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DDT or Dichloro-diphenyl-trichloroethane (
DDT was developed as the first of the modern insecticides early in World War II. It was initially used with great effect to combat mosquitoes spreading malaria, typhus, and other insect-borne human diseases among both military and civilian populations. [1]
In the early 1960s, Rachel Carson, through publication of the book Silent Spring, aroused public opinion against DDT with her claim that DDT caused cancerFor other meanings of Cancer: see Cancer (disambiguation . apoptosis; cancer cells, however, avoid apoptosis. Cancer is a group of related diseases characterized by uncontrolled cell division. Currently, it is believed that cancers arise from both genetic and harmed bird reproduction by thinning egg shells; the resulting outcry eventually led to the pesticide being banned for agricultural use worldwide and was one of the signature events in the birth of the environmental movementEnvironmentalism is activism aimed at improving the environment, particularly nature. This activism is usually based on the ideology of an environmental movement, and often takes the form of public education programs, advocacy, legislation and treaties..
DDT is created by the reaction of trichloromethanal with chloro benzeneBenzene Chemical nameBenzene Chemical formulaCH Molecular mass78. 11 g/mol Density0. 8786 g/ml Melting point5. 5 °C Boiling point80. 1 °C Heat of vaporization44. 3 kJ/mol Heat of fusion9. 84 kJ/mol CAS number71-43-2 SMILESC1 CC CC C1 Benzene PhH or benzol (C6H5Cl). Trade or other names for DDT include Anofex, Cesarex, Chlorophenothane, Dedelo, p,p'-DDT, Dichlorodiphenyltrichloroethane, Dinocide, Didimac, Digmar, ENT 1506, Genitox, Guesapon, Guesarol, Gexarex, Gyron, Hildit, Ixodex, Kopsol, Neocid, OMS 16, Micro DDT 75, Pentachlorin, Rukseam, R50 and Zerdane.
DDT is persistent in the environmentAn environment is a complex of external factors that acts on a system and determines its course and form of existence. An environment may be thought of as a superset, of which the given system is a subset. An environment may have one or more parameters, p, with a reported half life of between 26 days in river water (U.S. EPA, 1989) to 15 years and is immobile in most soilSoil is the layer of minerals and organic matter, in thickness from centimetres to a metre or more, on the land surface. Its main components are mineral matter, organic matter, moisture, and air. Soils differ in the ratio of these components. Modern soils. Routes of loss and degradation include runoff, volatilization, photolysis and biodegradationBiodegradation is the decomposition of material by microorganisms. It is often used in sewage treatment. Biodegradable matter is material that can be biodegraded. For example, most plastic bags are not biodegradable, but paper bags are. In managing waste (aerobic and anaerobic). These processes generally occur slowly. Breakdown products in the soil environment are DDE (1,1-dichloro-2,2-bis(p-dichlorodiphenyl)ethylene) and DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane), which are also highly persistent and have similar chemical and physical properties.
DDT was first synthesized in 1873, and its insecticidal properties were discovered by the Swiss scientist Paul Hermann Müller in 1939 who was awarded the 1948 Nobel Prize in Physiology and Medicine for his efforts. DDT is the best known of a number of chlorine-containing pesticides used in the 1940s and 1950s. It was extensively used during World War II among Allied troops and certain civilian populations to control insect typhus and malaria vectors. Entire cities in Italy were dusted to control the typhus carried by lice. DDT was also extensively used as an agricultural insecticide after 1945. In the 1950s, in some uses doses of DDT and other insecticides had to be doubled or tripled as some resistant insect strains developed, and evidence began to grow that the chemical was concentrated in the food chain.
Civilian suppression of typhus and malaria vectors (mosquitoes) uses a spray on interior walls, which kills mosquitoes which rest on the wall, while resistant strains are repelled from the area, and thus humans are protected. The compound is stable and concentrates in fatty tissue, reaching dangerous levels in carnivores high in the food chain. It is also excreted in milk.
DDT was responsible for eradicating malaria from Europe and North America. Though today malaria is thought of as a tropical disease, it was more widespread prior to an extensive malaria eradication program carried out in the 1950s. Though this program was highly successful worldwide (reducing mortality rates from 192 per 100,000 to a low of 7 per 100,000), it was less effective in tropical regions due to the continuous life-cycle of the parasite and poor infrastructure. It was not pursued aggressively in sub-Saharan Africa due to perceived difficulties, with the result that mortality rates there were never reduced to the same dramatic extent, and now constitute the bulk of malarial deaths worldwide, especially following the resurgence of the disease as a result of insect resistance to DDT, microbe resistance to drug treatments and the spread of the deadly malarial variant caused by Plasmodium falciparum.
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