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DDT Persists in Penguins Despite Decades-Old Ban
May 07, 2008 08:00 AM
by
findingDulcinea Staff
by Lindsey Chapman
The levels of DDT in Antarctic Adélie penguins have remained constant despite the fact the pesticide was banned in the Northern Hemisphere in the 1970s.
The levels of DDT in Antarctic Adélie penguins have remained constant despite the fact the pesticide was banned in the Northern Hemisphere in the 1970s.
30-Second Summary
DDT was developed in the 1940s to kill mosquitoes and prevent insect-borne diseases such as malaria. It’s also been used for insect control on crops.
In 1973, the United States banned DDT because of the variety of risks it posed to human and environmental health. Other countries have similar bans, although a few still use the pesticide to help control disease.
The DDT bans have helped the environment. In the Arctic, DDT levels have steadily declined. However, in the Antarctic the levels of the chemical appear to be much the same as when it was banned. The area’s Adélie penguins also have the chemical in their systems.
Researchers measured DDT levels in 12 dead penguins and 27 ruined penguin eggs. The chemical measured at levels similar to those detected in the 1960s and 1970s. However, because the sampling of penguins wasn’t very sizeable, the results are inconclusive.
Although DDT was never used in Antarctica, it traveled there through the atmosphere and was deposited in ice, snow and ocean water. Scientists blame the continued presence of DDT on the melting of glacial ice.
After the chemical enters the water, it is consumed by various organisms, moving up the food chain until it is ingested by penguins.
The quantities of DDT in the penguins aren’t large enough to harm the birds, but its continued presence shows just how long the chemical stays in the environment, says Heidi Geisz, a researcher who helped with the penguin study.
In 1973, the United States banned DDT because of the variety of risks it posed to human and environmental health. Other countries have similar bans, although a few still use the pesticide to help control disease.
The DDT bans have helped the environment. In the Arctic, DDT levels have steadily declined. However, in the Antarctic the levels of the chemical appear to be much the same as when it was banned. The area’s Adélie penguins also have the chemical in their systems.
Researchers measured DDT levels in 12 dead penguins and 27 ruined penguin eggs. The chemical measured at levels similar to those detected in the 1960s and 1970s. However, because the sampling of penguins wasn’t very sizeable, the results are inconclusive.
Although DDT was never used in Antarctica, it traveled there through the atmosphere and was deposited in ice, snow and ocean water. Scientists blame the continued presence of DDT on the melting of glacial ice.
After the chemical enters the water, it is consumed by various organisms, moving up the food chain until it is ingested by penguins.
The quantities of DDT in the penguins aren’t large enough to harm the birds, but its continued presence shows just how long the chemical stays in the environment, says Heidi Geisz, a researcher who helped with the penguin study.
Headline Links: DDT in the Antarctic
Glacial melting could be causing the steady levels of DDT in the Antarctic, but Discovery News notes that melting is also taking place in the Arctic, where overall levels are dropping. Researcher Heidi Geisz suggests that the Arctic is probably experiencing a similar phenomenon through the melting, but because the amount of DDT already in the ecosystem is dropping, the DDT released might not be as apparent.
Source: Discovery News
Although other pesticides that were never used in Antarctica also remain present on the continent, researchers chose to focus on the insecticide because the historical records of its presence on the continent are the most abundant.
Source: Daily Press
Historical Context: Understanding DDT’s effects
In 1945, the Fish and Wildlife Service reported that although DDT was an important tool in controlling insects, it could cause “considerable damage to wildlife, beneficial insects, and indirectly to crops.” The agency urged caution because of “our knowledge and our ignorance” of the full range of DDT’s effects.
Source: The Fish and Wildlife Service
It took three years of study before the U.S. government concluded that the use of DDT should stop. Although the Environmental Protection Agency decided to prohibit DDT in June 1972, the full ban was delayed nearly six months to ease the transition to substitute pesticides for farmers.
Source: The Environmental Protection Agency
Related Topics: Health risks of DDT
Men who are exposed to DDT and other similar pesticides over time have increased chances of developing a common form of testicular cancer, according to WebMD. This chemical exposure has also been linked to human reproductive damage.
Source: WebMD
Reference: What is DDT?
Before it was banned, DDT was a common pesticide. The United States no longer uses or produces it, but other countries apply the chemical for disease control and agricultural practices. DDT causes some concern because it not only takes more than 15 years for the substance to break down in the environment, but it also poses numerous health risks to people.
Source: The Environmental Protection Agency
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