Harmful Effects of DDT on the Earth

1
Harmful Effects of DDT on the Earth

• By Ligaya Madamba

2
DDT

• During World War II, Paul Hermann Müller
  discovered that the chemical, DDT, could be used
  as an insecticide.

3
What is DDT?

• A hydrophobic (repelled by water), odorless,
  colorless, crystalline solid that is not very
  soluble in water. It is created by reacting
  trichloroethanal and chlorobenzene.

4
DDT as an Insecticide

• Often referred to as the atomic bomb of
  pesticides, DDT, was used to kill malaria
  carrying mosquitoes and many more

• insects that carried typhus and other diseases.
  It was also used to kill various arthropods that
  attacked farms.

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Effects of DDT

• BENEFITS
• From 1948 to the 70s, DDT seemed to be very
  beneficial.
• DDT
• -completely destroyed malaria from Europe,
  Brazil, Egypt, and North America
• -controlled typhus carried by lice in Italy
• -controlled insects that carried yellow fever

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DDT during the Early 70s

• In a matter of ten years people started doubting
  DDT. Personal observations were made about the
  decline in bird sightings.

• In 1962, Rachel Carson wrote a novel, Silent
  Springs, which exposed the effects of DDT.
  Nothing was done until the early 70s.

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More Sightings of Harmful Effects

• -Decrease in large birds like ospreys and eagles
  (this was due to DDTs thinning effect on their
  egg shells)
• In 1972 DDT was finally banned by the US
  Environmental Protection Agency (EPA).

• -In 1965 there was a massive decline in fish at
  Yaphank Ponds after a spraying of DDT.

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Why is DDT So Harmful?

• DDT is a big concern because it is very insoluble
  in water, but fairly soluble in fats. Its
  structure makes it very difficult for it to
  breakdown in nature.

• Since DDT is hard to breakdown and is very
  insoluble in water it can stay in the environment
  and even in human bodies for decades.

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What Does DDT Affect?

• EVERYTHING!
• DDT in microorganisms (i.e. green algae) grow
  slower and carry out photosynthesis slower.
  Since these organisms are at the bottom of the
  food chain the DDT found in higher organisms is
  magnified. Invertebrates found on land are not
  deeply affected, but aquatic invertebrates are.
  Fish and birds are extremely sensitive to DDT.

10
DDT in Humans

• DDT in large amounts can cause headache,
  confusion, tremors, and nausea. It may even be
  linked to breast cancer because DDT mimics
  estrogen. There are also hypotheses that it
  decreases the sperm count in men.

11
DDT Now

• DDT is completely banned from the US. It is
  still used in countries like China, South
  America, Africa, and Malaysia.
• In most areas DDT has become completely
  unsuccessfulmosquitoes in India and other areas
  are now immune to DDT.