Contaminants 101



What are “Contaminants”?:

A contaminant is a substance that is found in a place where it should not be. Not all contaminants are harmful.

Some contaminants are natural, others are man made. The term "contaminant" is used to identify particular types of non-living substances that can be harmful to plants, animals and people, or to the physical environment. A small number of these non-living substances can occur naturally, but most contaminants are produced as a result of human activity.

Contaminants are often toxic in small concentrations. Contaminant concentrations are often described in units of parts per million (ppm) or parts per trillion (ppt) as shown in the figure below (reproduced then adapted from
http://www.Taiga.net/coop/synth/contaminants/contaiminants_slide0045.htm

How To Measure Contaminant Concentrations

Northern contaminants can be divided into three groups: POPs, heavy metals and radioactivity. These types of contaminants are found in the northern environment and are potentially dangerous to arctic plants and animals, as well as to humans.

Persistent Organic Pollutants (POPs)

Persistent Organic Pollutants (POPs, also called organochlorines) are highly toxic chemicals. These are the most widespread and potentially harmful group of contaminants in the north as well as in many other parts of the world. Some POPS are products manufactured for commercial use, such as the pesticides DDT, endrin and toxaphene, and also industrial chemicals such as PCBs. Other POPs are unintentional by-products like dioxins and furans. Once manufactured or developed, POPs become some of the most dangerous chemicals ever produced. The fact that they are persistent and stay in the environment for many years make them potentially very harmful to the health of northern ecosystems, including wildlife and people.

Types of POPs

In 1995, the United Nations Environment Program (UNEP) estimated that there may be 20,000 to 70,000 chemicals with the physical properties and chemical composition of POPs being produced worldwide, amounting to 400 million tons annually. POPs are found in products that have a wide range of applications for agriculture, manufacturing, industry and public health throughout the world, including pesticides, herbicides and other industrial chemicals, as well as many for use in the home.

It should be understood that chemicals now identified as POPs have been used for applications that have, in fact, brought about substantial improvements to the health and well being of people in different parts of the world. For example, DDT is used to control malaria and typhus in tropical areas. Other toxic chemicals are used to control termites and to reduce the population of disease-carrying insects and rodents.

POPs are either used as pesticides, consumed by industry, or generated unintentionally as by-products of various industrial processes. The 12 POPs recognized as requiring the most urgent action, known as the “dirty dozen,” are: aldrin, chlorodane, DDT, dieldrin, dioxins, furans, endrin, hexachlorobenzene, heptachlor, mirex, PCBs, and toxaphene. To learn more about these chemicals, go to: http://www.itk.ca/environment/contaminants-about-dirty-dozen.php

POPs are stored in fat and are persistent

A common characteristic of most synthetic organic chemicals found in the Arctic is that they break down very slowly. This persistence in the environment allows them to accumulate in animals and to pass through the food web.

Storing energy as fat is crucial for survival in cold environments, and fat is therefore important in the diets of both people and animals who live in the Arctic. Unfortunately, most persistent organic pollutants are fat-soluble so they accumulate in the fatty tissues of animals and are passed onto humans when they eat the animals.

The combined characteristics of being fat-soluble and persistent make biomagnification a major concern, as discussed below. Indeed, the highest levels of persistent contaminants are usually found in top predators. Studies of species at different levels of an Arctic marine food web show that each step can mean a several-fold increase in body burdens of organic contaminants.

Heavy Metals

Heavy metals are minerals that are naturally present in rocks and soils in all parts of the world, including the bedrock and unconsolidated material of the Arctic. The important heavy metals with respect to northern contaminants are mercury, cadmium, and lead. Cadmium and mercury are released as by-products of mining and smelting. Significant quantities of mercury are also released as a result of the erosive and chemical actions that take place in reservoirs built to store water for large hydro-electric projects.

The primary long-range transport pathway to the Arctic for heavy metals is the atmosphere. Heavy metal particles can be carried great distances when they are incorporated into water particles. They are persistent environmental contaminants because natural processes cannot break them down. Heavy metals are found as environmental contaminants in all parts of Arctic ecosystems. With prolonged exposure, metals, and especially cadmium, bioaccumulate in lichens and other plants.

When heavy metals are carried into marine or fresh water environments by rivers or runoff, they become available to organisms in the food chain. Beluga whales are major sources of mercury in regions such as Nunivik, Canada, and lake trout are a major source of mercury from fresh water fish. Unlike POPs which are usually stored in the fat of animals, most heavy metals concentrate in the organs of animals, such as the kidney or liver.

Radionuclides

Radiation can damage DNA in cells in our bodies when their charged particles come into contact with the cells. Damage to cells may be repaired, may lead to cell death, or may cause mutations in the cell that can be passed on by the dividing cell, which could cause cancer. A radionuclide (pronounced “radio-new-clyde”) is a chemical element that gives off radiation.

Contamination resulting from the presence of radionuclides is an ongoing concern in the North. Many types of radionuclides have been found throughout the Arctic, including cesium 137 and 134, and plutonium 238, 239 and 240. Although there are natural (geological) sources of radionuclides, most radioactive contamination results from human activity.

Activities that release radionuclides into the environment include the burn- up of nuclear-powered satellites upon reentry into the atmosphere, the discharges from operating nuclear power plants, the disposal and reprocessing of nuclear waste, uranium mining, and nuclear accidents such as the Chernobyl disaster. Until restricted by international treaties in the late 1960s, atmospheric weapons testing represented a potential threat to Arctic ecosystems. At that time plans were also made to use atomic explosives to create canals and waterways in northern Alaska. Luckily, these plans were never put into effect.

Radionuclides from various sources reach the Arctic by the same pathways as POPs: winds, ocean currents and north-flowing rivers (discussed below). Radionuclides, especially strontium 90 and cesium 137 are known to be carcinogenic, are persistent, and concentrate in food chains. Radionuclides tend to be stored in bone and muscle, and not the fat, unlike other contaminants such as POPs. Scientists have done a number of studies looking at radionuclides in caribou in Canada and Alaska, and the levels are very low. In fact, a study by O’Hara et al. (1999) of Alaskan caribou found that a person would have to eat more than 85 pounds of caribou meat per day every day for a year to reach the maximum permissible intake for cesium 137! So, while it is good to be aware of radionuclides and what they can do, don’t stop eating subsistence foods because of them.

Primary resources used:
Inuit Tapiirit Kanatami http://www.itk.ca/environment/contaminants-about.php
O’Hara, T., D. Dasher, J. George, and V. Woshner, 1999. Radionuclide Levels in Caribou of Northern
Alaska in 1995-96. Arctic 53: 279-288. http://pubs.aina.ucalgary.ca/arctic/Arctic52-3-279.pdf
Wikipedia Online Encyclopedia: http://en.wikipedia.org/wiki/Ionizing_radiation


Sources of Arctic Contaminants

Research findings give clear evidence that almost all contaminants originate outside the Arctic region. They are brought to the North by strong winds, ocean currents and rivers and once here, they can build up in the Arctic environment and food chain. Parts of Asia, Europe and North America are the main sources regions for many of these contaminants.

However not all contaminants found in the arctic come from faraway sources and not all are caused by human activity. Some contaminants are natural parts of the Arctic and have been here for thousands of years without causing any problems. Mercury and cadmium can be found in very old rocks and soils of the eastern and western Arctic. There are also local sources including, landfills, dew line stations, fuel drums, sewage lagoons, and incinerators (see discussion below).

Local Sources of Contaminants

Most contaminants in the Arctic (such as pesticides, PCBs, dioxins, mercury) come from far away, from activities such as agriculture, mining, forestry, and paper-making. However, local contaminant sources also contribute to the total amount of contaminants in the Arctic. Local dump burning releases a lot of harmful contaminants into the air, and throwing away garbage such as lead paints, household cleaning fluids, batteries, motor oil, gasoline, antifreeze and plastic are all dangerous to our human and environmental health, especially if they are not discarded in the right way.

Other arctic contaminants potentially come from Abandoned Distant Early Warning (DEW) Line sites. The DEW Line sites were built beginning in the 1950's as part of the North American defense against surprise air or missile attacks from the former USSR. These radar sites were utilized for almost 30 years, and their operation required electronic equipment and support installations that contained, on a local scale, sizable amounts of PCBs. These sites contribute only 1% of the total PCBs found in the north, but the level of contamination still requires attention. These sites are now being cleaned up in Alaska and Canada.

Long-Range Sources of Contaminants

Many contaminants of concern that are found in the North have never been used in the Arctic or have been restricted for decades. So how do the contaminants travel so far?

These contaminants travel up to the Arctic on wind, ocean currents, and rivers, and once here they build up in the Arctic food chain. Of these pathways (see figures), air currents are the most important. Many POPs are semi-volatile and insoluble toxic chemicals. Their chemical and physical natures allow them to travel great distances through the atmosphere as vapor, or by attaching to atmospheric particles such as dust. Transport from chemical sources areas (see figure) to the Arctic can occur in a matter of days or weeks. For example, it takes 13-16 days for contaminants to travel from Europe to Alaska during the winter.

The “Grasshopper Effect”

Scientists have determined that some chemicals make their journey north in a step-wise fashion, evaporating at their point of release (in warmer climates), traveling north on air currents, condensing and re-depositing on soil or in water. This cycle repeats itself over and over again in a process known as the Grasshopper Effect (see figure). Eventually they reach the colder air of the Arctic and here is where they remain. This is also called "the Arctic cold trap" or the "Arctic sink hole". In fact, we now know that six tons of PCBs (originating from outside Canada) are deposited in the Canadian Arctic annually. Contaminants then build up in the food chain, exposing top predators like polar bears and humans to levels of POPs and other contaminants that are much higher than those typically found elsewhere.

The Grasshopper Effect is similar to the way mist might travel across a room. To better picture this effect, try this experiment:

When POPs reach the Arctic, the cold temperatures prevent them from evaporating back into the atmosphere. This is known as the “cold effect.” Until the POPs are broken down into non-toxic states, they can be absorbed into land and marine food chains, where biological processes take over. Due to the cold effect, POPs become essentially "locked into" the Arctic environment, despite the fact that their sources are outside of the Arctic. Reduction of POPs contamination in the Arctic, therefore, can be achieved only through action on a global scale.

Wind Transportation of Contaminants

Wind Currents like these are able to bring harmful chemicals to the Arctic sometimes in just a matter of weeks after their release.

River Transportation of Contaminants

This illustration show the flow of rivers which end up in the Arctic ocean. This is especially true of Russian rivers which may still carry large deposits of PCBs and other contaminants.

Primary resource used: Inuit Tapiirit Kanatami http://www.itk.ca/environment/contaminants- sources-pathways.php

Accumulation of Contaminants in Ecosystems

Most scientists agree that the amounts of contaminants reaching the arctic through long range transport (described above) are too small to cause detectable harm to most plants and animals. However, when plants and animal anywhere in the world are exposed to very large amounts of contaminants, the effects can be very serious. This can be seen with examples from other parts of the world. For example, the Mohawk on the Akwesasne reserve on the St. Lawrence River in southern Ontario cannot hunt or fish on their lands because the wildlife is so contaminated by industrial pollution from upstream.

How does a contaminant get into the wildlife? When it snows or rains the chemicals or metals that in the atmosphere are deposited into the water and soil and are taken up (unexpectedly) by plants, fish and other animals. Once in the Arctic marine and fresh waters, and on the land, contaminants are able to enter food chains. Contaminants are usually ingested and they accumulate over time in the bodies of the wildlife that we depend upon for food.

Contaminant levels in wildlife are largely related to the animals feeding habits. Animals high up on the food chain usually have higher levels of contaminants within their systems. For instance, a polar bear is the top predator for the maritime environment, and therefore levels of certain contaminants may be higher in polar bears than in animals lower in the food chain. Species that are dependant on plants like caribou and muskoxen have much lower levels of contamination. Other important factors include age, amount of fatty tissues, reproduction, and migration to/through contaminated areas outside of the Arctic will all influence the amount of contaminants in wildlife. A good general rule is that the younger the animal, the less contaminants it will have in its body.

Biomagnification and Bioaccumulation

“Biomagnification” refers to the increase in concentration of a contaminant at higher levels of a food chain. This means that the higher up on the food chain you are, the more contaminants you are likely to have stored in your body. If a polar bear could survive by just eating ice, the amount of contaminants in its body would be similar to a caribou eating lichen. But since bears eat seals, and those seals eat fish and those fish eat shrimp, and those shrimp eat plankton, the contaminants increase with each species eaten.

Biomagnification begins when 'persistent' contaminants - those that do not break down or decompose quickly - are consumed by organisms at lower levels on the food chain, such as algae. These organisms process and concentrate inorganic (nonliving) nutrients from their environment. In addition, most of the animals from the marine environment like seals, whales and walruses have a large supply of fat where many contaminants are stored. When an animal eats an organism, the organisms’ fat is digested and any contaminants present move to the fat of the consumer. Animals in higher levels of the food chain must consume large quantities from the lower levels. If lower levels have accumulated contaminants, the contaminants will become more concentrated in higher levels. Longer food chains result in greater biomagnification at each level. In this way, contaminants build up, or biomagnify, in the fatty tissues of consumers. ”Bioaccumulation” is the increase in contaminant concentrations in an animals' body over time, as the animal grows older. Bioaccumulation affects animals higher in the food chain through contaminant build-up over time. Older animals contain a higher concentration of contaminants because they have been consuming and storing contaminants longer. So the younger the animal harvested, generally the lower the amount of contaminants they will have.


Primary resource used: Inuit Tapiirit Kanatami http://www.itk.ca/environment/contaminants- wildlife-humans.php

Where Can I Find Out More About Contaminants?



U.S. Environmental Protection Agency

Persistent Organic Pollutants Booklet
http://www.epa.gov/oia/toxics/pop.pdf

Inuit Tapiirit Kanatami

Canadian Inuit organization. Excellent information on northern contaminants.
http://www.itk.ca/environment/contaminants-about.php

Taiga.net

Arctic Borderlands Ecological Knowledge Coop presentation with contaminants information
http://www.taiga.net/coop/synth/contaminants/contaminants.html
http://www.taiga.net/

Northern Contaminants Program

Database of publications on many contaminants topics
http://www.aina.ucalgary.ca/ncp/

International POPs Elimination Network

Numerous documents and reports on POPs
http://www.ipen.org/

Alaska Native Science Commission

Results from a project on Alaska Native traditional knowledge and contaminants
http://www.nativescience.org/html/arctic_contaminants.html

USFWS Arctic Environmental

Factsheets, reports, and Alaska environmental contaminant project Contaminants Program descriptions
http://alaska.fws.gov/fisheries/contaminants/index.htm

Conservation Science Institute

Think tank and research group devoted to solving environmental problems
http://www.conservationinstitute.org/ocean_change/ocean_pollution/contaminantsinalaska.htm

Alaska Community Action on Toxics

Alaska-based organization with numerous studies and resources on environmental contaminants
http://www.akaction.org/Northern_Contaminants_Health.htm

Arctic Council Arctic Contaminants Action Program (ACAP)

International group with many projects in Russia. Fact sheets and project descriptions on website.
http://acap.arctic-council.org/

Arctic Health (UAA-Institute for Circumpolar Health Studies)

Numerous environmental health reports and links
http://www.arctichealth.org/

Arctic Monitoring and Assessment Program

International organization that provides scientific information on arctic contaminant issues
http://www.arctichealth.org
http://grida.no/amap/