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DDT

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DDT
DDT molecular structure ball diagram.pngDDT molecular structure sticks diagram.png
General
Systematic name 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane
Molecular formula (ClC6H4)2CHCCl3
SMILES Clc1ccc(cc1)C(c2ccc(Cl)cc2)C(Cl)(Cl)Cl
Molar mass 354.49 g/mol
Appearance waxy solid or colorless crystal
CAS number CAS number::50-29-3
Properties
Density and phase [[Density::1.6 g/cm³]], Solid
Solubility in water 1 mg/100 L (20°C)
Melting point Melting point::108.5°C
Boiling point Boiling point::260°C
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Disclaimer and references


Dichlorodiphenyltrichloroethane, more commonly known as DDT, is a synthetic compound. Created first in 1873 and later reintroduced in 1939, DDT offered the world one of its most potent and effective insecticides ever made. This powerful compound was used freely throughout the world until the early 1970s. However, after careful study and observation, the scientific community deemed dichlorodiphenyltrichloroethane and its degrates to be too harmful for use. One by one nations began banning the production and use of any DDT products. Although some countries still use DDT to this day, dichlorodiphenyltrichloroethane will always have a deadly and toxic legacy. [1]

Properties

Dichlorodiphenyltrichloroethane (DDT) is a compound consisting of hydrogen, carbon, and chlorine. The EPA (Environmental Protection Agency) lists DDT as a Toxicity Class II substance, which means it has a moderate toxicity. When used as an insecticide or pesticide, DDT can exist as aerosols, powders, granules, and in many other forms. However, DDT in its purest form appears as a colorless crystal. [2]

Technical grade DDT, DDT formed with trace amounts of other chemicals, consists of a combination of three isomers: p,p′-DDT (85%), o,p′-DDT (15%), and o,o′-DDT (in trace amounts). This technical-grade of DDT exists as a waxy solid.

Another notable property of DDT is its solubility. In water, DDT is virtually insoluble. In natural solvents, such as ethanol, gasoline, kerosene, peanut oil, and pine oil, this compound can be soluble. DDT is highly soluble in lipids. DDT is also extremely well known for its stability. Once introduced to an environment, dichlorodiphenyltrichloroethane will exist there continually. Even decades after usage, DDT is prevalent within its environment. DDT is not only a dangerously toxic compound, but a long lasting one as well. [3]

Occurrences

DDT Insceticide

Although DDT has been banned in the United States since 1972, it is still prevalent throughout the nation. Due to extensive former use and slowly decomposing nature, DDT still lingers in some regions of our country’s soil, air, water, plant life, animals, and people. Human exposure to DDT usually comes through eating, especially items such as fish, poultry, meat, and leafy and rooted vegetables.

DDT exposure is far higher in regions of the world that still use dichlorodiphenyltrichloroethane or have a diet that includes DDT infected food. One of the highest levels of DDT poisoning in humans is in the indigenous Arctic population that eats their traditional foods such as whale, seal, and caribou. This is because DDT lingers longest within animal fats, such as whale or seal blubber. [3]

DDT and its related compounds are dangerous and long-lasting threats to nature.

Uses

The US Military used DDT during the Korean War (1951) to combat diseases carried by insects, such as malaria.

After discovering DDT’s effectiveness as a pesticide in 1939, DDT production only went up. From 1946 – 1972, DDT was one of the most, if not the most, prominent insecticide in the world. [3]

DDT was used for a variety of things. During WWII, Allied forces used DDT to control mosquitoes infected with malaria and typhus in military and civilian establishments. [2] Following the war, farmers and the agricultural communities looked to DDT as a way to eliminate crop-destroying insects. DDT was proven to kill pink bollworms, codling moths, Colorado potato beetles, and European corn borers. [3] For non-farmers, DDT was an effective way to rid oneself of pesky insects and bugs such as common houseflies, mosquitoes, louses, and lice.

DDT was also used, and still is used to this day in the prevention of insect-carrying diseases. In regions plagued with illness and disease, DDT provides protection from infected insects. Medical professionals have determined that DDT can kill insects carrying diseases such as the bubonic plague, malaria, typhus, dengue fever, elephantitis, encephalitis, leishmaniasis, yaws, sleeping sickness, and yellow fever. The history of Sri Lanka is living proof of the power of DDT insecticides. In 1948, Sri Lanka had 2.8 million medical cases relating to malaria. Then, DDT was introduced into the region. After six years of extensive DDT use, Sri Lanka had only 17 malaria related cases. However, five years after the discontinuation of DDT insecticides the medical cases regarding malaria skyrocketed back up to around 2.5 million. It is because of these numbers and these results that production, distribution, and usage of dichlorodiphenyltrichloroethane is still present throughout the world.

However, DDT’s reign of fame quickly came to a disastrous end. Beginning in the 1960s, people began asking questions and receiving answers concerning the environmental health hazards of DDT. This discomfort and suspicion reached its peak with the release of Silent Spring a novel by American biologist Rachel Carson. She feared that the pesticides that had so effectively killed off insects and pest would begin eliminating other organisms, such as birds, harmless insect species, and plant life. All of theses factors snowballed into a big issue. The final conclusion was the banning of DDT. As of 2012, these are the major nations that have banned the use of DDT: Australia (1967), Sweden (1970), Cuba (1970), The United States of America (1972), Germany (1974), Poland (1976), The United Kingdom (1984), Chile (1985), South Korea (1986), Switzerland (1986), and Canada (1989). [1]

Effects of DDT

These American Robins died in 1961 as a result of DDT poisoning.
In 1963, the predatory bird population rapidly began to dwindle in America. Many implicate DDT and other such pesticides in these fowl deaths.

Ecological Effects

DDT affects animals in a variety of ways depending upon the species and the level of exposure to the compound and its degradates.


Mammals


For mammals, DDT is moderately toxic. Most exposure to this compound comes through oral or dermal routes. Chronic effects produced by DDT in mammals include damage to the nervous system, immune system, liver, kidneys, and the reproductive system. DDT best resides in the mammal’s fat tissue. There, dichlorodiphenyltrichloroethane (DDT) degrades into 1,1-dichloro-2,2-bis(p-dichlorodiphenyl)ethylene (DDE) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), byproducts of DDT.


Fowl


For fowl, DDT is slightly less toxic then it is in mammals. The main way in which birds become exposed to DDT is through the food chain. By consuming lower organism in the food chain, whether fish, mammals, earthworms, or other birds, they run the risk of eating a creature infected with DDT. Chronic exposure to DDT can result in damages to fowl reproduction. One of the main side effects of DDT poisoning is the thinning of eggshells and the deaths of embryos. DDE, a byproduct of DDT, is thought to cause these defects in the reproduction of bird species, especially predatory bird species.


Aquatic Species


DDT is extremely toxic to a wide range of aquatic species including salmon, crayfish, bass, [2] algae, [1] and shrimp. [4] Research has determined that the earliest developmental stages in aquatic creatures is when they are most susceptible to the DDT compound. Also, the bioaccumulation of DDT within the fat tissue of aquatic species chronically exposes them to DDT. This accumulation occurs as a result of constant exposure to DDT through infested sediment, water, plant life, and animal life surrounding the infected creature. For example, a rainbow trout who becomes infected with DDT poisoning will remain exposed to the toxic compound for an estimated 160 days before the DDT is completely eliminated. It is this spreading and increasing of DDT in aquatic species and their environment that is leading to the rise of DDT levels in prominent bodies of water, one example being the Great Lakes. [2]


Insects


DDT has always been a common and effective tool against insects since it was first created into an insecticide in 1939. From flies to moths to mosquitoes, DDT has served to rid people of pesky and deadly insects. However, in recent research, studies have shown that some mosquito populations have developed a resistance to the DDT compound. This poses a great threat to regions in the world plagued by malaria and typhus carrying mosquitoes. In the past DDT has been very successful in ridding countries of mosquitoes, but these new mosquito species could very well threaten an even greater resurgence of disease across the globe. [4]

Environmental Effects

DDT is infamous for its persistent nature. DDT and its decomposing compounds (DDE, DDD) have an approximate half-life of 2-15 years on land, 56 days in large bodies of waters, and 28 days in running water. However, DDT is virtually immobile in soil, runoffs, volatilization, and aerobic and anaerobic movements carry the compound very slowly throughout the soil. DDT and its byproducts thrive best in environments with low volatilization (the physcial change from the liquid to gaseous state), rich organic matter in the soil, and regions of less sunlight. This is seen in how slowly or quickly DDT decomposes. In Arizona, with high volatilization, poor organic matter, and intense sunlight, DDT levels will be reduced in half within 5 months, as opposed to the years that it usually takes to decompose DDT in areas with arable soil and milder climates. [2]

DDT still plagues the world’s environment to this day. First of all, this is because DDT is still used in regions around the globe. However, countries like the United States, which have banned DDT, still have traceable levels of DDT. If the DDT compound is being used anywhere in the world other regions will be affected. Whether through the atmosphere, aquatic animals in the waterways, or the volatilization and decomposition cycle, DDT will spread. [3] It is for these very reasons that the Great Lakes to this day still have DDT in their waters, sediment, plants, and creatures. [5]

Effects on Humans

Dichlorodiphenyltrichloroethane (DDT) is a toxic compound that threatens human life. The extent of the side effects is determined by the amount and length of exposure.

In cases of short term, moderate exposure, people experience irritation (eyes, nose, or throat), nausea, diarrhea, malaise, and increased enzyme activity in the liver. At higher doses, it is possible to experience violent shaking and/or seizures. DDT is dangerous even in the slightest amounts, especially for infants. Children have been poisoned to death by consuming 1 oz. of a 5% DDT kerosene solution. [2]

Some of the more major, long lasting effects of exposure to DDT in humans include: liver damage, impairment of the nervous system, a hindrance to reproduction, damage to the reproductive system, [6] leukemia, diabetes, and can possibly lead to an assortment of cancers including breast, pancreatic [4] liver, and gallbladder cancer. Also, it is still up for debate whether DDT is a carcinogen, a substance that causes cancer in humans. However, many studies have produced results suggesting it does create cancer. Women who have been exposed to high levels of DDT were more inclined to have breast cancer. While this is not solid proof of DDT as a carcinogen, it should also be noted that DDT exists in high concentrations in human milk, much higher than in cow’s milk. [3]

Some claim DDT is not a carcinogenic substance because for it to cause cancer humans would have to be exposed to an unusually high dose of DDT. [2] Others still claim that there is no real scientific proof that DDT causes any health concerns for humans. However, the EPA has come out and declared the DDT compound and its degrates as probable carcinogens. [1] We may not know if DDT causes cancer, but we do know that this compound, once consumed internally, will linger in the human body for over four years. This is a long-lasting, toxic threat that is proven to result in multiple, if not fatal side effects. [4]

References

  1. 1.0 1.1 1.2 1.3 Dichlorodiphenyltrichloroethane. BookRags. Web. Accessed 2 January 2012.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 DDT (dichlorodiphenyltrichloroethane). “Pesticide Management Education Program . Web. Accessed 2 January 2012. Author Unknown.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Sebelius, Kathleen. Dichlorodiphenyltrichloroethane. National Toxicology Program. Web. 10 June 2011.
  4. 4.0 4.1 4.2 4.3 . Proposed dichlorodiphenyltrichloroethane (DDT) use for mosquito control in Uganda; Assessment of possible benefits and effects. “Case Western Reserve University”. Accessed 2 January 2012.
  5. DDT. U.S. Environmental Protection Agency. Web. 18 April 2011. Author Unknown.
  6. DDT. U.S. Environmental Protection Agency. Web. 18 April 2011. Author Unknown.