The Stockholm Convention on Persistent Organic Pollutants

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  • 0:07 Persistent Organic Pollutants
  • 1:45 Twelve POPs Are Identified
  • 4:07 Lesson Summary
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Lesson Transcript
Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

In this video lesson, you will learn about persistent organic pollutants and how they led to the Stockholm Convention on Persistent Organic Pollutants in 2001.

Persistent Organic Pollutants

In 1985, Dr. Louis Guillette became concerned. He was studying alligators in Lake Apopka, which is just outside of Orlando, Florida. He noticed some startling issues with the alligators, such as females not producing viable eggs, depressed levels of testosterone in baby males, and extremely high levels of estrogen in baby females.

Dr. Guillette and his team soon determined that the hormonal changes in the baby alligators were due to a pesticide spill in Lake Apopka in 1980. These pesticides turned out to be persistent organic pollutants, also known as POPs, which are toxicants that remain in the environment for long periods of time. POPs include chemicals such as PCBs and DDT. POPs can be especially dangerous when they accumulate in animal tissue because they then move up the food chain, becoming more concentrated as they go.

POPs can have lingering effects for many years and can accumulate thousands of miles from where they originated. Polar bears in remote polar regions have shown some of the highest levels of POP contaminants, despite being in areas far from where the POPs were manufactured and applied. Even as long as ten years after the pesticide spill, the alligator hatchlings in Lake Apopka were still much smaller than those in surrounding lakes that were not polluted and were still showing abnormalities in their hormonal development.

Because POPs are so dangerous to such a wide range of organisms, international action was taken in 2001. The Stockholm Convention on Persistent Organic Pollutants was created in this year and was an international treaty designed to address transboundary pollution.

Twelve POPs Are Identified

One of the key points of the Stockholm Convention was the identification of 12 POPs that had been shown to be the most dangerous. Because they are so dangerous, these were nicknamed the 'Dirty Dozen.' The goal of the treaty was to phase out the use of these chemicals, as well as encourage the use of other, safer alternatives.

While we won't get into details about each of the 12 chemicals, it is important to know where they come from and what their uses are. Many of the Dirty Dozen are or were used as residential pesticides and insecticides, such as DDT, which caused the problems in the Lake Apopka alligators. Others, such as PCBs, were used as chemical refrigerants in vehicles, and these have been banned in the U.S. since 1979. Another, Dieldrin, was used as an agricultural insecticide. Because many of these chemicals are sprayed directly onto the food that we eat, we easily take them up into our bodies. They can also get into our drinking water supply if carried away to water sources by runoff.

It's important to keep in mind that just because chemicals have been outlined in the Stockholm Convention, doesn't mean that their use has stopped. For example, the U.S. banned domestic DDT use in 1972, but continues to manufacture it and sell it to other countries that haven't banned its use. The Stockholm Convention doesn't end with the Dirty Dozen, either. These were the first major POPs identified, but there are provisions in the treaty that allow new POPs to be identified as they become known. This is called the adding mechanism because it allows new POPs to be added to the treaty as they're identified.

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