Development Team
Total Page：16
File Type：pdf, Size：1020Kb
Paper No: 15 Environmental Microbiology & Biotechnology Module: 01 Pesticide Pollution Development Team Prof. R.K. Kohli Principal Investigator & Prof. V.K. Garg & Prof. Ashok Dhawan Co- Principal Investigator Central University of Punjab, Bathinda Paper Coordinator Dr Babita Khosla, , MDU, Rohtak Dr. Anju Content Writer Sciences, Ch. Devi Lal University, Sirsa, Haryana Content Reviewer Dr. Sunil Mittal Central University of Punjab, Bathinda Anchor Institute Central University of Punjab 1 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences Description of Module Subject Name Environmental Sciences Paper Name Environmental Microbiology & Biotechnology Module Name/Title Pesticide Pollution Module Id EVS/EP-XV/01 Pre-requisites After reading and studying this module, you shall be able to: To know about pesticides and their different groups. To gain knowledge about action mechanisms of different pesticides. To learn about the biochemical aspects of pesticides. Objectives To know about harmful impacts of pesticide use. To gain knowledge about environmental cancer caused by the excessive use of pesticides. To analyze prevention and control mechanisms of pesticide pollution. Pesticides, fungicide, pollution, Organochlorine, organophosphates, carbamates, DDT, Keywords 2,4-D 2 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences TABLE OF CONTENTS 1. Learning Outcomes 2. Introduction 3. Classification of various pesticides 3.1 Organochlorines 3.2 Carbamates 3.3 Organophosphates 3.4 Pyrethroids 4. Biochemical aspects of pesticides 5. Effects of pesticides on the environment 5.1 Surface water 5.2 Ground water 5.3 Soil quality 5.4 Air quality 5.5 Pesticides as environmental cancer 6. Summary 7. References 3 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences 1. Learning Outcomes After reading and studying this module, you shall be able to: To know about pesticides and their different groups. To gain knowledge about action mechanisms of different pesticides. To learn about the biochemical aspects of pesticides. To know about harmful impacts of pesticide use. To gain knowledge about environmental cancer caused by the excessive use of pesticides. To analyze prevention and control mechanisms of pesticide pollution. 2. Introduction Pesticides are the chemical substances which are projected to destroy, prevent, deter and weaken the capacity of pests and weeds to compete with desired agricultural crops. The term pesticide comprises insecticides, herbicide, molluscicide, nematicide, rodenticide, avicide, insect repellent, bactericide, fungicide, antimicrobial, sanitizer and disinfectant. Pesticides are broadly used to avoid unwanted pests from attacking desired agricultural crops and livestock which led to their access into different components of the environment. Remarkable benefits have been consequent from the use of pesticides in agriculture, public health, forestry, and the domestic applications. Agriculture is a sector upon which the Indian economy is principally dependent. The applications of pesticides have provided an important aid to agricultural production, increasing yield and crop protection. On the other hand, the detection of pesticide residues in different components of the environment has raised severe concerns regarding the use of chemical pesticides. If the credits of pesticides include enhancement in the economic potential in terms of increase in food, vegetables, fruits and grain production and amelioration of vector-borne killing diseases, then their debits have outcome in severe health problems to man and his environment. The risk groups exposed to chemical pesticides include occupational health hazards, like production workers, formulators, mixers, sprayers, loaders and farmers working in the agriculture sector. Throughout manufacturing and formulation there is high possibility of hazards. In industry workers are at very high risk, since they handle different types of toxic chemicals used in the pesticides making. In recent decades, increasing population has demanded for higher production and improved quality, which has led to increase in the use of chemical pesticides worldwide. Roughly 2 million tons of pesticides are used in the world every year, of which around 24% is used in the United States of America, 45% in the European countries and rest of the world use remaining 25%. However, the quantity of pesticides used in developing countries is much less as compared to developed countries, it is growing progressively and considerably. Extensive use of pesticides for agricultural crops has caused rigorous health hazards and environmental pollution, including cases of acute and chronic human as well as animal poisoning. The introduction of new, advanced and more toxic pesticides into the environment has demanded precise identification of their potential hazards to human health as well as other components of the environment. Pesticides may contaminate and pollute 4 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences water, soil, air and vegetation. In addition to killing and eliminating insects and weeds, they can be toxic and hazardous the host organism as well as other organisms including fish, birds, beneficial insects, non-target organisms and plants. Insecticides are commonly the most toxic class of pesticides; however herbicides can as well create risks to non-target organisms. These toxic chemicals used in the pesticides have become an integral part of the ecosystem, while many of them are remarkably toxic for the physical, chemical and biological segments of the ecosystem. Some pesticides are lipid and fat soluble compounds and they are accumulated in the fatty parts of humans and other animals, such as breast milk, fatty tissues and blood in the food chain. Consequently, human beings are exposed to these micro-pollutants by consuming food-stuff which has been in contact with contaminated water and soil. These pesticides are also extremely toxic to most of aquatic life forms and soil micro-fauna as well as micro-flora. Pesticide Class Target Organism Insecticides Insects or pests Herbicides Weed plants Bactericides Bacteria Fungicides Fungi Nematicides Nematodes Virucides Viruses Miticides Mites Mollusccides Snails Table 1 Pesticide class and target organism 5 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences 3. Pesticide Classification Pesticides are generally classified on the basis of origin, target organism and chemical structure. Pesticides are frequently referred according to their pest control mechanism. Pesticides can also be considered as biodegradable pesticides, which can be broken down by the action of microbes and these are finally converted into harmless compounds and others are persistent chemical pesticides, which may take years before they are finally broken down and there are chances of their entry into food chain. On the basis of their chemical structure pesticides are divided into four major groups, namely organochlorines, carbamates, organophosphates and pyrethroids. 3.1 Organochlorines Organochlorines were the first marketable organic insecticides to be developed. The two major groups of organochlorine insecticides are DDT-type chemical compounds and the chlorinated alicyclics. DDT, Aldrin, Dieldrin, Chlordane, Lindane, Endrin, and Heptachlor are some typical examples of these types of insecticides. Some other examples include mirex, pentachlorophenol and dicofol. DDT is an organochlorine which is generally sprayed to kill the mosquitoes and fight malaria since 1950’s. Organochlorine pesticides can travel a very long distance with air and water. These types of pesticides can be hydrophobic or hydrophilic in nature depending on their molecular structure. Fig. 1 Structure of DDT (Organochlorines group) 6 Environmental Microbiology & Biotechnology Environmental Pesticide Pollution Sciences Fig. 2 Structure of Lindane (Organochlorines group) They function by misbalancing the sodium and potassium ratio of the nerve fiber, directing nerves to transmit endlessly. At the sodium channel, organochlorines stop opening end subsequent to activation and membrane depolarization. Sodium ions leak throughout the nerves and produce a subvert negative after potential with hyper excitability of the nerve membrane. This leakage originates frequent discharges in the neuron impulsively. Their toxicities differ widely, however now a day’s most of them have been phased out because of their persistence nature and bioaccumulation in the food chain. Furthermore, organochlorines are found to be carcinogenic and these types of pesticides are highly resistant to degradation. 3.2 Carbamates Carbamates are organic compound derivative of carbamic acid. Carbamates are available as carbamate ester and carbamic acids and have functional groups that are interconnected structurally and frequently inter-transformed. Esters of carbamates are often called as urethanes. Carbamates are extensively used for the control of pests and worms in the vegetables as well as other crops. Some important carbamate pesticides are propionaldehyde-O-methylcarbamoyl oxinle, aldicarb, carbofuran, baygon, dimetilan, and 2, 3-dihydro-2, 2-dimethy1-7-benzo-furanyl methylcarbamate. The manner of action of the carbamates is the inhibition of cholinesterase. Most widely used carbamate is aldicarb. Carbamates act by inhibiting a key enzyme in central nervous system of insects.