COLEGIO DE MUNTINLUPA
Department of General engineering
SN, GN, M.I.
Tabusao, Francis Ivan D.
2nd Semester S.Y. 2021-2022
Date
March 1, 2022
CpE2 - GEC Elective - Learning Task 1
Score
Learning Task 1 - Case Study: DDT - Curse or Blessing?
Direction: Read the case study carefully. Write an essay discussing whether DDT is a curse or a
blessing. Do not plagiarize.
Use Calibri font, size 11, single spacing. Submit your Learning Task on Blackboard. Use the filename
format: GECE 2203-1_LT1_SURNAME Example: GECE 2203-1_LT1_TOLENTINO
Case Study
The general public first became acutely aware of the impact of human activity on ecology, the
study of the interrelationships between plants and animals that live in a particular physical
environment, through the book The Silent Spring. Rachel Carson, a marine biologist who worked
for the US Fish and Wildlife Service, wrote The Silent Spring to document the effects of DDT on
ecosystems, short for ecological systems.
DDT (Dichlorodiphenyl Trichloroethane) was first used as a pesticide by the allied troops
during World War II to eradicate typhus- and malaria-causing insects in the South Pacific islands.
Unlike many pesticides that are effective at controlling a few species of insects, DDT was the
"miracle compound" because it was able exterminate hundreds of different species of insects. After
World War II, its use continued on farms to control agricultural pests, in communities to control
mosquitoes, and in the tropics to control malaria and yellow fever.
Rachel Carson became aware of the effects of DDT in 1958 when a friend wrote to her about
the massive bird kills that resulted on Cape Cod after the land had been sprayed with DDT. For four
years she investigated the effects of DDT and discovered that significant reductions in the
populations of large birds of prey such as the osprey, peregrine falcon, and bald eagle, had occurred.
Carson wrote "DDT and other pesticides had a irrevocably harmed birds and animals and had
contaminated the entire world food supply (Natural Resources, Defense Council, 1997)."
In the years after the book was published, extensive research on the ecological effect of DDT
was accomplished. It was discovered that reductions in bird populations were the result of a failure
of the birds to reproduce. DDT degrades into another chemical (DDE), which affects the
reproductive hormones the thinning of the eggshells. Bats, aquatic invertebrates, and most fish
were found to be especially sensitive to DDT. While terrestrial invertebrates are generally not killed
by DDT, the chemical accumulates in their tissues.
Given the effects of DDT on individual organisms, one can easily envision that effects of DDT
on an ecosystem would significant. As animals eat the terrestrial invertebrates that have
accumulated DDT in their tissues, the chemicals are passed up the food chain. As the numbers of
bats, eagles, and falcons decrease, the numbers of their prey, namely insects and rodents, increase.
As the small fish which were found to be especially sensitive to DDT, succumb to its effects, the
food supply for larger fish and fish-eating mammals and birds also diminishes, resulting in declines
in their populations. By the late 1960s the effects of DDT became well known and in 1970, DDT was
banned in Sweden. In 1972, DDT was banned in the United States. In the years since, it is clear that
the ecosystems are slowly recovering. For example, in 1963, no bald eagles nested within the state
of Illinois (Rubin, 1997). In 1996, there were 20 breeding pairs. The peregrine falcon was considered
extinct in New York in 1970s. In 1996, there were 32 breeding pairs. Unfortunately, the ban of DDT
is not without some detrimental effects. During the 1960s, when DDT use was at its greatest, the
number of cases of malaria in Sri Lanka was essentially zero. In Sri Lanka, house spraying of DDT
ceased in 1961. In 1968, a major epidemic of malaria occurred. The cessation of house spraying of
DDT in Brazil, Ecuador, Peru, Colombia, and Venezuela resulted in more than 12 million cases of
malaria between 1980 and 1988 (Attaran et al., 2000). Since the banning of DDT, malaria epidemics
have occurred in Swaziland (1984) and Madagascar (1986-88), where malaria killed more than 100
thousand people (Roberts, Manguin, and Mouchet, 2000).
Essay:
DDT a pesticide or a biocide DDT or Dichlorodiphenyl Trichloroethane was used in the early 40’s as
a control to insect vectors in World War II and then it transitioned to be used as a pesticide. DDT
brought a positive outcome in fighting Malaria and yellow fever as it terminates mosquitos and
other insects carrying diseases however, it does not also eliminate mosquitos but also feathered
animals like birds are also affected. DDT affecting the bird’s population also affects the food chain,
yes it kills insects that cause diseases, but it also kills other organism and especially birds that eats
insects too. If birds’ population has gone down the food chain will be affected leaving more pests
in the surroundings because the predator has gone down. Who would benefit more? Will we
consider DDT a pesticide that will stop Malaria or a biocide that exterminates other living things?
Rubric: