DDT Full Form and Chemical Formula
DDT is also called DDT 223, the chemical name and DDT Full Form is Dichlorodiphenyltrichloroethane, and the chemical formula (ClC6H4)2CH (CCl3) is an organochlorine insecticide. It is a white crystal, insoluble in water, soluble in kerosene, and can be made into an emulsion.
It is an effective insecticide. It has played a significant role in preventing agricultural pests and diseases in the first half of the 20th century and reducing the risk of diseases caused by mosquitoes and flies such as malaria and typhoid fever.
However, due to its excessive environmental pollution, many countries and regions have banned it. The World Health Organization announced in 2002 that DDT was reactivated to control mosquito breeding and prevent malaria, dengue fever, yellow fever, and another worldwide resurgence.
On October 27, 2017, the World Health Organization’s International Agency for Research on Cancer published a preliminary list of carcinogens, 4, 4′-dichlorodiphenyltrichloroethane (DDT) in the list of Class 2A carcinogens.
National Standard Number: 61876
CAS No.: 50-29-3
Chinese name: DDT
English name: 2, 2-bis(4-Chlorophenyl)-1,1,1-trichloroethane
Alias: 2, 2-bis(4-chlorophenyl)-1,1,1-trichloroethane (ie p,p’-DDT);
Major isomers and homologs: o,p’-DDT; p,p’-DDE;p,p’-DDD
Molecular formula: C14H9Cl5
Appearance and traits: All isomers of DDT compounds are white crystalline solid or light yellow powder, tasteless, almost odorless
Molecular weight: 354.5
Steam pressure: 2.53 × 10 -8 kPa / 20 ° C
Flash point: 72 ~ 77 ° C
Melting point: 108～109°C
Boiling point: 260 ° C
Solubility: DDT is extremely insoluble in water. The solubility in organic solvents is as follows (g/100mL): benzene is 106, cyclohexanone is 100, chloroform is 96, petroleum solvent is 4-10, and ethanol is 1.5.
Density: 1.55 (25 ° C)
Stability: DDT is chemically stable and does not decompose at room temperature. Stable to acids, strong bases and iron-containing solutions tend to promote their decomposition. When the temperature is higher than the melting point, especially in the presence of a catalyst or light, the dehydrochlorination of p,p’-DDT forms DDE.
Danger mark: 14 (with drugs)
Main use: used as an agricultural pesticide
Chronic poisoning symptoms in the population include loss of appetite, pain in the upper abdomen and right flank, headache, dizziness, muscle weakness, fatigue, insomnia, vision and speech disorders, tremors, anemia, and weakened deep limb reflexes. There are liver and kidney damage, skin lesions, heart arrhythmia, weak heart sounds, sinus bradycardia, bundle branch block, and myocardial damage.
11～20mg/kg.d, mice oral, 2 years, the risk of liver cancer increased by 4.4 times 0.16～0.31mg/kg.d, mice oral, 2 generations, and the risk of the male liver tumor increased by 2 times, female Not changed in the middle.
Liver tumors were induced in mice (also possible in rats) with DDT, DDE, and DDD, but there are disagreements about the significance of these tumors. According to the data, there is no evidence to prove that DDT is carcinogenic to humans. Laws et al. (1967) investigated a large number of 35 workers exposed to DDT at a DDT manufacturing facility and found no cancer or blood disease.
In the 19 years since the factory was opened, the number of staff has increased from 111 to 135, and no cancer patient has been seen. The United States has used DDT extensively since 1942. DDT Full Form
According to its results for total mortality of liver and hepatobiliary cancer, there has been a significant downward trend, from 8.8 in 1930 to 8.4 in 1944, to 5.6 in 1972 (both at 100,000). Artificial base count). There is no evidence that liver cancer has increased in the decades following the use of DDT.
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In the experimental study of DDT action, studies on mouse rats and dogs did not show any teratogenic effects.
There is sufficient evidence that DDT has no mutagenic effects in bacterial systems that are activated by and without metabolism, and there is no definitive conclusion from the evidence obtained from mammalian experimental systems (both in vivo and in vitro). And the significance of DDT to human mutagenicity is still unclear.
There are two main aspects to the degradation of DDT in the human body. One is to remove hydrogen chloride to form DDE. The conversion of DDT to DDE in the human body is relatively slow, and the DDT converted to DDE in 3 years is less than 20%.
A DDT survey of fats stored in US nationals in 1964 showed that the total amount of DDT was 10 mg/kg, of which about 70% was DDE. DDE emissions from the body were particularly slow, and the biological half-life was about 8 years.
DDT can also be used to generate DDD by primary reduction, which is simultaneously converted to DDA which is more soluble in water and eliminated. Its biological half-life is only about 1 year. DDT Full Form
DDT in the environment or undergoes a series of more complex biological and environmental degradation changes, the main reaction is the removal of hydrogen chloride to form DDE. DDE is less toxic to insects and higher animals and is hardly biodegraded and thus DDE is the main residue stored in tissues.
In biological systems, DDT can also be reductively dechlorinated to form DDD, which is not as stable as DDT or DDE and is the first step in the degradation pathway in animals and the environment.
DDD is dehydrochlorinated to form DDMU [chemical name: 2,2-bis-(p-chlorophenyl)-1-vinyl chloride], which is then reduced to DDMS [chemical name: 2,2-bis-(p-chlorophenyl) 1–1-chloroethane], then dehydrochlorination to form DDNU [chemical name: 2,2-bis-(p-chlorophenyl)-ethane], final oxidation of DDA [chemical name: bis-(p-chlorophenyl) ) acetic acid].
This compound has a greater solubility in water than DDT and is the final excretion product of DDT ingested and stored by higher animals and humans. In the environment, DDT residues can be converted to p-dichlorobenzophenone.
DDT can also be degraded to a lesser extent by microparticle oxidase, reacting at the α-H position to form Kelose. Scientists have discovered a new anaerobic degradation pathway, especially in sludge that can be converted to DDCN by chemical bacteria [chemical name: bis-(p-chlorophenyl)acetonitrile].
DDT disappears slowly in the soil environment and generally takes about 10 years. DDT Full Form
The results of the study demonstrate that DDT can be degraded into carbon dioxide and hydrochloric acid under conditions similar to high-altitude atmospheric laboratory conditions.
DDT has high stability and durability, and DDT evaporation can still be detected in farmland after 6 months of treatment. DDT pollution is spread all over the world. Traces of DDT can still be detected from dust drifting 1000 kilometers or more in snow water dissolved from the Antarctic.
In general, the concentration of DDT in the air of non-agricultural areas is less than 1 to 2.36 × 10 -6 ng / m3, and the concentration range of agricultural residential areas is 1 to 22 × 10 -6 ng / m3. The concentration of DDT in the residents was higher and was recorded as high as 8.5×10 -3 mg/m3.
In agricultural areas and remote non-agricultural areas, the concentration of DDT in rainwater is often in the same order of magnitude (1.8 × 10 -5 to 6.6 × 10 -5 mg / L).
This indicates that the distribution of the compound in the air is fairly uniform. The concentration of DDT in the surface water is related to the level of DDT in rainwater and soil. The highest concentration detected in drinking water in the United States in 1960 was 0.02 mg/L.
The concentration of DDT found in soil without DDT was 0.10-0.90 mg/kg, which was only slightly lower than the concentration in cultivated soil (0.75-2.03 mg/kg) with 10 or more years of DDT. Most of the DDT is present in the soil 2.5 cm deep in the surface layer.
DDT easily accumulates in the fat of humans and animals. After repeated administration, the accumulation of DDT in adipose tissue is initially large and gradually slows down to a stable concentration. Like most animals, people can turn DDT into DDE. DDE is more easily accumulated than its parent compound.
According to most reports, the total DDT content in the blood of the general population in different countries ranges from 0.01 to 0.07 mg/L, with the highest average being 0.136 mg/L. DDT Full Form
The DDT content in human milk is usually 0.01 to 0.10 mg/L. If the content of DDT is added to the content of its metabolite (especially DDE), it is about 1 times higher than the above content.
The average content of DDA in the urine of the general population is about 0.014 mg / L. Under normal circumstances, occupational exposure makes the average accumulation concentration of DDT and total DDT in fat reach 50-175 mg/kg and 100-300 mg/kg, respectively.
Fish and shellfish have a strong enrichment effect on DDT. For example, oysters can increase the DDT content in their bodies to 70,000 times the amount of water in the surrounding seawater.
The amount of DDT in the human body varies with the source of the food and the working environment. DDT Full Form
DDT is a highly fat-soluble organic compound. A relatively consistent understanding is that the amount of DDT remaining in various organs of the human body is positively correlated with the fat content of the organ.
The pathways of DDT transformation in the environment include photolysis transformation, biotransformation, soil transformation and the like. In addition to metabolic transformation in mammals, there are also different transformation pathways such as birds, insects, higher plants and microorganisms in biotransformation. Up to now, there have been nearly 20 kinds of transformation substances (including mammalian metabolites). Identification, but the chemical structure of many other compounds remains unclear. The toxicological properties of these transformation products are almost ignorant except for major products such as DDE and DDD.
There is still a considerable gap in the understanding of the cycle and outcome of DDT and its homologues throughout the environment.
- Dangerous characteristics
In case of fire, high heat is flammable. Decomposed by high heat, releasing toxic fumes.
- Combustion (decomposition) product
Carbon monoxide, carbon dioxide, hydrogen chloride.
Mild poisoning can cause headache, dizziness, weakness, sweating, insomnia, nausea, vomiting, and occasional tremors in the hands and fingers.
Severe poisoning is often accompanied by high fever, sweating, vomiting, diarrhea; nervous system excitement, upper and lower limbs and facial muscles are tonic convulsions, epilepsy-like convulsions, seizures; respiratory disorders, dyspnea, purpura, sometimes lungs Edema, even respiratory failure; liver and kidney damage, liver enlargement, liver function changes; oliguria, no urine, protein in the urine, red blood cells, etc.; skin irritation can occur redness, burning, itching, but also There is dermatitis, such as splashing into the eyes, can make the eyes temporarily blind.
DDT is generally toxic to hexachlorocyclohexane and is a neurotoxic agent of the nervous and parenchymal organs. It has moderate to acute toxicity to humans and most other organisms. DDT Full Form
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It can be absorbed through the skin and is a typical representative of contact poisoning. Because it has certain evaporation even under normal pressure at 12 ° C or lower, inhalation of DDT vapor can also cause poisoning.
When DDT poisoning is discovered, the following first aid measures can be taken:
Acute poisoning must first remove the poison. Oral poisoning should immediately induce vomiting, and gastric lavage with 2% sodium bicarbonate solution, water or 0.5% medicinal charcoal suspension.
After gastric lavage, sodium sulfate and magnesium sulfate laxatives are used for catharsis. Oily laxatives should not be used to avoid drug absorption.
Inhalation poisoning or skin or eye infections should promptly leave the patient, inhale the fresh air, wash the skin with soapy water or soda water, apply hydrocortisone ointment, rinse eyes with water or 2% soda water, and A drop of procaine hydrochloride eye drops to relieve pain.
For the symptoms of convulsions, apply 10% chloral hydrate 15~20mL enema, or use 5~5ml of paraformaldehyde for intramuscular injection.
At the same time, add 10% calcium gluconate 10mL to add 20~40mL intravenous glucose to the intravenous vein to supplement blood calcium. Once every 4 to 6 hours until the convulsion stops.
Intravenous infusion of 10% glucose solution or 5% glucose normal saline, supplemented with water shortage to strengthen nutrition, with multivitamin B drugs to protect the liver, eating high protein diet.
DDT is a medium-intensity toxic chemical that can enter the human body in multiple ways and produce toxic effects. DDT Full Form
Therefore, in the production and transportation of DDT, it is necessary to take appropriate precautions to prevent the operator’s mouth, respiratory tract and skin contact and endanger the health of the operator.
In order to avoid the pollution of DDT to the environment and transportation tools during transportation, and to prevent the occurrence of poisoning incidents, the maritime organizations of various countries suggest that DDT is toxic and hazardous, and needs to be packaged and stored with toxic substances; it cannot be mixed with foods such as grain. It should be shipped separately; the DDT must be removed from the DDT-loaded vehicle.
Due to the high residue of DDT and the potential hazards to the environment and even the ecosystem, many countries in China, Japan, Europe, and the United States have banned the use of scales and regulations or prescribed strict use procedures. DDT Full Form
The source of DDT pollution has been basically controlled. However, it is difficult to estimate when the DDT residue in the environment and in the organism can be completely removed. Even though appropriate substitutes have not yet been found, some have thought that mosquitoes that transmit malaria in the tropics will continue to use DDT in the future.
Therefore, it is appropriate to be vigilant about the environmental problems caused by DDT.
First, leakage emergency treatment
Isolation of the leaking contaminated area, with warning signs around it, it is recommended that emergency personnel wear gas masks and chemical protective clothing. Do not touch the spill directly, avoid dust, collect in a dry, clean, covered container, and transfer to a safe place. It can also be rinsed with a large amount of water, and the diluted wash water is placed in the wastewater system. Such as a large number of leaks, collected or recycled or discarded after harmless treatment.
Second, protective measures
Respiratory protection: Respirators should be worn during production or agricultural use. Self-contained breathing apparatus should be worn during emergency rescue or escape.
Eye protection: Wear chemical safety glasses.
Protective clothing: Wear appropriate protective clothing.
Hand protection: Wear protective gloves.
Others: Smoking is prohibited at the work site and food is consumed. After work, shower and change clothes. Do not bring work clothes to non-workplaces, store clothes contaminated with poisons separately, and wash them before use. Pay attention to personal hygiene.
Third, first aid measures
Skin contact: Rinse thoroughly with soap and water. Seek medical attention.
Eye contact: Open eyelids and rinse with running water for 15 minutes. Seek medical attention.
Inhalation: Remove from the site to fresh air. Seek medical attention.
Ingestion: Inadvertently, drink the appropriate amount of warm water and induce vomiting. Seek medical attention.
Extinguishing methods: anti-solvent foam, carbon dioxide, dry powder.
The Controversy Triggered by DDT
As the world’s first synthetic organic pesticide, DDT has many advantages and disadvantages. For example, DDT has a wide spectrum of insecticides, simple production, low price, strong and lasting effect, and is difficult to degrade and bioenrich.
It can migrate long distances and has many hazards to the reproductive system, nervous system and endocrine system of wild animals, especially birds and fish. Although some controversies have been conclusive, there are still many controversies. DDT Full Form
There are currently three more controversial questions: 1 about the impact of DDT on human health; 2 disabling or using DDT; 3 how to treat DDT.
The impact of DDT on human health
Although the evidence for DDT affecting wildlife is conclusive, evidence of DDT harm to human health is not sufficient. DDTs enter the main passage of the human body: ordinary people pass food, occupational exposure is through inhalation and dermal contact, and fetuses and babies can pass through the placenta and breast milk.
DDT and DDE are easily dissolved in lipids, their concentration in human adipose tissue (about 65% fat) is higher than in breast milk (2.5% ~ 4% fat), and the concentration in breast milk is higher than Concentration in blood or semen (1% fat).
The average DDT concentration in body fat of 40 DDT sprayers in Mexico is 104.48 mg/kg, however, DDT appears to be safe for humans. DDT has been used for more than 60 years but is rarely acutely toxic, even at doses up to 285 mg/kg, which only causes vomiting and does not kill.
The World Health Organization (WHO) and the American Medical Association believe that the carcinogenicity of DDT is still lacking sufficient evidence for further study.
The US Environmental Protection Agency (EPA) also believes that DDT is not sufficient for human carcinogenicity, but evidence of carcinogenicity in animals is sufficient; DDE is controversial for human carcinogenicity, but evidence of carcinogenicity in animals It is sufficient; evidence of DDD’s carcinogenicity has not been found, but evidence of carcinogenicity in animals is sufficient .
Although many studies have shown that DDT may affect human neurobehavioral, reproductive health, cancer, infant development, immunity and DNA damage, there are many conclusions. The evidence of DDT’s impact on human health needs further research.
Scholar Snedeker believes that although some early studies have shown a significant positive association between breast cancer risk and DDTs in fat or blood, most recent cases (control studies) do not support this association.
Although DDT is banned primarily from an ecological point of view rather than toxicity to humans, subsequent studies have shown that DDT may have a detrimental effect on the human body, especially infants and young children.
Scholar Beard believes that although DDT exposure may have potential links to many diseases, the evidence is not too full, mainly because methodological problems lead to unreliable results in many studies.
Snedeker also believes that many differences in analytical methods, control populations, and food factors lead to poor reliability of the results. This also shows that the DDT threat to human health will continue, and it is likely to continue until 2020.
In general, there is still much controversy about the evidence that DDT is harmful to human health, but because DDT has four properties of persistent organic pollutants (persistence, bioaccumulation, jumping, and toxicity), and historical usage is up to More than 2 million tons, although it has been ubiquitous on the earth for more than 40 years, it can still be enriched in the human body through the food chain, so DDT has potential threats to human health that cannot be ignored.
Disable or use DDT
This issue was heatedly debated before 1970, and although DDT was banned, many countries still use DDT outside of agriculture.
For example, although DDT was banned in China in 1982, it was still used for emergency vector control, dicofol production, and antifouling production until it was completely banned in 2009, but it still retained the possibility of disease prevention in emergencies.
The Stockholm Convention is working to eliminate DDT on Earth, but due to resistance to pyrethroid insecticides in alternatives, South Africa erupted several malaria epidemics after the ban on DDT in the late 20th century, forcing South Africa to re-use it in 2000.
DDT to fight malaria. Similar to this situation are some African countries such as Zambia and Zimbabwe. DDT Full Form
On the one hand, environmentalists demand a total ban on DDT; on the other hand, disease control scientists advocate the use of DDT. The controversy over whether or not to use DDT has gradually heated up.
In particular, on September 15, 2006, the WHO re-recommended the widespread use of DDT to combat malaria after more than 30 years of ban on DDT. This incident has even ignited this debate. The Stockholm meeting has a plan to phase out DDT in 2020.
However, this plan may not be successful. There are four main reasons for DDT being lifted: 1 In the face of death, it is better to pollute.
More than 500 million people are infected with malaria every year, and more than 1 million people die. Of these, 3,000 children and babies die every day from malaria. Choose the possible damage from the identified deaths and possible injuries; 2DDT fight malaria it is good.
The key factor in DDT’s fight against malaria is not an insecticide, but as a repellent that can drive mosquitoes out of the room to prevent the spread of malaria.
At the same time, mosquito resistance to DDT is usually not strong; 3DDT substitutes are powerless. There are many substitutes for DDT, but it is more expensive and difficult for African people to accept, or the effect is not long-lasting, or the mosquito is easily resistant.
In short, there are no drugs and measures that can really replace DDT. Changes in the way can prevent DDT from harming wildlife and humans as much as possible.
This is also a point highlighted by the WHO: using the DDT for proper indoor and outdoor spraying in the right way will not harm wild animals and humans.
In general, these are based on WHO’s attitude toward DDT: never give up on efforts to use DDT where DDT is needed.
The success of the 2020 phase-out plan for DDT is key to the effectiveness of alternatives or alternatives to control malaria. The malaria problem is very complicated.
To eliminate it very difficult, there have been several times in history that malaria has been repeated because of the ban on DDT and resistance to specific drugs.
WHO position statement: The history of malaria outbreaks after banned in countries such as South Africa suggests that there is a risk of disabling DDT before there is a suitable alternative?
Therefore, a series of measures have been taken, such as demonstration projects in Mexico and Central America, which have achieved good results.
Even if a good alternative or solution is obtained, it will take a while to test how effective it is. For example, some drugs may develop resistance during a period of time, and the resistance may be different in different regions.
For example, DDT has not found DDT resistance in South Africa for more than 60 years, while Nigeria has found mosquitoes resistant to DDT for a year and a half. With only nine years left to find alternatives and solutions, and to test the reliability of alternatives and solutions, the likelihood of a successful DDT plan to 2020 is not optimistic.
How to evaluate DDT
Although DDT fell from the “Altar” after 1962, it was increasingly accused and denounced, and was regarded as a sinful demon, but today many people still regard DDT as a life-saving Good medicine.
In the history of pesticides, DDT is the first widely synthesized and highly effective organic insecticide. In 1939, Swiss chemist Muller first discovered that DDT can be used as an insecticide, marking the history of the use of natural and inorganic drugs to control agricultural pests for more than 2,000 years.
Organic pesticides, led by DDT, are an indispensable means of increasing food production, and the annual loss is about one-third of the world’s total food.
Secondly, DDT has effectively killed mosquitoes, flies, cockroaches, cockroaches and other pests on the battlefields of World War II curbed the pandemic of cholera, rash, and typhoid in Europe, and then successfully controlled malaria and encephalitis worldwide. Spread and save the lives of hundreds of millions of people. DDT Full Form
Third, DDT indirectly unveiled the prelude of the modern environmental movement. The Silent Spring, published in 1962, describes the environmental hazards of pesticides led by DDT.
Carson’s great work of life not only prompted the United States to soon set up an agricultural environmental organization and established the US Environmental Protection Agency (EPA) in 1970 but also promoted the world’s attention to environmental pollution. The dangers of DDT are a wake-up call for the human environment and health.
Fourth, DDT has been in use for more than 70 years and has caused serious damage to the ecosystem. DDT is ubiquitous on Earth and will continue to exist for a long time. It is one of the “most famous” pollutants in history.
In addition to being a representative of organochlorine pesticides, DDT has also been included in the list of persistent organic pollutants (POPs), lists of endocrine disruptors, and lists of persistent bioaccumulative and toxic (PBTs). Countries have priority in controlling the list of pollutants.
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The fifth and most deadly DDT, which is hailed by the people of the world as “universal insecticide”, convinces humans that they can change and transform the earth as they wish, greatly promoting the accelerated expansion of human desires and making humans more and more greedy.
Get it from nature. DDT’s great success in agriculture and health has set off a global upsurge in the development of organic synthetic pesticides and other synthetic chemicals. Since then, synthetic chemicals on the planet have increased rapidly, including many toxic and unknown toxic compounds.