Dichlorodiphenyltrichloroethane, or DDT, is an organochloride that is a colourless, flavourless, and nearly odourless crystalline chemical substance. It was initially created as an insecticide, but its effects on the environment made it notorious. Toxic pesticides such as BHC, PCB, DDT, and others are not easily degraded and have a long life in the environment. As a result, their concentration in water and soil increases with each application. For many years, DDT was sprayed on marshes to control mosquitoes. During the second half of World War II, DDT was employed to prevent the spread of the insect-borne diseases typhus and malaria among both civilians and military personnel. This article will explain to you about DDT which will be helpful in preparing the Environment Syllabus for the UPSC Civil Service exam.

DDT - Properties

• Dichlorodiphenyltrichloroethane is a chemical compound with the formula C14H9Cl5.
• This chemical compound has a molar mass of 354.48 grammes per mole.
• This substance has a density of about 1 gramme per cubic centimetre under normal circumstances.
• This chemical compound's melting point is roughly equivalent to 108.5 degrees Celsius (or 381.6 Kelvin).
• This chemical compound's boiling point is around 260 degrees Celsius (or 533 Kelvin). However, it's crucial to remember that when heated to these temperatures, DDT decomposes.
• DDT dissolves relatively poorly in water. Practically speaking, this substance is insoluble in water.
• Dichlorodiphenyltrichloroethane dissolves in water at a rate of 25 micrograms per litre (at a temperature of 25 degrees Celsius).

DDT - Uses

• DDT can be obtained in a variety of forms, such as xylene or petroleum distillate solutions, emulsifiable concentrates, water-wettable powders, granules, aerosols, smoke candles, vaporizers and lotion charges.
• Between 1950 and 1980, DDT was extensively utilised in agriculture, with more than 40,000 tonnes generated annually and 1.8 million tonnes produced globally since the 1940s.

DDT as a Pesticide

• By activating sodium ion channels in neurons and allowing them to fire spontaneously, DDT causes spasms and death in insects.
• Insects with some sodium channel gene mutations are resistant to DDT and its relatives.
• In some insect species, the genes encoding the cytochrome P450 are upregulated, which speeds up the breakdown of the toxin into inactive metabolites and confers DDT tolerance.
• Based on genomic studies, Drosophila melanogaster, a model genetic organism, has polygenic DDT resistance.

DDT as a Persistent Organic Pollutant (POP)

• DDT is one of the 12 Persistent Organic Pollutants which was taken into consideration under the Stockholm Convention.
• POPs are hazardous substances made up of organic (carbon-based) chemical compounds and combinations.
• They are primarily wastes produced as a result of industrial processes, chemical manufacture, and related goods and byproducts.
• POPs have only been around for a short time since the post-World War II industrial output surge.

*To know more about the topic, click this link Stockholm Convention on POPs

How People are Exposed to DDT?

• DDT is most commonly ingested through foods such as meat, fish, and dairy products.
• DDT can be absorbed through eating, breathing, or touching DDT-contaminated products.
• DDT is broken down in the body into several breakdown products known as metabolites, one of which is dichlorodiphenyldichloroethene (DDE).
• DDT and DDE are stored in the fatty tissues of the body.
• DDT and DDE can be passed to the foetus in pregnant women. Both chemicals are found in breast milk, exposing nursing infants to them.

DDT - Negative Effects

• Endocrine Disruptor: DDT is a well known endocrine disruptor. As a result, the endocrine system may be affected due to exposure to this substance.
• Carcinogen: Additionally, this substance may cause cancer in people. It should be mentioned, nonetheless, that numerous research point to the fact that this substance is not genotoxic.
• Moderately Hazardous: It should be noted that DDT is listed by the US NTP as a moderately hazardous toxin. It is estimated that this chemical compound is safe for people to be exposed to indirectly.
• Affects Thyroid Function: DDT is also known to impact pregnant women's thyroid function normally.
• Autism in Children: This substance has been connected to an increased chance of autism in children.
• A Persistent Organic Pollutant: DDT is categorised as a persistent organic pollutant. This substance has the ability to linger in the soil for up to 30 years.
• Thinning of Eggshell: Numerous North American and European bird of prey species have experienced population losses and eggshell thinning as a result of DDT bioaccumulation. DDT disrupts egg shell formation by causing a breakdown in steroid hormones, resulting in fragile eggs that break before the young hatch.
• DDT has been shown to inhibit the activity of both oestrogen, the female sex hormone, and testosterone, the male sex hormone.
• Fish die from eating DDT-killed insects, turtles from eating DDT-killed fish, and so on. DDT deposited in milk butter fat poses a risk to infants.
• As a result of DDT use, entire populations of predatory birds such as the fiddler crab and detritus feeders such as the fiddler crab are wiped out.

Thinning of Eggshell due to DDT

DDT - Bioaccumulation and Biomagnification

Bioaccumulation

• DDT tends to build up in the fatty tissues of insects, animals, and humans but does not appear to have any harmful effects while it is doing so.
• In the body, DDT is metabolised into a number of breakdown products, including DDE, DDD4, and DDA5.
• The breakdown products of DDT are released into the blood when fat stores are used up during times of hunger, where they may be hazardous to the liver and neurological system.
• DDT is eliminated from the body through the urine, faeces, or breast milk once it has accumulated in the body.
• It is frequently used to gauge a population's DDT exposure through breast milk.

Bioaccumulation of DDT

Biomagnification

• DDT has bio-magnified from the environment to fish-eating birds and humans.
• DDT tends to accumulate in animals because of its chemical makeup.
• DDT accumulates in the fatty tissues of predators as lower-level animals are consumed by creatures higher up the food chain.
• This process of accumulation across the food chain is called biomagnification.
• The process continues until the top predator in the food chain takes the largest dose, which could have a negative impact on their health.

Biomagnification of DDT

Conclusion

It's important to maintain rationality when discussing such matters because any instinctual evaluation of the environmental issues that DDT caused must be balanced by consideration of the immense benefits that it brought to humanity and the millions of lives that it helped save during the malaria eradication campaigns of the 1950s and 1960s. DDT has, overall, greatly benefited the globe, but it nevertheless serves as a potent warning that any chemical that is widely introduced into the environment should be investigated for any potential side effects that might occur. However, the chemical is still used in some regions, especially as an indoor mosquito insecticide in regions where malaria is still a serious public health concern.