DDT (dichloro-diphenyl-trichloroethane) was developed as the first of the modern synthetic insecticides in the 1940s. It was initially used with great effect to combat malaria, typhus A group of infectious diseases caused by bacteria which spread to humans through fleas, lice and chigger bites.Typhus
Why was DDT banned as a pesticide?
Why was DDT banned? DDT, or dichlorodiphenyltrichloroethane, is a colorless and tasteless chemical compound developed as an insecticide and its use was banned because of its role in the increased risk of serious health conditions in humans and animals alike. DDT was at the height of its popularity during the second World War.
What is the truth about DDT?
While DDT is highly toxic to insects and fish and can poison other animals in large enough doses, in moderate amounts it’s not especially harmful to birds and mammals, including humans. (Ironically, the EPA’s own judge agreed, but was overruled by its chief administrator.) No one has conclusively proved that DDT can give you cancer.
What are the pro and cons to DDT use?
The widespread use of DDT began in 1945 to control agricultural pests and mosquitoes. DDT is extremely toxic to insects-both those that benefit the crops and those that destroy them. DDt is inexpensive, kills most pests, and provides lasting protection because it breaks down slowly. DDT is believed to have helped same millions of human lives.
How was DDT harmful?
DDT is toxic to a wide range of living organisms, including marine animals such as crayfish, daphnids, sea shrimp and many species of fish. DDT, DDE and DDD magnify through the food chain, with apex predators such as raptor birds concentrating more chemicals than other animals in the same environment.
See more
What insecticide is used to kill malaria?
of the insecticide DDT(1,1,1-trichloro-2,2,-bis[p-chlorophenyl]ethane, or dichlorodiphenyltrichloro-ethane). It had long been realized that the only effective way of controlling malaria was to eradicate the anopheline mosquitoes that transmit the disease. Older methods of mosquito control, however, were cumbersome and expensive. The lethal effect of DDTon the mosquito,…
What is the melting point of DDT?
Pure DDT is a colourless, crystalline solid that melts at 109° C (228° F); the commercial product, which is usually 65 to 80 percent active compound, along with related substances, is an amorphous powder that has a lower melting point. DDT is applied as a dust or by spraying its aqueous suspension.
What is the effect of DDT on insects?
Many species of insects rapidly develop populations resistant to DDT; the high stability of the compound leads to its accumulation in insects that constitute the diet of other animals, with toxic effects on them, especially certain birds and fishes.
What is an encyclopedia editor?
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. ...
When was DDT first made?
DDT, prepared by the reaction of chloral with chlorobenzene in the presence of sulfuric acid, was first made in 1874; its insecticidal properties were discovered in 1939 by a Swiss chemist, Paul Hermann Müller.
Is DDT a mothproofing agent?
DDT was far more persistent and effective than any previously known insecticide. Originally a mothproofing agent for clothes, it soon found use among the armies of World War II for…. of the insecticide DDT (1,1,1-trichloro-2,2,-bis [ p -chlorophenyl]ethane, or dichlorodiphenyltrichloro-ethane).
Does DDT kill mosquitoes?
During and after World War II, DDT was found to be effective against lice, fleas, and mosquitoes (the carriers of typhus, of plague, and of malaria and yellow fever, respectively) as well as the Colorado potato beetle, the gypsy moth, and other insects that attack valuable crops.
How does DDT affect the insect nerve?
DDT interacts with the sodium channel in the insect nerve and retards its closure. This means that the flow of sodium and hence the electric current is prolonged and there may be several impulses instead of just one. The function of the nerves thus becomes uncontrolled. This effect of DDT seems to be reversible.
Why are insects more susceptible to DDT than mammals?
It seems that insects are more susceptible than mammals, for two reasons. The first is that insect nerves are more susceptible to the DDT. The second is that mammals have a more well-developed system of detoxication than insects and so remove it more effectively. Naturally, at high doses DDT will cause toxic effects in humans, ...
How does DDT work?
How DDT works and why it is toxic to insects but not mammals. The mechanism by which DDT acts is to disturb the function of nerves in the insect. Nerves in both insects and humans work by allowing an electric current to move down them. This action potential, as it is called, depends on the movement of two metal ions, sodium and potassium, ...
Why do birds have a high sensitivity to DDE?
It is believed to be due to the effect of DDE on the disposition of calcium in the shell gland which is involved in the production of the eggshell . Other organochlorine compounds may also cause this effect but it seems that birds vary significantly in their sensitivity; the raptors and fish-eating birds being the most sensitive.
What is the effect of DDT on birds?
One such effect of DDT is to alter the production of eggs, in particular the eggshells. During the 1960s the eggs of birds such as the peregrine falcon and pelican were found to have thinner shells and were therefore liable to break, a phenomenon which had started in the i940s. This was later found to correlate with the level of DDE, ...
Why is it easy to point the finger at DDT?
It became easy to point the finger at DDT because many birds and other animals had detectable levels of the chemical. But just because a chemical is detectable in an animal does not mean that it causes either death or ill health or that the level is hazardous.
How long does it take for DDT to get out of the soil?
It is degraded only slowly in soil and in some of the animals exposed to it. It may take between five and twenty-five years for the soil to lose 95 per cent of the DDT.