This ninth volume in the Progress in Pesticide Biochemistry and Toxicology series, provides an international outlook on the impact of the production and use of agrochemicals on the environment, In Environmental Behaviour of Agrochemicals emphasis is placed on the methods for assessing the movement of pesticides into ground water from a variety of perspectives, and run-off of agrochemicals from soil into surface water. In addition to detailed accounts of recommended analytical methodologies for environmental samples, an in-depth overview is given of recent developments in the use of computer simulation models for assessing environmental fate.
Coverage also includes the current status of biosensors for in vitro measurements for environmental analysis, volatization of agrochemicals and estimation of physico-chemical properties. Environmental Behaviour of Agrochemicals brings together contributions from internationally renowned experts to discuss a developing topic which is of vital importance to both producers and users of agrochemicals.
About the Author About the Editors He joined Shell Research at Sittingbourne in to work on metabolism of pesticides in plants and soils, and subsequently took responsibility for metabolism, residues chemistry, environmental fate and ecotoxicology activities. In countries of the first world, it has been observed that a diet containing fresh fruit and vegetables far outweigh potential risks from eating very low residues of pesticides in crops Brown, Increasing evidence Dietary Guidelines, shows that eating fruit and vegetables regularly reduces the risk of many cancers, high blood pressure, heart disease, diabetes, stroke, and other chronic diseases.
Lewis attributed doubling in wild blueberry production and subsequent increases in consumption chiefly to herbicide use that improved weed control. The transport sector makes extensive use of pesticides, particularly herbicides. Herbicides and insecticides are used to maintain the turf on sports pitches, cricket grounds and golf courses. Insecticides protect buildings and other wooden structures from damage by termites and woodboring insects. If the credits of pesticides include enhanced economic potential in terms of increased production of food and fibre, and amelioration of vector-borne diseases, then their debits have resulted in serious health implications to man and his environment.
There is now overwhelming evidence that some of these chemicals do pose a potential risk to humans and other life forms and unwanted side effects to the environment Forget, ; Igbedioh, ; Jeyaratnam, No segment of the population is completely protected against exposure to pesticides and the potentially serious health effects, though a disproportionate burden, is shouldered by the people of developing countries and by high risk groups in each country WHO, The world-wide deaths and chronic diseases due to pesticide poisoning number about 1 million per year Environews Forum, The high risk groups exposed to pesticides include production workers, formulators, sprayers, mixers, loaders and agricultural farm workers.
During manufacture and formulation, the possibility of hazards may be higher because the processes involved are not risk free. In industrial settings, workers are at increased risk since they handle various toxic chemicals including pesticides, raw materials, toxic solvents and inert carriers. OC compounds could pollute the tissues of virtually every life form on the earth, the air, the lakes and the oceans, the fishes that live in them and the birds that feed on the fishes Hurley et al.
Certain environmental chemicals, including pesticides termed as endocrine disruptors, are known to elicit their adverse effects by mimicking or antagonising natural hormones in the body and it has been postulated that their long-term, low-dose exposure is increasingly linked to human health effects such as immune suppression, hormone disruption, diminished intelligence, reproductive abnormalities and cancer Brouwer et al.
The magnitude of the toxicity risk involved in the spraying of methomyl, a carbamate insecticide, in field conditions was assessed by the National Institute of Occupational Health NIOH Saiyed et al. Significant changes were noticed in the ECG, the serum LDH levels, and cholinesterase ChE activities in the spraymen, indicating cardiotoxic effects of methomyl. Observations confined to health surveillance in male formulators engaged in production of dust and liquid formulations of various pesticides malathion, methyl parathion, DDT and lindane in industrial settings of the unorganised sector revealed a high occurrence of generalised symptoms headache, nausea, vomiting, fatigue, irritation of skin and eyes besides psychological, neurological, cardiorespiratory and gastrointestinal symptoms coupled with low plasma ChE activity Gupta et al.
Data on reproductive toxicity were collected from 1, couples when the males were associated with the spraying of pesticides OC, OP and carbamates in cotton fields Rupa et al. A study on those affected in the Seveso diaster of in Italy during the production of 2,4,5 T, a herbicide, concluded that chloracne nearly cases with a definite exposure dependence was the only effect established with certainty as a result of dioxin formation Pier et al.
Early health investigations including liver function, immune function, neurologic impairment, and reproductive effects yielded inconclusive results. An excess mortality from cardiovascular and respiratory diseases was uncovered, possibly related to the psychosocial consequences of the accident in addition to the chemical contamination. An excess of diabetes cases was also found. Results of cancer incidence and mortality follow-up showed an increased occurrence of cancer of the gastrointestinal sites and of the lymphatic and haematopoietic tissue.
Results cannot be viewed as conclusive, however, because of various limitations: A similar study in observed no increase in all-cause and all-cancer mortality. However, the results support the notion that dioxin is carcinogenic to humans and corroborate the hypotheses of its association with cardiovascular- and endocrine-related effects Pier et al. During the Vietnam War, United States military forces sprayed nearly 19 million gallons of herbicide on approximately 3.
This effort, known as Operation Ranch Hand, lasted from to Various herbicide formulations were used, but most were mixtures of the phenoxy herbicides 2,4-dichlorophenoxyacetic acid 2,4-D and 2,4,5-trichlorophenoxyacetic acid 2,4,5-T. Approximately 3 million Americans served in the armed forces in Vietnam during the Vietnam War. Some of them as well as some Vietnamese combatants and civilians, and members of the armed forces of other nations were exposed to defoliant mixtures, including Agent Orange.
There was evidence on cancer risk of Vietnam veterans, workers occupationally exposed to herbicides or dioxins since dioxins contaminated the herbicide mixtures used in Vietnam , and of the Vietnamese population Frumkin, In , seven pesticides acephate, chlopyriphos, chlopyriphos-methyl, methamidophos, iprodione, procymidone and chlorothalonil and two groups of pesticides benomyl group and maneb group, i.
An average of about 9 samples has been analysed for each pesticide or pesticide group. For each pesticide or pesticide group, 5. Lettuce was the crop with the highest number of positive results, with residue levels exceeding the MRLs more frequently than in any of the other crops investigated. In , 13 pesticides acephate, carbendazin, chlorothalonil, chlopyriphos, DDT, diazinon, endosulfan, methamidophos, iprodione, metalaxyl, methidathion, thiabendazole, triazophos were assessed in five commodities mandarins, pears, bananas,beans, and potatoes.
Some 6 samples were analysed. Residues of chlorpyriphos exceeded MRLs most often 0. MRLs were exceeded most often in beans 1. Estimation of the dietary intake of pesticide residues based on the 90th percentile from the above-mentioned commodities, where the highest residue levels of the respective pesticides were found, shows that there is no exceeding of the ADI with all the pesticides and commodities studied European Commission, In , four commodities oranges, peaches, carrots, spinach were analysed for 20 pesticides acephate, benomyl group, chlopyriphos, chlopyriphos-methyl, deltamethrin, maneb group, diazinon, endosulfan, methamidophos, iprodione, metalaxyl, methidathion, thiabendazole, triazophos, permethrin, vinclozolin, lambdacyalothrin, pirimiphos-methyl, mercabam.
MRL values were exceeded most often in spinach 7. The intake of pesticide residues has not exceeded the ADI in any case. The exposure ranges from 0. In , four commodities cauliflower, peppers, wheat grains, and melon were analysed for the same 20 pesticides as in the study European Commission, Overall, around samples were analysed.
Residues of methamidophos exceeded MRLs most often 8. The MRL for methamidophos was exceeded most often in peppers and melons The residues of the maneb group exceeded the MRL most often in cauliflower 3. The intake of pesticide residues did not exceed the ADI in any case. It was below 1. The exposure ranged between 0. The intakes for the highest residue levels in a composite sample for chlorpyriphos, deltamethrin, endosulfan and methidathion were below the ARfD for adults. They range between 1. In spite of food contamination, most pesticide deaths recorded in hospital surveys are the result of self-poisoning Eddleston, In India the first report of poisoning due to pesticides was from Kerala in , where over people died after consuming wheat flour contaminated with parathion Karunakaran, The highest level of DDT residues found was 2.
Measurement of chemicals in the total diet provides the best estimates of human exposure and of the potential risk. The risk of consumers may then be evaluated by comparison with toxicologically acceptable intake levels.
Pesticide Chemistry and Toxicology
Fatty food was the main source of these contaminants. In another study, the average daily intake of HCH and DDT by Indians was reported to be and 48 mg per person respectively, which were higher than those observed in most of the developed countries Kannan et al. Pesticides can contaminate soil, water, turf, and other vegetation.
In addition to killing insects or weeds, pesticides can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants. Insecticides are generally the most acutely toxic class of pesticides, but herbicides can also pose risks to non-target organisms. Pesticides can reach surface water through runoff from treated plants and soil. Contamination of water by pesticides is widespread. The results of a comprehensive set of studies done by the U.
Geological Survey USGS on major river basins across the country in the early to mid- 90s yielded startling results. More than 90 percent of water and fish samples from all streams contained one, or more often, several pesticides Kole et al ; Pesticides were found in all samples from major rivers with mixed agricultural and urban land use influences and 99 percent of samples of urban streams Bortleson and Davis, — The USGS also found that concentrations of insecticides in urban streams commonly exceeded guidelines for protection of aquatic life U.
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Twenty-three pesticides were detected in waterways in the Puget Sound Basin, including 17 herbicides. The herbicides 2,4-D, diuron, and prometon, and the insecticides chlorpyrifos and diazinon, all commonly used by urban homeowners and school districts, were among the 21 pesticides detected most often in surface and ground water across the nation U.
Trifluralin and 2,4-D were found in water samples collected in 19 out of the 20 river basins studied Bevans et al.
The herbicide 2,4-D was the most commonly found pesticide, detected in 12 out of 13 streams. The insecticide diazinon, and the weed-killers dichlobenil, diuron, triclopyr, and glyphosate were detected also in Puget Sound basin streams. Both diazinon and diuron were found at levels exceeding concentrations recommended by the National Academy of Sciences for the protection of aquatic life Bortleson and Davis, — Groundwater pollution due to pesticides is a worldwide problem. According to the USGS, at least different pesticides and 21 transformation products have been found in ground water, including pesticides from every major chemical class.
Over the past two decades, detections have been found in the ground water of more than 43 states Waskom, Once ground water is polluted with toxic chemicals, it may take many years for the contamination to dissipate or be cleaned up.
Pesticide Chemistry and Toxicology
A large number of transformation products TPs from a wide range of pesticides have been documented Barcelo' and Hennion, ; Roberts, ; Roberts and Hutson, Not many of all possible pesticide TPs have been monitored in soil, showing that there is a pressing need for more studies in this field. Pesticides and TPs could be grouped into: Pesticides that exhibit such behavior include the organochlorine DDT, endosulfan, endrin, heptachlor, lindane and their TPs. Most of them are now banned in agriculture but their residues are still present. They can be moved from soil by runoff and leaching, thereby constituting a problem for the supply of drinking water to the population.
The most researched pesticide TPs in soil are undoubtedly those from herbicides. Several metabolic pathways have been suggested, involving transformation through hydrolysis, methylation, and ring cleavage that produce several toxic phenolic compounds. The pesticides and their TPs are retained by soils to different degrees, depending on the interactions between soil and pesticide properties. The most influential soil characteristic is the organic matter content.
The larger the organic matter content, the greater the adsorption of pesticides and TPs. The capacity of the soil to hold positively charged ions in an exchangeable form is important with paraquat and other pesticides that are positively charged. Strong mineral acid is required for extracting these chemicals, without any analytical improvement or study reported in recent years.
Soil pH is also of some importance. Adsorption increases with decreasing soil pH for ionizable pesticides e. Heavy treatment of soil with pesticides can cause populations of beneficial soil microorganisms to decline. According to the soil scientist Dr. Overuse of chemical fertilizers and pesticides have effects on the soil organisms that are similar to human overuse of antibiotics. For example, plants depend on a variety of soil microorganisms to transform atmospheric nitrogen into nitrates, which plants can use.
Common landscape herbicides disrupt this process: Mycorrhizal fungi grow with the roots of many plants and aid in nutrient uptake. These fungi can also be damaged by herbicides in the soil. One study found that oryzalin and trifluralin both inhibited the growth of certain species of mycorrhizal fungi Kelley and South, Roundup has been shown to be toxic to mycorrhizal fungi in laboratory studies, and some damaging effects were seen at concentrations lower than those found in soil following typical applications Chakravarty and Sidhu, ; Estok et al.
Triclopyr was also found to be toxic to several species of mycorrhizal fungi Chakravarty and Sidhu, and oxadiazon reduced the number of mycorrhizal fungal spores Moorman, Pesticide sprays can directly hit non-target vegetation, or can drift or volatilize from the treated area and contaminate air, soil, and non-target plants.
Some pesticide drift occurs during every application, even from ground equipment Glotfelty and Schomburg, Despite the fact that only limited research has been done on the topic, studies consistently find pesticide residues in air. Nearly every pesticide investigated has been detected in rain, air, fog, or snow across the nation at different times of the year U.
Many pesticides have been detected in air at more than half the sites sampled nationwide. Herbicides are designed to kill plants, so it is not surprising that they can injure or kill desirable species if they are applied directly to such plants, or if they drift or volatilise onto them. Many ester-formulation herbicides have been shown to volatilise off treated plants with vapors sufficient to cause severe damage to other plants Straathoff, In addition to killing non-target plants outright, pesticide exposure can cause sublethal effects on plants.
Phenoxy herbicides, including 2,4-D, can injure nearby trees and shrubs if they drift or volatilise onto leaves Dreistadt et al. Exposure to the herbicide glyphosate can severely reduce seed quality Locke et al. It can also increase the susceptibility of certain plants to disease Brammall and Higgins, This poses a special threat to endangered plant species.
Fish and Wildlife Service has recognized 74 endangered plants that may be threatened by glyphosate alone U.
About the Author
Exposure to the herbicide clopyralid can reduce yields in potato plants Lucas and Lobb, Some insecticides and fungicides can also damage plants Dreistadt et al. Pesticide damage to plants is commonly reported to state agencies in the Northwest. Plants can also suffer indirect consequences of pesticide applications when harm is done to soil microorganisms and beneficial insects. Pesticides including those of new the generation, e.
Other studies have identified the ability of some of these compounds to undergo short-range atmospheric transport Muir et al. One long-term study that investigated pesticides in the atmosphere of British Columbia BC , dating from Belzer et al. Atrazine, malathion, and diazinon, highly toxic chemicals identified as high-priority pesticides by Verrin et al.
Dichlorvos is a decomposition product of another pesticide, Naled Dibrom Hall et al. Captan and 2,4-D showed the highest concentrations and deposition rates at these two sites, followed by dichlorvos and diazinon Dosman and Cockcraft, Air concentrations of currently used pesticides in Alberta were investigated in at four sampling sites that were chosen according to geography and pesticide sales data Kumar, Triallate and trifluralin were the two mostly detected pesticides at the four sites.
South of Regina, Saskatchewan, in and , 2,4-D reached 3. Triallate, dicamba, bromoxynil concentrations were also higher in peak concentration of 4. In a more recent study, Waite et al. Some acid herbicides were also investigated in South Tobacco Creek, Manitoba during — Once again, maximum concentrations occurred during periods of local use Rawn et al.
A neutral herbicide, atrazine, was also investigated in Rawn et al. Pesticides are found as common contaminants in soil, air, water and on non-target organisms in our urban landscapes. Once there, they can harm plants and animals ranging from beneficial soil microorganisms and insects, non-target plants, fish, birds, and other wildlife. Chlorpyrifos, a common contaminant of urban streams U. Geological Survey, , is highly toxic to fish, and has caused fish, kills in waterways near treated fields or buildings US EPA, Herbicides can also be toxic to fish.
In a series of different tests it was also shown to cause vertebral deformities in fish Koyama, The weed-killers Ronstar and Roundup are also acutely toxic to fish Folmar et al. The toxicity of Roundup is likely due to the high toxicity of one of the inert ingredients of the product Folmar et al. In addition to direct acute toxicity, some herbicides may produce sublethal effects on fish that lessen their chances for survival and threaten the population as a whole.
5.2 People and pesticide poisoning
Glyphosate or glyphosate-containing products can cause sublethal effects such as erratic swimming and labored breathing, which increase the fish's chance of being eaten Liong et al. Several cases of pesticide poisoning of dolphins have been reported worldwide. Because of their high trophic level in the food chain and relatively low activities of drug-metabolising enzymes, aquatic mammals such as dolphins accumulate increased concentrations of persistent organic pollutants Tanabe et al.
Dolphins inhabiting riverine and estuarine ecosystems are particularly vulnerable to the activities of humans because of the restricted confines of their habitat, which is in close proximity to point sources of pollution. River dolphins are among the world's most seriously endangered species.
Populations of river dolphins have been dwindling and face the threat of extinction; the Yangtze river dolphin Lipotes vexillifer in China and the Indus river dolphin Platanista minor in Pakistan are already close to extinction Renjun, ; Perrin et al. In addition to habitat degradation such as construction of dams Reeves and Leatherwood, , boat traffic, fishing, incidental and intentional killings, and chemical pollution have been threats to the health of river dolphins Kannan et al. Earlier studies reported concentrations of heavy metals Kannan et al.
The Ganges river basin is densely populated and heavily polluted by fertilizers, pesticides, and industrial and domestic effluents Mohan, In addition to fish, other marine or freshwater animals are endangered by pesticide contamination. Exposure to great concentrations of persistent, bioaccumulative, and toxic contaminants such as DDT 1,1,1-trichloro-2,2-bis[ p -chlorophenyl]ethane and PCBs has been shown to elicit adverse effects on reproductive and immunological functions in captive or wild aquatic mammals Helle et al.
Aquatic mammals inhabiting freshwater systems, such as otters and mink, have been reported to be sensitive to chemical contamination Leonards et al. EPA, ; Sanders, The weed-killer trifluralin is moderately to highly toxic to aquatic invertebrates, and highly toxic to estuarine and marine organisms like shrimp and mussels U. Since herbicides are designed to kill plants, it makes sense that herbicide contamination of water could have devastating effects on aquatic plants.
In one study, oxadiazon was found to severely reduce algae growth Ambrosi et al. Algae is a staple organism in the food chain of aquatic ecosystems. Studies looking at the impacts of the herbicides atrazine and alachlor on algae and diatoms in streams showed that even at fairly low levels, the chemicals damaged cells, blocked photosynthesis, and stunted growth in varying ways U. Water News Online, The herbicide oxadiazon is also toxic to bees, which are pollinators Washington State Department of Transportation, Herbicides may hurt insects or spiders also indirectly when they destroy the foliage that these animals need for food and shelter.
For example spider and carabid beetle populations declined when 2,4-D applications destroyed their natural habitat Asteraki et al. I specially appreciate his efforts to include a chapter on 'Pesticide Metabolism', which provides the information about the pesticide degradation in very lucid manner and well explained using figures with target site for pesticide metabolism. Pesticide Metabolism is typically a two stage process. Phase I reactions, normally add a functional polar reactive group to the foreign molecule which enables the phase II reaction to take place.
These reactions are catalyzed by the cytochrome P- group of enzymes and other enzymes which are associated with endoplasmic reticulum. Phase I reaction includes microsomal oxidation and extramicrosomal metabolism of pesticides. Phase II reactions are conjugation reactions and involve the covalent linkage of the toxin or phase I product to a polar compound.
In general, conjugated products are ionic, polar, less lipid soluble, less toxic and easily excretable from body. I hope that this book will be very useful to the students of master and graduation level and also to the people working in different fields of pesticide toxicology. As a teacher, I have faced several questions put forward by my students on toxicology such as dose response relationship, carcinogenicity, teratogenicity, mutagenicity, metabolism of toxic chemicals and their behavior in the environment.
These queries initiated me to write a book on "Pesticide chemistry and toxicology", which will provide some answers to their questions. In this book, there are eight chapters with subtopics; each is dealing with answers of very specific questions on toxicology. I have tried to pin point the discrepancies raised in my mind as toxicologist and tried to pen down here.
Thanks to Bentham Science publisher who have made publishing this eBook possible. Home eBooks Bookshelf by Title by Subject.