25 jj. Spray droplets of 50 u in size show less drift than dusts of smaller particle size see Section 3. Therefore, the use of dusts has been decreasing in recent years, and the Federal Government has banned the use of 2,4-D dust. MacCollom,59 in a study of a Vermont apple orchard where Tedion dusting for apple insect control had been the standard practice for the previous 10 years, found that drift could be a problem even under ideal weather conditions.
He noted that under conditions of a windspeed of 1. In contrast to conventional oil-in-water emulsions, preparations containing a high water content are quite viscous. When using the invert emulsions, sprays consisting of large droplets can be delivered aerially, minimizing both drift and evaporation. Trials indicated that smaller quantities of pesticide could be used in the invert emulsion with equivalent results in terms of insect kill or herbicidal efficiency.
At the same time, the accuracy of delivery was improved so that the invert emul- sions could be applied under more adverse meteorological conditions than conventional sprays.
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Various spray nozzles have been designed and used with varied pesticide formulations having different visco- sity, density, and surface tension in attempts to control drift during application. Additional factors such as the angle of the nozzle with airstream or the use of screens or discs at the nozzle also contribute to the characteristic of the spray.
These factors are discussed in detail by Akesson and Yates. Meteorological conditions are extremely important parameters that are considered in the application of pesti- cides and the control of potential drifts. Wind direction and velocity, humidity and temperature at ground and higher levels, and the amount of sunshine or rain are all inter- related factors that are considered. Weather Bureau provides this specialized data as part of their service. Dusting and spraying advisories are sent out on a teletypewriter circuit 24 hours a day emphasizing local weather conditions for aerial and ground applications for various agricultural chemicals.
In addition, these advisories include information relating certain insect and other pest activities with weather conditions, so that pesticides can be applied at the proper time to produce maximum pest control. However, the control of this is complicated by the fact that the extent to which volatilization occurs is not known. Some control over volatilization from soil can be effected by the use of cover crops.
It has been observed that two to three times more insecticidal residues were recovered from alfalfa-covered plots than from fallow ones. The President's Science Advisory Committee reported, that modern agricultural efficiency is maintained only through the use of pesticides. It has been estimated that without the use of pesticides, 50 percent of the agricultural and forestry crops of California would be destroyed, and that the present loss in spite of pesticides is 21 percent.
In addition, pesticides have contributed to the eradication or reduction of a number of human diseases such as malaria, typhus, and yellow fever in less developed countries of the world. Malaria at one time had a severe economic impact on the Southern States in the United States, but today it is almost nonexistent. These benefits have been not only in increased yields of production, but also in increased quality of the product.
In many cases, the improvement in quality has been such that a high percentage of the crop would not have been otherwise marketable.
In California, for example, in crops not treated with insecticides the percent of wormy fruit in was 21 to 23 percent, but it was only 0. Some examples of increased crop yields from use of insecticides, herbicides, and fungi- cides are presented in Tables 39, 40, and 41 in Appendix A.
Although the value may vary for different crops and regions of the country, it has been estimated that nationally about five dollars are saved for every dollar invested in chemical pesticide usage. Data on the pro- duction, sales, and usage of pesticides are presented in Section 3. No tabulated data on costs of damage due to air pollution from pesticides have been found in the literature. Akesson and Yates have reported that many lawsuits have arisen from such episodes and that liability insurance has been made available to operators of pesticide equipment, The costs of pesticide damage to wildlife resulting from air pollution is impossible to estimate.
The direct effects of such pollution on wildlife, if compared with those on livestock, are probably small. However, the indirect effects on the entire ecosystem resulting from the presence of pesticides in the air might be greater. However, at the present time, insufficient information exists regarding the translocation of pesticides in the ecosystem to make any valid cost estimates or conclusions.
The economic costs of pesticide contamination of the air with respect to human health have not been estimated. While there have been reported episodes of death or illnesses resulting from respiratory exposure to pesticides, it is not known how many unreported illnesses may occur. Furthermore, outside of those costs estimated for agricultural damage, there appears to be no cost figures available for controlling air pollution by pesticides from manufacturing or formulating plants.
METHODS OF ANALYSIS The analytical procedures for the determination of pesticides in the environment generally involve four steps: 1 a sampling method that collects a sufficient quantity of the material to permit analysis, 2 an extraction procedure to remove the specific pesticide s from the bulk of nonpesti- cide environmental material, 3 separation or "cleanup" to remove nonpesticidal interfering materials carried along during the extraction, and 4 detection and identification. Table 42, Appendix A, presents the analytical sensitivity which has been acquired over the years as understanding of the pesticide residue subject has increased.
In another study, air samples were collected at rooftop level in Pittsburgh with a two-stage sampling system to separate air- borne dust into two fractions. The large particles were collected by sedimentation on 71 horizontal trays, and particles which penetrated through this section of the sampler were collected on an MSA B glass-fiber filter. Each sample of particulates was obtained by continuous sampling at an average flow rate of 1. An air sampling system for the differential collection of aerosol and gaseous fractions of airborne herbicides has o been reported.
It consists of a rotating disk impactor for collecting aerosol droplets down to approximately 3 a in diameter, followed by a midget impinger to collect the gaseous fraction. The impactor was specially designed and constructed of glass, Teflon, and stainless steel to prevent contamination of the collection fluid with substances that interfere with electron capture gas chromatography. Incoming air impinges on the impaction disk that rotates slowly through a fluid well containing n-decane.
The impacted droplets wash off into the collection fluid. There are other sampling techniques used to measure operators' hazards in the field. The level of exposure may be determined by the amount of toxicant trapped on the filter of a respirator worn by the operator. Samples are also collected in a special respirator which is modified to simulate nasal breathing characteristics.
Contact samples are collected on pads attached at suitable points on the operators' clothing. Additional samples may be taken by means of suction-operated equipment placed in the breathing zones. The mass to size ratios of airborne particles are evaluated by sampling the air in the breathing zones through cascade impactors and also by collecting the fallout on slides set at different heights in C Q the working area. Air samples were collected at tractor operators' breathing zones using all-glass fritted absorbers and electric or hand-operated suction pumps.
Exposures were also determined 49 by attaching filter pads to double-unit respirators. The extraction and "cleanup" procedure for the Midwest Research Institute sampling train is as follows: The filter- cloth is washed with methanol.
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The alcoholic mixture is poured over an alumina adsorbent which has previously been transferred to a chromatography tube. The treated alumina column is extracted with hexane. The impinger solution 2- methyl-2,4-pentanediol is diluted with water and this solution is extracted with hexarie. The combined hexane ex- tracts are concentrated by evaporation. The treated hexane solution is passed through a Florisil column and the pesti- cides eluted from the column by first adding 0. The two solutions are concentrated before final analysis by gas chromatography. The residues of extracts were analyzed by gas chromatography without further treatment.
Three types of chromatography can be used for the quantitative determination, of pesticide residues:, 1 gas chromatography, 2 thin-layer chromatography, and 3 paper chromatography. The gas chromatographic technique has been used to separate complex pesticide mixtures in a single operation.
A highly sensitive detector for chlorinated pesticides is the electron-capture detector. It is capable of measuring some chlorinated pesticides in concentrations as low as the nanogram range 10 g. Another detector widely used with gas chromatography of chlorinated hydrocarbons is the microcoulometric detector. This detector operates on the following principles: 1 As each chlorinated pesticide emerges from the chromatographic column, it passes through a combustion tube where the pesticide is burned with oxygen to yield hydrogen chloride, water, and carbon dioxide.
The detector can measure as little as 10 g of chlorine or sulfur. The Midwest Research Institute64 method of analysis uses gas chromatography- The chlorinated pesticides were determined by using two different columns with an electron-capture detec- tor. The organophosphate pesticides were determined by using two different columns with a flame photometric detector.
A summary list of major analytical instrumentation or techniques is presented in Table 43, Appendix A. Westlake and Gunther have reviewed detection systems used in pesticide residue evaluations. Table 44 Appendix A lists the available systems and the minimum detectability of each. Detectability as used in the Table refers to Suthle Sutherland's definition; the detectable level is the concentra- tion of pesticide above which a given sample of material can be said, with a high degree of assurance, to contain the chemical analyzed.
Westlake and Gunther in their review have discussed each of the available methods, including illustra- tions of the devices and literature references to their use. By comparison with a certain class of substances, the pesticide can be identified and determined. This method does not give precise identifica- tion and cannot be applied without purification of the extracted material. Organophosphorous Pesticide Residues.
In applying the Chemical Group Analysis technique to these residues, phos- phorus is usually determined quantitatively, not the pesticide compound. The essence of the method is the extraction and "cleanup" of the residue to insure the absence of natural phosphorous compounds. The phosphorous in the subdivided ex- tract is eventually converted to phosphoric acid by wet oxida- tion.
The subsequent addition of ammonium molybdate and reduction with stannous chloride produces a heteropoly blue color which is compared against standards produced from solutions of known phosphorous content. This method has only limited selectivity and is sensitive down to 5 [ag of any one pesticide, i.
A simple screening method for the rapid estimation of organophosphorous pesticides using the above chemical-end-method of analysis has recently been introduced. Colorimetric and esterase-inhibition methods of estimating total phosphorous have been used to develop a method of automatic wet chemical analysis. Chlorinated Pesticide Residue. In the analysis of this type of residue, the pesticides are extracted and after a limited "cleanup" process, they are spotted onto a filter paper flag, which is burned in a flask of oxygen.
The chloride formed is absorbed in dilute sulfuric acid and can be estimated colorimetrically by the addition of ferric ammonium sulfate and mercuric thiocyanate; the sensitivity of this method of estimation is approximately 5 J. A more sensitive method is to measure the quantity of chloride produced potentiometrically. This makes the method sensitive down to 0. Recently a new continuous chloride ion system has been developed for use with a completely automated combustion apparatus to determine organochlorine pesticides and their residues.
These methods show the presence or absence of toxicologically significant residues. They are basically useful as sorting methods or for confirming the presence of pesticide residues. Some of the common insects and other organisms that are used in such bioassays are vinegar fly, housefly, mosquito larvae, mites, brine 93 shrimp, daphnia, guppies, and goldfish. These are employed in agricul- ture, forestry, food storage, urban sanitation, and home use.
In cases of accidental occupational poisonings, it has usually been impossible to determine if the exposure was predominantly respiratory or dermal. Of the accidental deaths caused by pesticides in in the United States, five deaths were attributed to respiratory exposure. Of all the pesticides, the chlorinated hydrocarbon and organophosphorous insecticides are of major concern because of their health hazard0 The acute toxicity of the organo-phosphates, on the average, is somewhat greater than that of the chlorinated hydrocarbons,, However, the latter group is considerably more persistent because of their greater stability.
The mean storage level of DDT in the body fat of the general population in the United States in to was reported to be Acute poisonings of commercial and domestic animals have usually been accidental and involved the more toxic organophosphorous insecticides.
Animals also store the chlorinated hydrocarbon residues in fat tissue, and as with humans, the significance of this storage is not completely known. When ingested, as little as 7 to 8 ppm of DDT residue on hay will result in 3 ppm being excreted in cow's milk, and butter made from such milk will contain 65 ppm. Fowl, fish, and many forms of wildlife have been adversely affected by pesticides, especially the chlorinated hydrocarbons.
Birds are affected by DDT resulting in thin- shelled eggs and a decrease in hatchability- Wildlife in general have been affected in various parts of the country. Herbicides may cause damage to other than the target plants if the dosage is too great. Some insecticides have produced undesirable flavors in plants used as food. Trans- location of DDT and other insecticides into crops from the soil has been observed, but apparently this does not result in a high residue level.
The preliminary estimate for places production at slightly in excess of 1 billion pounds, and the manufacturers' value at approximately million dollars. Agriculture is the leading user of pesticides in the United States. Approximately 5 percent of the land area of the United States the 48 contiguous States was treated with insecticides in Cropland and cropland pasture consti- tuted more than 75 percent of the treated area. The primary source of pesticides in the air is the process of application.
Even under the most ideal conditions, some amount will remain in the air following the application. However, under certain meteorological conditions, the pesticide spray or. Many episodes have occurred in which these drifting pesticide clouds have caused inhalation poisonings as well as toxic residues on croplands. It is known that pesticides will volatilize into the air from soil, water, and treated surfaces.
There is good evidence that pesticide-containing dust originating from soil can enter the ambient air and be transported for considerable distances before falling back to the earth. The full significance of" this with respect to effects on the total environment is still not known.
Home use of pesticides has been increasing annually, but little is known about the concentration of pesticides in the home. The air near agricultural areas being treated with pesticides has been monitored and the specific pesticides being used were detected. Detectable amounts of DDT and related insecticides also have been found in the air over urban areas. It has been only recently that an air monitoring network for pesticides has been established so that sufficient data will become available to ascertain the magnitude and dispersion of pesticides in the ambient air.
Preliminary data from nine areas sampled have shown that seasonal and regional variations of pesticide concentrations in the air exist and that the only pesticide common to all of the sampled areas was DDT. The abatement and control measures for prevention of air contamination employed by the chemical industry in general are used in pesticide production facilities. The major problem in pesticide air pollution abatement is in control of pesticide drift during application. The economic and social benefits gained by the use of pesticides have been great.
Pesticides have contributed to the eradication or reduction of a number of human diseases both in the United States and in other parts of the world. It has been estimated that nationally about five dollars are saved for every dollar invested in chemical pesticide usage. Although episodes of damage caused by pesticide drift resulting from agricultural treatment have been reported, no tabulated data on costs of damage due to air pollution from pesticides have been found.
The costs of pesticide air pollution damage to humans, wildlife, and other animals cannot be estimated. The analytical procedures for the determination of pesticides in the environment generally have involved four steps: sampling, extraction, separation, and detection. These procedures have been handicapped in the past by the low pesticide concentrations that must be measured in the ambient air. However, in recent years significant advances have occurred in instrumentation for detection and analysis of low concentrations.
Based on the material presented in this report, further studies are suggested in the following areas: 1 Development of better sampling and analysis methodology and standardization for internal consistency. Abbott, D. Harrison J. Tatton, and J. Abbott, D, C. Harrison, J. O'G, Tatton, and J. Thomson, Organochlorine Pesticides in the Atmosphere, Nature