Pesticides as Water Pollutants - Assignment Example

 Pesticides as Water Pollutants Introduction Pesticide is a composite term that includes all chemicals which are used to kill or control a wide variety of organisms and pets in agricultural field to increase the quality and quantity of food crops. Pesticide production and usage is one of the fundamental contributors to the Green Revolution. The American Chemical database claimed in 1993 that around 13 million chemicals were found and are adding with the rate of 500,000 every year. For instance, in North America, the Great Lakes are found to have 200 chemicals of concern in water and sediments of the ecosystem (Hamilton 63-65). Both agricultural and non-agricultural toxic compounds causing bad effects on ecological and human health; however, it is difficult to separate these effects caused from those compounds which are intentionally released by the industries as by-products or waste materials. Nevertheless, there is wide evidence that agricultural use of pesticides has a major impact on water quality and leads to serious environmental and human health problems. Factors affecting toxicity of pesticide in water Many factors of pesticides affect the quality of water causing it more toxic, degrading and lethal 1. Toxicity Concentration of the pesticide which is enough to kill half of the test organisms in a specific test period is termed as lethal dosage (“Pesticides as Water Pollutants”). The lethal dose is inversely proportional to toxicity. Thus, the lower the lethal dosage is, the higher is the toxicity. Values ranging from 0-10 are considered as extremely toxic. Toxic response can be life threatening or chronic, causing severe health problems, for instance, cancer, infertility, hormonal imbalance, digestive problem, etc. 2. Persistence Persistence is measured by the half-life of a pesticide. It is very important to find out about the persistency of a pesticide since it gives an idea about how poisonous a pesticide can be. Persistency is inversely proportional to lethality of a pesticide, that is, the more the persistency is, the lesser is the pesticide lethal (“Pesticides as Water Pollutants”). 3. Degradation The eroding of pesticides into other products can lead to many other problems. The newly formed by-products can have different persistency, and lethality that can totally change the surrounding in which they are present. One of the examples is DDT. When it is degraded, it forms other substance (DDD and DDE) which have totally different persistency and risks. Chronology of pesticide development The impact on water pollution is related mainly to the active ingredient present in the pesticide formulation. However, additives that are used to prepare the final formulation that include wetting agents, diluents, solvents, buffers, emulsifiers, preservatives and adhesives can be the cause of water contamination. Other than the agents used for the preparation of pesticides, degrades and the by-products formed during its usage can also contaminate water and lead to water pollution. Below are the details in chronological order of various pesticides, their sources and characteristics that have been used for many years and led to water pollutions. From 1800 to 1920 In the early period, the most useful pesticides were petroleum oils, nitro-phenols, naphthalene, chlorophenols, and creosote. These products were non-specific in nature, thus causing toxicity in targeted as well as non-targeted organisms. The source of these compounds was either laboratory preparation or by-products of coal gas productions. From 1945 to 1970 Many products that were used during this period were organically synthesized. Pesticides like chlorinated organic, chlorinated cyclodienes, HCCH, and DDT were persistent in nature and had a wide range of selectivity among different organisms whereas pesticides like organophosphorus compounds, carbamates, and cholinesterase inhibitors had lower resistance and caused not only user toxicity but serious water contamination and ecological problems. From 1970-1985 Pesticides like synthetic biological pesticides which lacked selectivity pyrethroids, hormonal mimics and avermectins had variable persistence. They were prepared with the help of an advanced procedure that causes the structural refinements in the parent compound. From 1985 till today This was modern period for pesticide that selectively targeted the organisms by genetically engineered products. These are mostly genetically engineered organisms and have their own gene specificity. However, later mutations in such organisms have been seen causing disruption in microbiological products and various contaminations (“Pesticides as Water Pollutants”). Types of Pesticides Pesticides are chemical agents and can be differentiated by their specific chemical properties, structures, and characteristics. They can be grouped as per their control but mostly by the common source. Some examples of chemically-related pesticides are: 1. Organophosphate pesticides These are pesticides affecting a person’s nervous system disrupting acetylcholine (the enzyme neurotransmitter produced in human body to convey messages). Most of these chemicals are insecticides. The effect of these pesticides on insects is same on humans, which can cause many problems if misused. Presence in water is less as they are less persistent in the environment. 2. Carbamate pesticides Carbamate pesticides work the same way as organophosphates pesticides do. They act on the nervous system and distort the activity of the neurotransmitter in the nervous system, acetylcholine. 3. Organochlorine insecticides These pesticides have a highly persistence and have serious effect on human health and environmental effects that usually include water contamination. The most common examples are DDT and chlordane. Organochlorine insecticides have been removed from the market because of its high persistency. 4. Pyrethroid pesticides Pyrethrin is a naturally occurring pesticide found in chrysanthemums. Chemists later developed a synthetic version of pyrethrin which was called pyrethroid. They were modified to be more stable in the environment; however, some are very toxic to human nervous system. Pesticides Affects on Human Health Pesticide contamination can cause serious human health effects also. Following below are some of the major problems arising from pesticides. 1. Skin Contact: Direct or indirect contact with pesticide can lead to many skin diseases that range from minor skin allergies to severe carcinomas depending upon the lethality of a pesticide. 2. Inhalation: Inhaling a pesticide can cause serious breathing problem and even asthma. 3. Ingestion: Ingestion of a pesticide directly or indirectly causes nausea, vomiting and diarrhea. Individuals who are in direct contact with pesticides have a higher risk to be affected by the pesticide contamination, especially farm workers. Other than farmers, inhabitants who are ingesting the contaminated food can also be affected and suffer from severe health problems. Effects on water contamination The impact of pesticide in water pollution and contamination is quite diverse. It ranges from mild and moderate to severe risk, depending on their persistency. However, the earthly effects by pesticides are widely present, and the most prominent one among them is contamination of water. The two main procedures that need to be considered in this regard are as follows Bioconcentration The transfer of a chemical from the surrounding environment into an organism’s body is called as Bioconcentration. For pesticides ‘lipids’ (fatty tissues) are the first attraction in which they can absorb. Most of the pesticides are lipophilic in nature. Lipophilic substances have the tendency to dissolve and mix up in fatty tissues in a body. So if these lipophilic pesticides are present in water they will absorb in the bodies of edible fish and human tissues. Once absorbed they may cause serious problems while other may get digested and thrown out of the body, for instance, glyphosate. 1. Biomagnification All the organisms in the nature are dependent on each other for food to make enough energy for their living. When an organism in the lower compartment of the food chain is eaten by the one in the higher compartment, it takes all the contents of the smaller organisms including any chemical, if present. Thus, organisms have a higher chance to be affected by such substances since they accumulate a lot of food. For instance, eating a lot of fish that is exposed to high lipophilic pesticide in the water will ultimately affect his tissues. This transference of chemical in the higher animals is called biomagnification (“Pesticides as Water Pollutants”). . Conclusion The effect of the pesticide in a water environment is an early alarm to a community of the upcoming health hazards, which can be acute and chronic. Most of the times they are not noticed by the casual observers; still, the consequences for the entire chain can be very dangerous. Efforts are being made to minimize the usage of pesticide or find the alternatives. In this regard, many laws have been implemented that prohibit the usage of very toxic substance, training and licensing of individuals to use the pesticides, reduction of dosage, and environmental tax on pesticides. Many ecologists also promote the use of mechanical and biological altervatives to pesticides that can help in minimizing the risk it brings to the ecology and human health. Works Cited “Pesticides as Water Pollutants." Pesticides as Water Pollutants. Natural Resources Management and Environment Department, 1996. Web. 29 Mar. 2013 Hamilton, Denis, and Stephen Crossley. Pesticide Residues in Food and Drinking Water: Human Exposure and Risks. New York: J. Wiley, 2004. 63-65. Print. Read More