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.There’s a lot of work that goes into identifying POPs as threats to human and environmental health. Designated committees, scientists, and other experts work hard to describe POPs, how they persist in the environment, and what effects they have. To date, 152 countries have signed the treaty, and 179 have ratified it. The difference between the two is like the difference between being engaged and being married. When countries sign the treaty, this is like a promise to commit to its rules and regulations at a later time.
Once it’s been ratified, that country is now fully committed to the treaty and must abide by its provisions. The U.S. is one such country that has signed, but not ratified the Stockholm Convention treaty.
Persistent organic pollutants, or POPs, are toxicants that remain in the environment for long periods of time. POPs may linger in water or soil, or they may accumulate in animal tissue and build up as they move up the food chain. As we saw with the alligators in Florida and the polar bears in the polar regions, POPs can have detrimental and long-lasting effects on hormone systems and other bodily functions, even far from their source of origin.
Because POPs are so dangerous, the Stockholm Convention on Persistent Organic Pollutants was convened in 2001. This international treaty identified 12 of the most dangerous POPs, set guidelines for discontinuing their use, and suggested safer alternatives. POPs don’t need a passport to travel across boundaries, and because they hang around and move so well, an international treaty seemed the best way to address them.Nicknamed the Dirty Dozen, the 12 POPs originally identified by the Stockholm Convention include pesticides, insecticides, refrigerants, and other toxic chemicals.
152 countries, including the U.S., have signed the treaty so far, indicating they plan to adopt the principles at some point. 179 countries have ratified it, meaning that they are fully committed and bound by the rules of this important international agreement.
After this lesson, you’ll be able to:
- Explain what persistent organic pollutants are and why they are so damaging to human and environmental health
- Describe the purpose and outcome of the Stockholm Convention on Persistent Organic Pollutants
- List some examples of POPs considered by the Stockholm Convention to be the ‘Dirty Dozen’
- Explain the adding mechanism as it is used in the Stockholm Convention
- Differentiate between signing a treaty and ratifying a treaty