By
Travis Slaysman
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DDT or dichlorodiphenyltrichloroethane is part
of the organochlorine insecticide family.
It’s a crystalline solid at room temperature and
its tasteless and almost odorless.
Chemical Formula: C14H9Cl5
Molar Mass: 354.49 g/mol
Melting Point: 108.5 ⁰ C
Boiling Point: 260 ⁰ C
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DDT was first synthesized in 1874 by German
chemists. At this time no one realized any
advantages of the compound.
In 1939, a Swiss chemist by the name of Paul
Hermann Müller discovered that DDT was an
extremely effective at killing insects, in
particular, mosquitoes.
DDT was used commonly in World War II to
help control the spread of malaria and typhus.
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Paul Hermann Müller
was awarded the
Nobel Prize in
Physiology or
Medicine in 1948 "for
his discovery of the
high efficiency of
DDT as a contact
poison against several
arthropods.”
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After World War II, DDT was made
commercially available as an insecticide which
subsequently led to widespread production and
use of the insecticide.
In 1962, an American Biologist by the name
Rachel Carson wrote a book, Silent Spring, which
catalogued the detrimental environmental
impacts by unregulated and unquestioned
spraying of DDT in the United States.
As use soared the impact DDT has on the
environment began to become more noticeable.
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DDT became the most common pesticide used
on crops in the United States in a very short
period of time.
From 1950 -1980 it is estimated that 1.8 million
tons of DDT was produced.
The average usage of DDT until its ban in 1972
was approximately 600,000 tons/year.
DDT is still being produced internationally. In
2009, 3314 tons of DDT was produced.
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DDT was studied intensely while its use was
still prevalent from approximately 1940 – 1975,
studies since then have declined due to its ban.
During the 1950’s, DDT use began to decline
due to research that was coming out on the
possible toxic properties of DDT and its
metabolites, DDE
(dichlorodiphenyldichloroethylene) and DDD
(dichlorodiphenyldichloroethane).
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DDT and its metabolites have been studied for
possible toxic effects in both humans and the
wildlife population.
Research discovered a multitude of serious
impacts on different species, with the bird
population seeming to be the most effected.
Many believe DDT to be one of the main
reasons that particular bird populations
dwindled to the point they became an
endangered species.
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DDT has been classified as acutely toxic to
birds.
Research has shown that DDE, a metabolite of
DDT has been shown to cause thinning of
bird’s eggshells.
DDT is toxic to birds at doses of approximately
400 mg/kg, but doses as low as 10-15 mg/kg
show a decline in their fertility as well as fewer
hatchlings per clutch.
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DDT is highly acutely toxic to aquatic life as
well as amphibians.
Fish are not able to detect DDT in their
environment, making them more susceptible to
ingesting it.
When ingested by fish, DDT disrupts
membrane function and enzyme activity.
DDT has a half life range of 2 – 16 years in a
soil environment.
Its half life in aquatic environments is 150
years.
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Predatory birds are the most susceptible to
DDT because of their diet. The fish they
consume contain DDT which builds up in their
system as it can’t be metabolized.
Bioaccumulation, which is the increased
concentration of a toxin as it moves up the food
chain, is one of the biggest concerns left from
DDT usage.
DDT’s persistence in the environment made it
an ideal choice as an insecticide, but it’s also
the reason why it is still a concern.
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DDT is soluble in lipids and oils, causing it to be
stored in the fatty tissue of humans. When fat is
broken down, usually during periods of starvation,
DDT is released into the blood stream where its
toxic to the liver and nervous system.
Humans are usually becomes present in the body
due to ingestion rather than inhalation or
absorption through skin contact.
DDT is classified as a B2 carcinogen, meaning it’s
been shown to cause cancer is lab animals, but not
in humans.
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DDT is an extremely potent poison to
mosquitoes, which carry a multitude of
diseases.
From 1946 to 1950, reported cases of malaria
dropped from 400,000 to almost zero.
Although DDT was banned in the United
States in 1972, DDT is still used where there is a
great risk of malaria and other disease carried
by mosquitoes.
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When the book Silent Spring was released, it is
believed to start what many refer to as the
modern environmental movement.
A year after the book was released, John F.
Kennedy formed a committee in order to
investigate the claims made in the book. The
committee had come to the conclusion that
Rachel Carson’s thesis was accurate, and that
persistent toxic pesticides should be phased out
as soon as possible.
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In 1967, a group of lawyers and scientists
paired up and founded the Environmental
Defense Fund and began a push for a ban on
the use of DDT.
The EDF subsequently filed a law suit looking
to specifically ban DDT. In 1971 the United
States Court of Appeals requested the EPA
begin the de-registration of the pesticide, and
in 1972, the ban on DDT use in the United
States became official.
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After the United States banned DDT, other
European countries followed suit.
DDT’s worldwide use was further restricted by
the Stockholm Convention in 2004, which has
been ratified by over 170 countries.
Use of DDT is only permitted for ‘vector
control’ which means that its use is only for the
elimination and control of disease spreading
insects.
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Many African, South American and Asian
countries still spray DDT to this day in order to
control spread of disease. It is sprayed in
controlled manners in relatively confined
spaces, usually in homes.
India and North Korea both still use DDT as
means of an agricultural pesticide.
Currently, approximately 3000 – 4000 tons are
produced annually.
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U.S. EPA: DDT – A Brief History and Status.
http://www.epa.gov/opp00001/factsheets/chemi
cals/ddt-brief-history-status.htm (accessed March
28, 2013)
NPIC: DDT Technical Fact Sheet
http://npic.orst.edu/factsheets/ddtgen.pdf
(accessed March 28, 2013)
NPIC: DDT General Fact Sheet.
http://npic.orst.edu/factsheets/ddttech.pdf
(accessed March 29, 2013)
DDT.http://en.wikipedia.org/wiki/DDT#Effects_
on_wildlife_and_eggshell_thinning (accessed
March 29, 2013)