When people hear the word, "pesticides," they often associate it with something very negative. And many times, they'll soon think of DDT.
DDT is one of the most famous pesticides in the world, and it has been with us for quite a long time.
Not many of us, though, are aware of what DDT is and how it works. This module is here to hopefully give you some insight into the science behind this fascinating chemical.
Some questions about DDT that we'll try to answer:
a) What exactly is it?
b) Why is it so dangerous?
c) Are we safe from it now?
History and Uses of DDT
Even though someone created DDT back in the 19th century, only around 1939 did Dr. Paul Muller discover that it was effective in killing insects, and shortly after, he won the nobel prize in medicine for this work.
As a pesticide, DDT was first used during WWII. It was so effective as an insect killer that some called it the "atomic bomb" of pesticides.
After WWII, we realized that DDT could also be used on farms to control some common agricultural pests.
Some of agricultural pests controlled by DDT:
various potato beetles
coddling moth (which attacks apples)
In addition to its use in farming, DDT was still used to control certain insects which carried diseases like malaria and yellow fever.
Because of all these uses for DDT, the United States used a lot of it during the mid-1900s. (At one point, the US was producing 220 million pounds of DDT a year!)
By the 1970s, we began to get worried about DDT's environmental and health effects. So finally in June of 1972, the US Environmental Protection Agency (EPA) cancelled all use of DDT on crops. (For certain cases of disease control, the EPA allowed for limited use.)
DDT usage today
While no longer used any longer in the US, DDT use continues in other parts of the world. Many tropical countries still use DDT to control malaria.
Here is a graph of the number of cases of malaria over a period of years. What does this graph tell you? What years did malaria minimize and maximize? Can you guess during which years DDT was used?
This completes our Introduction to DDT.
Return to the beginning of the Pesticides unit.