Cadmium, and Caribou
Some Facts About Heavy Metals and the Food
and Writing Connections >>
with "C" and ends in trouble? Cesium,
cadmium and caribou. Over the years scientists have studied the effects
materials that find their way into the environment and the foods we
Caribou and Cesium Alert
You might remember hearing about the explosion of the nuclear power plant in
Chernobyl (in the former Soviet Union) in 1986. The explosion caused a huge
radioactive cloud to drift across the northern atmosphere toward Alaska and
Canada. Part of the nasty radioactive material found in this cloud was an
element called radio-cesium. People were really nervous and anxious to learn
more about cesium and it's potential threat to their environment. Testing
was done to find out whether it was safe to eat caribou meat in Alaska and
Canada. Turns out that it was safe, but we were alerted to the possible health
threats that environmental polutants might have in the northern wildlife
Snow craters where caribou dig
Lichen-Winter caribou food
Photo courtesy USGS
Some of the research resulting from the Chernobyl accident led scientists
to take samples from the Porcupine caribou herd in the late 1980s. They
were particularly interested in looking at their cadmium levels.Cadmium
is a heavy metal. No, I'm not writing about electric rock 'n' roll here!
Heavy metals are a group of minerals that have always been found in our
natural environment in minute amounts until recent centuries, when the
orientation toward industrialization and production brought about our
many technological advances. Wastes containing some heavy metals are
released into the air from industries like mining, smelting, and manufacturing.
These heavy metals, including cadmium, attach themselves to dust particles
and float around until brought down to the earth by rain or snow. Northern
industrial sites release pollutants that can drift for miles before falling
to the earth in precipitation.
What does this have to do with caribou? We are all part of a huge food chain.
Caribou eat plants called lichens all winter long. Lichens are high in carbohydrates
and have the most food value of any plant available to the caribou. The extremely
short growing season in the Arctic (sometimes only 40 days lont) prevent
lichens from growing very much each season. This combination of factors leaves
lichens exposed to cadmium for many years. Caribou can be at risk for exposure
to cadmium more than other animals in the Arctic ecosystem.
Questions of Toxicity
When there are too many harmful things in the air, lichens die. This
is why they are sometimes called "indicator" species. They
can tell us if the air is clear and clean. Even in the remote arctic,
pollution has contaminated
lichens. Pollutants have drifted through the atmosphere, appeared in the lichens,
then in the flesh of the caribou--and then in the humans who eat the caribou.Testing
has been done on caribou to see if levels of cadmium would be dangerous to
the animals and to people who rely on caribou meat in their diet. It turns
out that animals (and humans) have natural methods for taking heavy metals
out of our bodies. Special proteins mop up excess metals and most of it ends
up in the kidneys(which are blood filters). Experts found that caribou meat
was safe. But it is best to limit your consumption of caribou kidneys.
Try This! Research Idea
Cadmium is naturally found in the ground along side another metal, zinc. When
mining for zinc, cadmium comes along and is processed with the zinc. We have
many uses for zinc.Research some products that contain zinc that we would use
in our every day lives. How might some of these products become contaminants
that could get into our bodies?