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Current Time and Temperature at Palmer Station
Current time and temperature at Palmer Station


Headline: The Project

Persistent Organic Pollutants (POPs)

To view a printable version of this page, click here.

Glossary words on this page (glossary words are shown in red):

accumulate: gather together; increase gradually

characteristics: qualities; properties

environment: surroundings; physical, chemical, and biological factors acting upon an organism or an ecological community

evaporate: change into vapor

predator: an animal who gets most of its food by killing and eating other animals

prey: an animal taken by another as food

POPs have been called "hand-me-down poisons that threaten wildlife and people" (World Wildlife Fund). The United Nations Environment Programme lists twelve of them as "The Dirty Dozen." More than one hundred of the world’s countries have been working on a treaty to ban the production and use of these chemicals. In May 2001, diplomats from around the world came to Stockholm, Sweden, to sign an agreement to limit POPs. (This agreement needs to be ratified by the governments of at least fifty countries in order to go into effect)

What are POPs?

POPs are chemicals that have been made by humans or result from human activity. There are three general categories of POPs:

  • Pesticides (DDT, chlordane, heptachlor, and five others):
    Produced to be toxic, in order to improve crop and livestock production by killing agricultural pests and to kill insects carrying diseases such as malaria and typhus
  • Industrial chemicals (PCBs and HCB):
    Designed for industrial uses, such as in electrical transformers and capacitors, in paint additives, in fireworks, ammunition, and plastics

    Not intended to be toxic, but they contain harmful elements.
  • By-products of other processes (Dioxins and Furans):
    Not produced intentionally; serve no useful purpose

    They occur by the burning of materials containing chlorine, such as PVC (vinyl) plastic, bleached paper, paint strippers. They also are made by burning municipal waste, hospital waste, hazardous waste, and by landfill fires. They can come from power plants, diesel engines, and other uses of leaded fuels.

Why are people concerned about POPs?

POPs have four main characteristics that cause worry.

  1. POPs are persistent.
    They are chemicals that remain in the environment for years. In fact, they may be present for many decades. They degrade, or break down, very slowly. Once they are produced and travel to the air, water, soil, and food supply, POPs last a long time.

  2. POPs are known to "bio-accumulate" and "bio-magnify".
    POPs have a special attraction or affinity to fats. They bind with these fats and accumulate in the fatty tissues of living organisms. They get into the food web as animals are eaten by other animals. POPs become more concentrated as they move from the bodies of smaller prey to larger predators. The top-level predators, such as whales, polar bears, and humans, can have higher levels of POPs than the animals making up the basis of the food web.

  3. POPs are global travelers.
    POPs move around the world by a process called "global transport". They appear in places where they have never been used or produced. Here’s how it works: POPs evaporate at warm temperatures. The vapor travels in air currents of the atmosphere. When the vapor cools, it settles on the land and water. This happens again and again, just like a grasshopper jumps around. In fact, "the grasshopper effect" is the name for the way POPs are able to travel so far. POPs move thousands of miles from the warmer latitudes of the Earth (where they are produced) to the cooler latitudes at the North Pole and South Pole.

  4. POPs are toxic.
    Many studies have shown that POPs can be harmful to wildlife and humans. They can be dangerous at low levels as well as at high concentrations. POPs are related to damage to the nervous system, to the liver, and to reproduction. They are connected to birth defects. They are identified as "endocrine-disrupters," which means they influence and interfere with the human body’s own hormones. There may be a connection between cancer and some POPs.

Since this POPs scientific research expedition in 2002, many things have occurred. The Stockholm Convention was “entered into force” on May 17, 2004. The text of the Stockholm Convention: http://chm.pops.int/TheConvention/Overview/tabid/3351/Default.aspx

History of the Convention

Check this map to see which countries have ratified the Stockholm Convention by using this Map of "parties to the Convention": http://chm.pops.int/Countries/StatusofRatifications/tabid/252/Default.aspx


IPEN Resources

IPEN is a global network working to establish and implement safe chemicals policies and practices that protect human health and the environment around the world.

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Diagram courtesy of Stockholm Environment Institute-York; adapted from Wania, F and D. Mackay, (1996) Tracking the distribution of persistent organic pollutants, Environ. Sci. & Technol. 30, 390-396.