In this video segment from Nature: “Radioactive Wolves”, biologists monitor how several animal species have been affected by long-term radiation exposure in the “Exclusion Zone” surrounding the site of the 1986 Chernobyl nuclear disaster.
- What does the existence of newborn wolf pups in the Exclusion Zone prove about the local wolf population?
- Is there any evidence that long term radiation exposure is affecting the health of white lab rats?
- What is the Red Forest?
- Why is a windy day particularly dangerous in the Zone?
- What is the rate of genetic abnormalities in the dormice in the Zone? What impact does this have on the dormouse population more generally?
- How does the reproduction rate of dormice inside the Zone compare with those outside it? What might be responsible for this?
We tend to think of radiation as something inherently harmful to living things. When getting X-rayed, we shield ourselves with heavy lead aprons from as much of the processes’ radiation as possible; we use radiation therapy to destroy cancerous cells; and we are grimly aware from grainy newsreel footage of the horrific damage done to human bodies by the radioactive blasts of the Hiroshima and Nagasaki atom bombs in World War II. These are all, however, exceptional instances of artificially intensified radiation.
Radiation is most simply defined as the process by which energy particles or waves move through space. It is commonly differentiated into “ionized” and “non-ionized” types, with the latter including such relatively safe and familiar phenomena as heat, light, and radio waves. Ionized radiation, however, has sufficient energy to “ionize” atoms by stripping them of electrons, and in sufficient quantities, it can be particularly damaging to the cell structure and genetic code (DNA) of living organisms.
A certain amount of ionized radiation—called “background radiation”—is all around us, all the time. It is a naturally occurring part of the environment, coming from both outer space in the form of “cosmic” radiation, and the earth itself as “terrestrial” radiation. It is common in certain building materials like brick and stone, and certain potassium-rich foods like bananas and Brazil nuts. It is found in the air that we breathe, which is laced with radon gas from the earth’s crust. Overall, these natural sources account for about half of a U.S. citizen’s total annual average radiation exposure, with the other half coming mostly from diagnostic medical procedures like X-rays and CT scans. No adverse health effects have been discerned from normal doses of radiation exposure.
Occasionally, however, humans have been exposed to much higher levels of radiation. Firefighters and other first-response emergency workers at the Chernobyl nuclear power plant meltdown in 1986 received up to 16,000 times the maximum recommended annual radiation exposure. Such intensely high exposure—even if only for a short duration—destroys cells and triggers Acute Radiation Syndrome, the massive and painful organ failure which killed 28 of the emergency workers within three months.
Lower doses of radiation over longer periods of time tend to damage or alter the DNA of irradiated cells rather than killing them outright. Cancers—often undetected for extended latency periods—are the most common consequence of low-level radiation. Genetic effects include an increased risk of still birth and low birth weight, infant and childhood mortality, and congenital abnormalities and mutations that may or may not affect later generations. Research on humans who have suffered long-term exposure is inconclusive and heavily debated, but research in the Exclusion Zone surrounding the site of the Chernobyl disaster suggests that while animal populations there may suffer a higher rate of individual birth defects, their overall health is robust and their population is booming.
Science in Personal and Social Perspectives – Content Standard F
As a result of activities in grades 5-8, all students should develop understanding of
- Personal health
- Natural environments may contain substances (for example, radon and lead) that are harmful to human beings. Maintaining environmental health involves establishing or monitoring quality standards related to use of soil, water, and air.
- Populations, resources, and environments
- Causes of environmental degradation and resource depletion vary from region to region and from country to country.
- Risks and benefits
- Risk analysis considers the type of hazard and estimates the number of people that might be exposed and the number likely to suffer consequences. The results are used to determine the options for reducing or eliminating risks.
- Students should understand the risks associated with natural hazards (fires, floods, tornadoes, hurricanes, earthquakes, and volcanic eruptions), with chemical hazards (pollutants in air, water, soil, and food), with biological hazards (pollen, viruses, bacterial, and parasites), social hazards (occupational safety and transportation), and with personal hazards (smoking, dieting, and drinking).
As a result of activities in grades 9-12, all students should develop understanding of
- Personal and community health
- Hazards and the potential for accidents exist. Regardless of the environment, the possibility of injury, illness, disability, or death may be present. Humans have a variety of mechanisms—sensory, motor, emotional, social, and technological—that can reduce and modify hazards.
- Natural and human-induced hazards
- Human activities can enhance potential for hazards. Acquisition of resources, urban growth, and waste disposal can accelerate rates of natural change.
- Some hazards, such as earthquakes, volcanic eruptions, and severe weather, are rapid and spectacular. But there are slow and progressive changes that also result in problems for individuals and societies. For example, change in stream channel position, erosion of bridge foundations, sedimentation in lakes and harbors, coastal erosions, and continuing erosion and wasting of soil and landscapes can all negatively affect society.
- Natural and human-induced hazards present the need for humans to assess potential danger and risk. Many changes in the environment designed by humans bring benefits to society, as well as cause risks. Students should understand the costs and trade-offs of various hazards—ranging from those with minor risk to a few people to major catastrophes with major risk to many people. The scale of events and the accuracy with which scientists and engineers can (and cannot) predict events are important considerations.
- Science and technology in local, national, and global challenges
- Humans have a major effect on other species. For example, the influence of humans on other organisms occurs through land use—which decreases space available to other species—and pollution—which changes the chemical composition of air, soil, and water.