Arctic Research - Radioactivity in Caribou

This content was archived on June 24, 2013.

Are you a Canadian northerner? Are you concerned about the radioactive substances found in the food you consume (e.g. caribou)? Are you also concerned about the effects these substances may have on your health? If so, this factsheet will help you understand the meaning of radioactivity, it will identify the radioactive substances found in caribou and it will also identify whether caribou is hazardous or not to one's health.

What is Radioactivity?

Radioactivity is the property of certain substances to give off high energy radiation. We are all exposed to small amounts of radiation from our environment. It comes from the sky, the earth, the walls of our homes, even from the air we breathe. Radiation in the form of x-rays is used by doctors and dentists to see inside the body. The small amounts of radiation we receive from the environment or from x-rays have not been found to be harmful.

Natural or Artificial Radioactivity?

Radioactive substances can be natural or artificial. Many natural radioactive substances have been around since the beginning of time. For example, all rocks and soils contain small amounts of the radioactive element uranium. Uranium produces a radioactive gas called radon which seeps out of the ground slowly. After a few days the radon changes into two other radioactive substances, lead-210 (radioactive form of lead) and polonium-210 which can remain in the environment for many years.

Lead-210 and polonium-210 are naturally radioactive substances. They are part of the natural environment everywhere on earth. The levels of lead-210 and polonium-210 in caribou have not changed since measurements began in the 1960's. Indeed, these levels have probably remained unchanged for thousands of years.

Another natural radioactive substance is potassium-40 (radioactive form of potassium), which is a part of all living things.

About 50 years ago artificial radioactive substances began to enter the environment, mainly from atomic bomb tests. There were a great number of bomb tests during the 1950's and early 1960's. In 1963 the USA, Russia, and Great Britain agreed to stop testing bombs in the atmosphere. In 1980 China was the last country to explode an atomic bomb in the atmosphere. In 1996 all the major powers signed a treaty forbidding the testing of atomic bombs anywhere on earth or in space.

Artificial radioactive substances have also entered the environment from accidents at atomic power plants, such as the one at Chernobyl, Ukraine, in 1986. Whether released from atomic bomb tests or from reactors, radioactive substances are carried great distances by air and ocean current. One of the most important of these substances is radiocesium.

The levels of radiocesium in caribou were quite high in the early 1960's when many atomic bombs were being tested. The levels have been falling steadily since then, with only a slight increase after the 1986 Chernobyl accident. Today radiocesium in caribou is barely measurable.

How Does Radioactivity Get Into Caribou?

Caribou eat lichens, which act like sponges and collect radioactive substances that fall on them from the air. The radioactivity is found in the meat and organs, and is passed on to people who eat caribou.

Are Caribou Safe to Eat?

The levels of radioactivity found in Canadian caribou today are not enough to cause any harm to your health. This is true even if you eat a large amount of meat and other organs.

In 1989/90 the residents of Baker Lake, Rae-Edzo, Old Crow, Aklavik, and Fort McPherson took part in a special study to measure the amount of radiocesium in their bodies. By placing a special detector close to a person's body, we are able to tell how much radiocesium is in the body. Health Canada found that the amount of radiation produced in the body of someone eating a half pound of caribou every day is equivalent to about one chest x-ray per year.

Based on research, Health Canada concluded that caribou was a safe and nutritious food item. Caribou today have even lower levels of radiocesium, so the amount of radiation received by caribou-eaters is also lower.

We know that caribou also contain lead-210 and polonium-210. These substances are not as easy to measure as radiocesium. This is because lead-210 and polonium-210 give off a kind of radiation that is not "seen" by our detectors. If we know the amount of caribou and other country foods people eat, we can have an idea of how much lead-210 and polonium-210 are in their bodies. The amount of radiation a person receives from lead-210 and polonium-210 is about the same as from other natural sources of radiation in the environment.

Conclusion

Over the past few years, the safety associated to the consumption of caribou has been studied and balanced against the benefits of eating this traditional food.

Artificial radioactivity levels from sources like bomb testing and the Chernobyl accident are extremely low and are getting lower.

Natural radioactivity is part of the lichen-caribou-human food-chain, and always has been.

Pesticides and chemicals like PCBs and toxaphene are not a problem with caribou as they sometimes are with fish and marine mammals because these chemicals are not part of the lichen-caribou-human food-chain.

If consumption of traditional food resources, particularly fish and wildlife, were discontinued, the mineral nutrition of most northerners would be compromised to such an extent that nutritional deficiencies could occur.