»Natural Radiation

Uranium, radium, plutonium, and most other radioactive materials have been present in Earth's crust since it was formed. Natural resources such as air , water, and soil may become contaminated when they come in contact with these naturally-occurring radionuclides.

»Radionuclides in the Ecosystem

This page provides an overview of radionuclides in the ecosystem.

Overview

An ecosystem is defined as a place having unique physical features, encompassing air, water, and land, and habitats that support plant and animal life. Radioactive elements, called radionuclides, are part of our ecosystem because they are a part of the air we breathe, the water we drink and the food we eat.

Ecosystem science focuses on the whole—the interaction among the water, air, land, and plants, animals and humans. Ecosystem science tells a story about elements in nature and their journey through the different natural systems that exist on Earth. Here is the general story of radionuclides in our ecosystem:

A tree’s roots digs down into a crack in the earth, prying the rock apart and turning the rock into soil. The rock contained radionuclides that, through this process, have now been brought to the surface.

Whether the radionuclides are natural or man-made, they move through the earth and can become part of the food chain. For example:

Some radionuclides attach to soil particles and migrate immediately into groundwater and streams and become a part of Earth’s water cycle. These can get deposited right back into the soil through evaporation and then rain.

Other radionuclides attach to soil particulates and end up in the air traveling with the atmospheric cycle.

Some radionuclides remain a part of the soil and are taken up by plants.

Animals consume these plants, drink the water and breathe the air. The radionuclides are now in the animals.

Humans eat the plants and the animals that ate the plants, drink the water and breathe the air. The radionuclides also are in humans.

The remains of plants and animals are returned to the earth and, over time, are crushed and pressured back into rock and the cycle begins again.

Radiological incidents, such as the 1986 nuclear reactor accident at Chernobyl, add large amounts of man-made radiation to an ecosystem. Recent studies on the ecology of the Chernobyl region have shown that, in the twenty years since the accident, the region’s ecosystem is rebounding and beginning to function normally. This means that ecosystems may be able to rid themselves of excess radiation.

»Radionuclides in Soil

This page describes the different types of radionuclides that can be found in Earth’s soil.

Overview

Radiation is everywhere, including in the soil. Radionuclides become a part of the soil in three ways:

as part of Earth’s original crust (primordial radionuclides)

produced and deposited by cosmic ray interactions (cosmogenic radionuclides) through man-made releases (man-made radionuclides and activities)

Primordial Radionuclides

Primordial radionuclides are left over from the creation of the Earth. They typically have half-lives of hundreds of millions of years. Examples include uranium-235, uranium-238, thorium-232, and potassium-40. Primordial radionuclides end up in soil as part of the rock cycle, which includes weathering.

Tree or plant roots dig down into cracks in the earth, prying the rock apart and turning it into soil. Natural radioactivity in soil varies on soil type, mineral make up and density. Man-made activities, such as mining, may accelerate the movement of primordial radionuclides into soil.

Cosmogenic Radionuclides

Radionuclides are continuously produced by bombardment of stable nuclides by cosmic rays, primarily in the atmosphere. These cosmogenic radionuclides can have long half-lives, but the majority have shorter half-lives than the primordial radionuclides. Cosmogenic radionuclides include carbon-14, tritium-3, and beryllium-7; worldwide, cosmic radiation is the primary source of these radionuclides.

Another way radionuclides become part of the soil is through natural cosmic radiation, radiation produced in outer space when heavy particles from other galaxies (nuclei of all known natural elements) bombard Earth.

Some of these radionuclides fall to Earth and are deposited on the soil.

Man-made Radionuclides and Activities

The third way radionuclides enter the soil is through man-made activities, such as the fallout from atmospheric testing of nuclear weapons and radiological events like the Chernobyl accident. Deposition studies of these activities indicate that radioactive particles travel around the world on streams of air. The weight of the particle and weather determine how soon they fall to the ground. Sometimes a heavy rain will bring the radioactive particles to the ground quickly. Improper disposal of radioactive material also may contribute to radionuclides in the soil.

Radionuclides in the soil can move into the water, air and even our food supply. Many different agencies are involved in setting standards and monitoring to keep us safe.

»Radionuclides in Air

This page describes the radionuclides commonly found in air.

Overview

Some radioactive materials - most of which are naturally occurring elements - are actually air pollutants. All of them, as a whole, are a relatively small proportion of the many elements and chemicals that are considered air pollution. Radon is the most significant of these elements, but most radon exposure stems from the indoor environment. Improving technology continues to minimize man-made radioactive air pollutants and monitor air quality.

Under EPA’s Clean Air Act, significant air pollutants include ozone, particulate matter, nitrogen dioxide, sulfur dioxide and lead. An additional 189 air pollutants are considered toxic in small amounts, including cadmium, benzene and radionuclides.

Air pollution affects everyone to some extent, but it is particularly harmful to the following groups:

Residents of major metropolitan areas, especially those areas with large industrial facilities;

Children, who tend to be more active outdoors and whose lungs are still developing; and

The elderly, especially sufferers from heart or lung disease.

Terrestrial Radiation (Radon)

The majority of our total radiation exposure stems from naturally-occurring radioactive materials, including uranium, thorium and radon. The most significant of these is radon — a colorless, tasteless, and odorless gas that comes from the decay of radium found in nearly all soils. Levels of radon vary throughout the country.

From the ground, radon migrates into homes and other buildings through cracks and holes in foundations or walls. Accumulated radon, trapped inside the buildings, may become a health hazard if the building is not properly ventilated. Radon in the air decays into radioactive polonium, which, if inhaled, can damage lung cells and can even lead to lung cancer.

In a January 2005 news release, the U.S. Surgeon General Richard H. Carmona noted that radon is the second leading cause of lung cancer in the United States, with more than 20,000 Americans dying each year from radon-related lung cancer. Only smoking causes more lung cancer deaths, and smokers exposed to radon are at an even higher risk than nonsmokers. Dr. Carmona also noted that “radon can be detected with a simple test and fixed through well-established venting techniques.”

Remember

Radon can be detected with a simple test and fixed through well-established venting techniques.

Cosmic Radiation

Another 8% of our radiation exposure comes from outer space, originating from our galaxy, other galaxies, and even our own sun. People in higher elevations, such as those who live in the mountains or fly on airplanes, experience higher doses of cosmic radiation. The atmosphere shields us from cosmic radiation. The more air that is between us and outer space, the more shielding that we have. While radon is absorbed through breathing, cosmic particles are absorbed through the skin.

Industrial Emissions

Nuclear power plants, mining facilities, and research facilities are man-made contributors to radioactive air pollutants. These industrial facilities account for less than 0.1% of the average American's total radiation exposure, much less than that from medical x-rays and various consumer products.

Health and the environment become a concern when radionuclides are released into the air as a result of facility accidents, nuclear weapons testing or acts of terrorism. Air monitors are used to track changes in radiation levels and assess the spread of contamination in the case of a radiation accident or incident.

»Radionuclides in Water

Overview

Radioactive materials can enter water in several ways:

By being deposited in surface water from the air

By entering ground water or surface water from the ground through erosion, seepage, or human activities such as mining, farming, storm water, and industrial activities.

By dissolving from underground mineral deposits as waster flows through them

Some radioactive particles dissolve and move along with the water. Others are deposited in sediments or on soil or rocks.

Most drinking water sources have very low levels of radioactive contaminants. Because these levels are very low, they are not considered to be a public health concern. Radon, from radium sources in the ground, is a special case of dissolved gas that can be at higher levels.

Health becomes a concern when radionuclides become concentrated in these bodies of water due to natural occurrences, accidental releases of radioactivity, or improper disposal practices.

Drinking Water

Drinking water can come from either ground water sources (e.g., wells) or surface water sources (rivers, lakes, streams, etc.). Water can pick up radioactive material as it flows through the rocks, soil or cracked cement surrounding a water source, therefore contaminating that water source.

Large metropolitan areas rely on surface water, while many rural areas use ground water. To find the source of your drinking water, check your annual water quality report or call your water supplier.

Most drinking water sources have very low levels of natural radioactive contaminants and are not considered to be a public health concern.

Water systems that are vulnerable to man-made radioactive contamination are required to undergo extensive monitoring to ensure that the drinking water is safe.

»Radionuclides in Private Wells

Overview

Approximately 15% of Americans rely on private drinking water supplies. Unlike public drinking water systems, wells generally are not routinely inspected. Therefore, these households must take special precautions to ensure the safety and quality of their drinking water supply.

Remember

Testing your home is the only way to determine radionuclide contamination!

Drinking water with elevated levels of radium and uranium – which are found in virtually all rock, soil, and water – may cause cancer after several years. Drinking water with elevated concentrations of uranium may affect a person over a much shorter time period.

If purification filters, storage tanks, and associated piping begin to collect radioactive wastes in elevated concentrations, these materials may require disposal in off-site facilities licensed to receive and dispose of radioactive waste.

Radon is a radioactive gas. It occurs naturally and is produced by the breakdown of uranium in soil, rock, and water. It can also dissolve into our water supply. As you shower or use your water for other household tasks, the gas can be released from the water into the air.

»Radionuclides in Public Drinking Water

Overview

In the past, drinking water suppliers used most of their resources treating contaminated source water.  Today, this treatment cost is greatly reduced through increased emphasis on protecting the water sources from ever becoming contaminated.  A source water protection program generally includes the following components:

Delineation: Identifying the area of land that water passes through to reach the drinking water intake.

Contaminant Source Inventory: Mapping the locations of potential sources of drinking water contamination.

Source Water Protection Area Management: Using regulatory controls, such as zoning and health ordinances, or non-regulatory controls, such as public education and technical assistance to businesses to keep contaminants out of drinking water supplies.

Contingency Planning: Coordinating special actions in case a sudden event (e.g., a flood or spill) threatens the drinking water supply.

While these programs are effective, protective measures are still taken at the plant that processes the water before it is distributed to the public.  The water is tested regularly and filters are in place to remove chemical and radiological contamination.

Drinking water with elevated levels of radium and uranium – which are found in virtually all rock, soil, and water – may cause cancer after several years. Drinking water with elevated concentrations of uranium may affect a person over a much shorter time period.

Radon is a radioactive gas. It occurs naturally and is produced by the breakdown of uranium in soil, rock, and water. It can also dissolve into our water supply. As you shower or use your water for other household tasks, the gas can be released from the water into the air.

When water treatment plants encounter radioactive contaminants, personnel evaluate the quantity and type of the material to determine if it may be discharged into the sanitary sewer system or if it requires disposal in off-site facilities licensed to receive and dispose of radioactive waste.