January 14, 2005
What are POPs?
Real Audio Report
This is Chris Johnson speaking to you from the Odyssey.
The chemical revolution of the past fifty years has seen the development of a suite of chemicals with the primary intention of improving standards of living worldwide. Today, the contamination from persistent, man-made chemicals is a pervasive global problem that demands immediate global attention.
Dr. Celine Godard is an Environmental Toxicologist and the Voyage of the Odyssey Chief Scientist. While overseeing the interdisciplinary science program, her specific focus lies in further understanding the impact of these pollutants on whales.
Dr Godard explains.
Dr. Celine Godard:
"The acronym 'POPs' stands for persistent organic pollutants. These are a group of chemicals that are known to present a toxic threat to humans, wildlife and the environment. These chemicals are called persistent because they are resistant to degradation by the environment and by biological organisms. In other words they can endure for very long periods of time after having been produced and released into the environment. This gives them a large window of time during which they can get into contact with animals, accumulate in their tissues and get transmitted through the food chain.
POPs are man made chemicals. Some are created intentionally for agricultural or industrial purposes. Examples are insecticides such as Aldrin, Dieldrin, Myrex and Dichlorodiphenyltrichloroethane (DDT), and industrial chemicals such as polychlorinated biphenyls (PCBs) used in electrical heat transfer and hydraulic equipment.
Other POPs suggest dioxins and furans are produced unintentionally as chemical byproducts from most forms of combustion including municipal and industrial waste incinerators. While some POPs have been banned in many industrial countries, they are still in production or used in other parts of the world.
Most chemicals released into the environment end up in the oceans. It may take a few days, several weeks or years for chemicals to find their way to the oceans, depending on where they were released. It could be a direct release, such as a coastal discharge or indirect release such as a pesticide applied in agricultural fields hundreds of miles from shore and that will travel to the sea via underground water. The end result though is the same, and the oceans unfortunately are the final sink for most if not all environmental chemicals.
There are many types of POPs present in the environment, but attention has been turned mainly towards twelve of them called the dirty dozen. They include pesticides such as DDT, Aldrine and chlordane and industrial chemicals or industrial byproducts such as PCBs dioxins and furans. All these chemicals are present in the environment; therefore humans and animals are exposed to various mixtures of pollutants. Scientists are studying exactly what happens when POPs mix together. The toxic effects of such mixtures are not necessarily equal to the sum of the toxic effects of each compound present in the mixtures. In some cases, the overall toxicity is greater than the sum; this is referred to as a synergetic mixture. While in other cases, the overall toxicity can be smaller as in an antagonistic mixture.
With Odyssey science manager Cormac Booth, Dr. Celine Godard prepares a biopsy sample taken from a sperm whale in the Odyssey lab.
Photo - Chris Johnson
POPs pose a threat to humans and wildlife worldwide. They have a widespread distribution because they are transported and disseminated through atmospheric and oceanic currents all over the planet. Therefore, even if there are localized production sources in specific countries, these chemicals will circulate and be distributed worldwide. The international community recognizes POPs as a threat to environmental and human health and created a global treaty called the Stockholm Convention. This treaty came into effect in May, 2001 and signatory governments agreed to take measures to eliminate or reduce the production, use and release of POPs into the environment starting in May 2004.
POPs are known to create numerous deleterious effects in animals. Studies have shown in mammals that POPs can create cancers and damage the immune system, nervous system, reproductive system and endocrine system. Direct exposure studies are not possible in humans, but data from accidental exposure combined with animal studies strongly suggest that PCBs are probable human carcinogens as well. Interestingly a recent US EPA (Environmental Protection Agency) assessment concluded that the PCB mixtures likely to bioaccumulate in fish and other animals are the most carcinogenic. As a result, people who consume large quantities of PCB contaminated, or other POP contaminated fish, are likely to be particularly at risk.
Few studies are available on the effects of POPs in marine mammals, but because these animals are positioned at the top of marine food chains and have a long life span, they are likely targets for bioaccumulation of these chemicals. Overall, whales are likely to be susceptible to the same effects caused by POPs in terrestrial mammals because they share many physiological traits with them."
In 2000, the Ocean Alliance launched the Voyage of the Odyssey, a multi-year program designed to gather the first-ever baseline dataset on the concentration, distribution and potential
effects of synthetic contaminants throughout the world's oceans.
The whale research vessel Odyssey is in its final year circumnavigating the world collecting small biopsy samples from sperm whales.
Sperm whales - with their longevity, thick blubber, and position at the top of the oceanic food chain - reveal levels of toxicity.
Log written by Dr Celine Godard & Genevieve Johnson.