What Are Contaminants?

The term "environmental contaminant" is another name for pollution. A contaminant is a substance that is where it shouldn't be and is at high enough levels to have a negative effect on our health or on the health of animals or plants. A contaminant is any potentially undesirable substance (physical, chemical or biological). It usually refers to the introduction of harmful human-made substances. However, some substances that may have harmful effects at high levels, like cadmium, occur naturally in ecosystems and may also be introduced through human activities. Tissue samples taken from Porcupine caribou, for example, show traces of cadmium which is naturally present in the lichens the caribou eat.

Contaminants can be man-made substances produced by factories, such as DDT or toxaphene. It is the substance's long life and its ability to spread over a wide area that makes an industrial contaminant such a problem. Chemicals used in other parts of the world enter into the upper atmosphere and end up falling to the ground here, contaminating our homelands. Contaminants may be found in soil, plants, air, water, sea animals, land animals, and birds.

My grandchild told me "Rain comes down and it goes back up again."

Source: Yukon First Nation's Elder's Council, Council for Yukon Indians


The types of contaminants measured in wildlife include: organochlorines (OCs), heavy metals, and radionuclides.

Organochlorides are almost always human-made chemicals. They can be pesticides or industrial chemicals used in processes such as making plastics. They may be present in old electrical transformers, and they may be formed when burning garbage. OCs dissolve in fats and oils, therefore they are found in the fat of animals. OCs tend to be the contaminants of greatest concern in the food chain. The most common OCs measured in Arctic wildlife are an industrial chemical called PCBs, and the pesticides toxaphene, DDT, and chlordane.

Heavy metals are found as elements naturally present in rocks and soils. They include mercury, cadmium, and lead. Metal mining and smelting can result in additional human-made releases of metals, such as cadmium and mercury. Also, the creation of reservoirs can cause mercury to be released from flooded areas. Some metals are essential for life at low levels, for example iron and zinc, while others, such as cadmium, mercury, and lead are toxic to most living things at relatively low levels. Metals tend to accumulate in specific parts of the body. For example, lead accumulates in the bones, mercury and cadmium accumululage in kidney and liver, and the form of mercury known as methylmercury accumulates evenly throughout the body.

Radionuclides are radioactive elements that, like heavy metals, are naturally present in rocks and soils. They may also be human-made. Certain kinds of radionuclides have been released to the environment because of activities such as atmospheric testing of nuclear weapons, nuclear waste dumping, and incidents such as the 1986 Chernobyl nuclear accident. Cesium is the human-made radionuclide that is most often found in the north. Polonium is the most commonly found natural radionuclide. Uranium is a natural radionuclide that can be found in increased levels as a result of uranium mining. Although there are natural and local sources of some of the above-noted contaminants within the north, most human-made contaminants come from sources outside the north.

Source: Highlights of the Canadian Arctic Contaminants Assessment Report,
Department of Indian and Northern Affairs, Canada

More information on heavy metals, trace elements, radionuclides or organochlorines:

Heavy Metals
Cadmium (Cd)
Lead (Pb)
Mercury (Hg)

2,4'-DDT (2,4'-DDT)
4,4'-DDD (4,4'-DDD)
4,4'-DDE (4,4'-DDE)
4,4'-DDT (4,4'-DDT)
chlordane (chlordane)
Chlorine (Cl)
dieldrin (dieldrin)
dioxin (dioxin)
endosulfan (endosulfan)
gamma hexachlorocyclohexane (g-HCH)
heptachlor (heptachlor)
hexachlorobenzene (HCBZ)
mirex (MIREX)
sum of chlorobornane congeners (s-TOX)
toxaphene (toxaphene)
PCB's (PCB110)

Cesium (Cs)
iodine (iodine)
plutonium (plutonium)
strontium 90 (SR 90)
tritium (tritium)
uranium (uranium)

Trace Elements
Aluminum (Al)
Arsenic (As)
Chromium (Cr)
Copper (Cu)
Nickel (Ni)

The contaminants component of the database contains databases from other sources. These are: