Fate of Pesticides in the Environment

Fate of Pesticides in the Environment

MINA NEJADAMINBIOM 430 Spring 111OverviewXenobioticsPesticidesFate of pesticides in the environmentAerobic & Anaerobic BiodegradationPesticides as water pollutantsHuman health effects of pesticidesEcological effects of pesticidesPesticide monitoring in surface waterPesticide management and controlXenobioticsstranger to life by its dictionary meaning a chemical that is not produced and found in significant concentrations also does not exist long terms in organisms by its scientific meaningExist in different forms:Certain fertilizers and agrochemicalsEnvironmental contaminants, such as industrial and domestic wastes and effluentsBy-products of biological processes, such as fermentation, distillation and animal productionXenobioticspesticides, Polychlorinated biphenyls (PCBs), dyes, and chlorinated solvents Structurally related, to natural compoundsSuspected of being carcinogenicUsed as industrial solvents, degreasing agents, and insulators in electrical transformers

and thus can be slowly degraded by enzymes that already exist to degrade these natural compounds

They enter anoxic environments through accidental spills or from slow leakage of storage containers or abandoned electrical transformers, and eventually migrate into groundwater, where they are the most frequently detected groundwater contaminants. 4The production rates & major uses of Xenobiotics

Most widely distributed xenobiotics are pesticides.Pesticidesany substance intended to control, destroy, or attract a pest Algicide -- algae Fungicide -- fungi Herbicide -- weeds Insecticide -- insects Miticide --mites Rodenticide rodents

Pesticide Movement

Fate of pesticides in the environmentAdsorptionTransferDegradationMicrobial degradationChemical degradationPhotodegradation

Fate of pesticides in the environmentAdsorption: the adverse attraction between soil particles and chemicalsEffecting factors: organic matter and clay levels in soil, particle surface area, available sites for binding of pesticides, and moistureTransfer: Volatilization, runoff and leaching are the most widely used types Effecting factors: temperature, humidity, air movement, and vapor pressure

Fate of pesticides in the environmentDegradation: breakdown of pesticidesMicrobial degradationChemical degradationPhotodegradationMicrobial Degradation: occurs when microorganisms such as, fungi and bacteria use pesticides as a food sourceoccur rapidly and under the optimum soil conditions that maximize the microbial growthaffected from the pesticides, the frequency of pesticides influence the rapidity

optimum pH levels, amount of organic matter, warm temperatures, convenient soil moisture and also the oxygen uptake

If a specific pesticide is used for number of times in the same field the degradation rapidity increases directly proportional to this. 10Fate of pesticides in the environmentChemical degradation: the breakdown of pesticides with chemical reactions in the soil, living organisms do not involve to the processthe rapidity of the reactions are influenced by temperature, moisture, pH, adsorption, chemical and physical properties of the both pesticide and soilhydrolysis, the pesticide reacts with water during the process

Fate of pesticides in the environmentPhotodegradation: the degradation by using sunlightThe intensity and spectrum of sunlightlength of exposure the properties of the pesticidethe application sitePesticides applied to foliage are more exposed to sunlight than pesticides that are incorporated into the soilAerobic & Anaerobic BiodegradationWHY ANAEROBIC BIODEGRADATION?aerobic processes require oxygen and the oxygen delivery systems used in these processes are very expensive in some conditions such as degradation of contaminated groundwater and PCBs only anaerobic bacteria can be used to gain more efficient processes in most cases in order to make an aerobic degradation process, an anaerobic process is needed primarily Pesticides as water pollutantsThe impact on water qualityis associated with the following factors:

Active ingredient in the pesticide formulationContaminants that exist as impurities in the active ingredientAdditives that are mixed with the active ingredient (wetting agents, diluents or solvents, extenders, adhesives, buffers, preservatives and emulsifiers) Degradate that is formed during chemical, microbial or photochemical degradation of the active ingredient.

The ecological impacts of pesticides in water are determined by the following: criteria:

Human health effects of pesticidesHuman health effects are caused by:Skin contact: handling of pesticide productsInhalation: breathing of dust or sprayIngestion: pesticides consumed as a contaminant on/in food or in waterFor the majority of the population, a principal vector is through ingestion of food that is contaminated by pesticides Degradation of water quality by pesticide runoff has two principal human health impacts consumption of fish and shellfish that are contaminated by pesticidesthe direct consumption of pesticide-contaminated waterFarm workers have special risks associated with inhalation and skin contact during preparation and application of pesticides to crops

WHO (1993) has established drinking water guidelines for 33 pesticides (Annex 1). Many health and environmental protection agencies have established "acceptable daily intake" (ADI) values which indicate the maximum allowable daily ingestion over a person's lifetime without appreciable risk to the individual. For example, in a recent paper by Wang and Lin (1995) studying substituted phenols, tetrachlorohydroquinone, a toxic metabolite of the biocide pentachlorophenol, was found to produce "significant and dose-dependent DNA damage".

16Ecological effects of pesticidesBioconcentration: The movement of a chemical from the surrounding medium into an organismBiomagnification: The increasing concentration of a chemical as food energy is transformed within the food chainVery high concentrations can be observed in top predators, including manThe important point is that many of these effects are chronic (not lethal), are often not noticed by casual observers, yet have consequences for the entire food chain The primary "sink" for some pesticides is fatty tissue ("lipids"). Some pesticides, such as DDT, are "lipophilic", meaning that they are soluble in, and accumulate in, fatty tissue such as edible fish tissue and human fatty tissue

Death of the organism. Cancers, tumours and lesions on fish and animals. Reproductive inhibition or failure. Suppression of immune system. Disruption of endocrine (hormonal) system. Cellular and DNA damage. Teratogenic effects (physical deformities such as hooked beaks on birds). Poor fish health marked by low red to white blood cell ratio, excessive slime on fish scales and gills, etc. Intergenerational effects (effects are not apparent until subsequent generations of the organism). Other physiological effects such as egg shell thinning.

17Pesticide monitoring in surface waterMonitoring data for pesticides are generally poor in much of the world and especially in developing countries Many developing countries have difficulty carrying out organic chemical analysis due to problems of inadequate facilities impure reagentsfinancial constraints New techniques using immunoassay procedures for presence/absence of specific pesticides may reduce costs and increase reliabilityPesticide management and controlExamples & ExperiencesThe European experience

The Netherlands National Institute of Public Health and Environmental Protection concluded that "groundwater is threatened by pesticides in all European states. This is obvious both from the available monitoring data and calculations concerning pesticide load, soil sensitivity and leaching It has been calculated that on 65% of all agricultural land the standard for the sum of pesticides (0.5; m g/l) will be exceededIn recognition of pesticide abuse and of environmental and public health impacts the European countries have adopted a variety of measures that include (FAO/ECE, 1991):Reduction in use of pesticides (by up to 50% in some countries) Bans on certain active ingredientsRevised pesticide registration criteriaTraining and licensing of individuals that apply pesticidesReduction of dose and improved scheduling of pesticide application to more effectively meet crop needs and to reduce preventative spraying Testing and approval of spraying apparatus. Limitations on aerial spraying Environmental tax on pesticides. Promote the use of mechanical and biological alternatives to pesticides

19Examples & ExperiencesThe Danish example

In 1986 the Danish Government initiated an Action Plan for sustainable agriculture which would prevent the use of pesticides for two purposes (WWF, 1992)Safeguard human health Protect the environmentThe objective was to achieve a 50% reduction in the use of agricultural pesticides by 1997 from the average amount of pesticides used during the period 1981-85 This was to be measured by a decline in total sales (by weight) of the active ingredients and, decrease in frequency of application

SummaryPesticides can have a negative influence on environment especially water resources, public health and wildlifeBe aware of the possible means of the pesticide transport from the target site to an off target sitecommon sense, concerning handling, mixing, applying and disposing of pesticides and pesticide containersFollow labeled directions in order to minimize risk associated with negative pesticide affects on the environment and public healthWorks cited:1- Corbett, J. R. The Biochemical Mode of Action of Pesticides. London: Academic, 1974. Print.2- Goodman, B. A., Late M J. Allison, K. J. Oparka, and J. R. Hillman. "Xenobiotics: Their Activity and Mobility in Plants and Soils." Journal of the Science of Food and Agriculture 59.1 (1992): 1-20. Print.3- Zhang, Chunlong, and George N. Bennett. "Biodegradation of Xenobiotics by Anaerobic Bacteria." Applied Microbiology and Biotechnology 67.5 (2005): 600-18. Print.4- Hill, David W., and Perry L. McCarty. "Anaerobic Degradation of Selected Chlorinated Hydrocarbon Pesticides." Water Pollution Control Federation 39.8 (1967): 1259-277. Print.5- Barnard, C., S. Daberkow, M. Padgitt, M. Smith, and N. Uri. "Alternative Measures of Pesticide Use." Science of The Total Environment 203.3 (1997): 229-44. Print.6- Fishel, Fred. "Pesticides and the Environment." MU Guide 91.9: 1-6. Print.7- Matsumura, Fumio, and Murti C. R. Krishna. Biodegradation of Pesticides. New York: Plenum, 1982. Print.8- Kuhr, Ronald J., and Naoki Motoyama. Pesticides and the Future: Minimizing Chronic Exposure of Humans and the Environment. Amsterdam: IOS, 1998. Print.9- Menzie, C. M. "Fate of Pesticides in the Environment." Annual Review of Entomology 17.1 (1972): 199-222. Print.10- Arnold, D. J., and G. G. Briggs. "Fate of Pesticides in Soil: Predictive and Practical Aspects." Progress in Pesticide Biochemistry and Toxicology 7 (1990): 101-22. Print.11- Mogensen AS, Haagensen F, Ahring BK (2003b) Anaerobic degradation of linear alkylbenzene sulfonate. Environ Toxicol Chem 22:70671112- Schink B (2002) Anaerobic digestion: concepts, limits and per- spectives. Water Sci Technol 45:1813- Baker KH, Herson DS (1994) Bioremediation. McGraw Hill, New York, NY14- Master ER, Lai VW-M, Kuipers B, Cullen WR, Mohn WW (2002) Sequential anaerobic-aerobic treatment of soil contaminated with weathered Aroclor 1260. Environ Sci Technol 36:10010315- Williams PP (1977) Metabolism of synthetic organic pesticides by anaerobic microorganisms. Residue Rev 66:63135

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