5. How Do Radioactive Materials Move Through the Environment to People?

aturally occurring radioactive materials Radionuclides can be removed from the air in Nare present in our environment and in several ways. Particles settle out of the our bodies. We are, therefore, continuously atmosphere if air currents cannot keep them exposed to radiation from radioactive atoms suspended. Rain or snow can also remove (radionuclides). Radionuclides released to them. the environment as a result of human When these particles are removed from the activities add to that exposure. atmosphere, they may land in water, on soil, or Radiation is energy emitted when a on the surfaces of living and non-living things. radionuclide decays. It can affect living tissue The particles may return to the atmosphere by only when the energy is absorbed in that resuspension, which occurs when wind or tissue. Radionuclides can be hazardous to some other natural or human activity living tissue when they are inside an organism generates clouds of dust containing radionu- where radiation released can be immediately clides. absorbed. They may also be hazardous when they are outside of the organism but close ➤ Water enough for some radiation to be absorbed by Radionuclides can come into contact with the tissue. water in several ways. They may be deposited Radionuclides move through the environ- from the air (as described above). They may ment and into the body through many also be released to the water from the ground different pathways. Understanding these through erosion, seepage, or human activities pathways makes it possible to take actions to such as mining or release of radioactive block or avoid exposure to radiation. This can liquids into sanitary sewers or rivers, lakes, minimize peoples’ exposure to additional streams or ground water. radiation resulting from human activities. Some radionuclides that reach either Radionuclides travel through the environ- groundwater or surface water will move with ment along the same pathways as other the water. Others will be deposited on the materials. They travel through the air, in surrounding soil or rocks. One important water (both groundwater and surface water), factor affecting their movement is how and through the food chain. Radionuclides thoroughly they dissolve in water (solubility). may enter the human body by eating or Another factor affecting movement is the drinking, by inhalation, or by absorption ability of the radionuclide to adhere to the through the skin. This fact sheet describes the surfaces of rocks or soil through which the pathways radioactive materials follow through water flows. the environment and into the body. ➤ Food Chain Pathways Through the Radionuclides in water or air may enter the Environment food chain. For example, plants are capable of ➤ Atmosphere absorbing radionuclides from water in the Radionuclides can be released into the air by same way as other minerals are absorbed. human activities. They can also be created in When animals drink water some of the the atmosphere by natural processes such as radionuclides in the water will remain in their the interaction of cosmic radiation with bodies. nitrogen to produce radioactive Carbon-14. Radionuclides from the air may settle on Page 2 • How Do Radioactive Materials Move Through the Environment to People?

the surface of plants. When animals eat the ➤ Through the Skin plants, they ingest the radionuclides that have Radionuclides can be absorbed through the settled from the air or have been absorbed skin’s surface, or can enter the body through a from the water. Plants and animals that will break in the skin. Another pathway is through eventually become food for people thus the injection of radionuclides as part of provide a pathway for radionuclides to move medical therapy or diagnosis. through the environment to people. Pathways and Low-level Pathways into the Human Body Radioactive Waste ➤ Ingestion Packaging and disposal facilities for low-level Anything that people eat can contain radio- radioactive waste are designed to minimize nuclides. The water that people drink can also the amount of radioactive material entering contain radionuclides. Some radionuclides are any of these pathways. Low-level waste is intentionally ingested as part of a medical placed in containers to prevent release of therapy or diagnostic procedure. radionuclides to the air during transportation Some of the radionuclides people ingest and handling, and to hold external radiation can remain in the body for long periods of levels below regulated limits. Low-level time while others are quickly eliminated, radioactive waste disposal facilities must be often within hours. located away from water. They are also designed to divert water away from the waste ➤ Inhalation and/or to collect and remove radionuclides Radionuclides suspended in the atmosphere from any water that might come in contact can enter our lungs. Some radioactive with the waste. This minimizes the amount of particles are exhaled, and some remain in the radioactive material that might inadvertantly lungs where the radiation they release strikes be released into water. Radioactive material the lung tissue. An important natural source from low-level waste that is not released into of radiation exposure is the radioactive gas air or water cannot enter the food chain or radon. Decay of radon atoms in the air gives reach people. rise to other radioactive atoms that are much ➤ more likely than radon to be retained in the For More Information lungs. These “radon decay products” are If you want to read more about pathways estimated by the United States Environmental radiation can follow through the environment, Protection Agency to be responsible for the reference listed below may be helpful. several thousand lung cancer deaths each • Raymond L. Murray, “Understanding year in the United States. Radioactive Waste”, Battelle Press, Columbus, Ohio, Fourth Edition, 1994.

This series of data sheets is based upon copyright material prepared by Ohio State University Extension under a grant from the Midwest Compact Commission. The material was reviewed and updated at Rutgers University, Department of Environmental Sciences by Alan Appleby, Ph.D., Martin Costello, M.S. and Steven Rose, M.S. Permission to use this material is gratefully acknowledged. November 1996