16.1 Natural and anthropogenic sources of environmental radiation
4 min read•july 31, 2024
Environmental radiation comes from both natural and human-made sources. Natural sources like cosmic rays, , and gas make up about 80% of our average annual exposure. The rest comes from medical procedures, industrial applications, and nuclear energy.
Understanding these sources is crucial for assessing radiation risks and protecting public health. Natural radiation levels vary based on location and geology, while human-made sources can change over time due to technological advances and regulatory changes.
Natural Radiation Sources
Cosmic and Terrestrial Radiation
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- originates from space consists of high-energy particles that interact with Earth's atmosphere producing secondary radiation
- Intensity increases with altitude and latitude
- Contributes approximately 13% of average annual radiation dose
- Terrestrial radiation emanates from naturally occurring radioactive materials in the Earth's crust including uranium, thorium, and their decay products
- Varies based on local geology (higher levels in granite-rich areas)
- Accounts for about 20% of average annual radiation exposure
Radon and Internal Radiation Sources
- Radon gas a decay product of uranium serves as the most significant natural source of radiation exposure for most populations
- Contributes approximately 50% of average annual radiation dose
- Concentrations vary dramatically between buildings and rooms due to soil composition and construction
- Radioactive isotopes in food and water contribute to internal radiation exposure through ingestion
- found in bananas, potatoes, and other foods
- present in all living organisms
- Together account for about 10% of average annual radiation dose
Anthropogenic Radiation Sources
Medical and Industrial Applications
- Medical procedures constitute the largest source of anthropogenic radiation exposure
- Diagnostic X-rays (chest X-rays, mammograms)
- (PET scans, thyroid treatments)
- for cancer treatment
- Account for 15-20% of average annual radiation exposure in developed countries
- Industrial applications utilize radioactive sources that can potentially lead to environmental contamination
- for non-destructive testing of materials
- in oil and gas exploration
- of medical equipment and food products
Nuclear Energy and Weapons
- and fuel cycle facilities release small amounts of radioactive materials during normal operation
- Potential for larger releases during accidents (Chernobyl, Fukushima)
- Contribute less than 0.1% to average annual radiation dose for most populations
- Nuclear weapons testing particularly atmospheric tests conducted in the mid-20th century has contributed to global environmental radiation levels
- Global fallout has decreased over time but still present in environment
- Contributes less than 1% to average annual radiation dose for most populations
Natural vs Anthropogenic Radiation
Relative Contributions
- Natural sources typically account for the majority (about 80%) of the average person's annual radiation exposure
- Radon gas alone contributes to approximately 50% of the average annual radiation dose
- Cosmic and terrestrial radiation combined account for about 33%
- Anthropogenic sources contribute the remaining 20% of average annual radiation exposure
- Medical procedures represent the largest anthropogenic source (15-20%)
- Nuclear power, weapons testing, and industrial sources contribute less than 1% combined
Variability Factors
- Relative contributions can vary significantly based on individual factors
- Lifestyle choices (living at high altitudes, frequent air travel)
- Medical history (number and type of procedures)
- Geographical location (local geology, proximity to nuclear facilities)
- Occupational exposure can significantly alter individual radiation doses
- Airline crew members receive higher cosmic radiation doses
- Nuclear power plant workers may have increased exposure
- Medical professionals working with radiation (radiologists, nuclear medicine technicians)
Radiation Levels: Variations
Geographical Variations
- Cosmic radiation exposure increases with altitude and latitude
- Higher doses at mountain elevations and polar regions
- Lower doses at sea level and equatorial regions
- Terrestrial radiation levels vary based on local geology
- Higher levels in areas rich in granite or uranium-bearing rocks (parts of Brazil, Iran)
- Lower levels in sedimentary rock areas
- Radon concentrations vary dramatically between locations
- Influenced by soil composition, building materials, and ventilation
- Can differ significantly even between adjacent buildings
Temporal Variations
- Anthropogenic radiation levels may show temporal variations
- Short-term spikes related to nuclear accidents (Chernobyl, Fukushima)
- Long-term changes due to weapons testing or changes in medical practices
- Natural radiation levels can exhibit long-term variations
- Climate change potentially altering distribution of natural radionuclides
- Geological events (earthquakes, volcanic eruptions) affecting radon release
- Long-term environmental monitoring programs track changes in radiation levels
- Essential for identifying potential sources of contamination
- Provide data for assessing long-term trends and health impacts
Key Terms to Review (24)
ALARA Principle: The ALARA principle, which stands for 'As Low As Reasonably Achievable,' is a radiation safety concept aimed at minimizing radiation exposure to individuals while still achieving the desired outcome. This principle emphasizes that all exposure should be kept to the lowest possible levels, taking into consideration social, economic, and technological factors.
Becquerel: The becquerel (Bq) is the SI unit of measurement for radioactivity, defined as one disintegration or decay event per second. This term is essential in understanding the activity of radioactive substances, which can vary widely and impacts how we assess exposure and risks associated with radiation.
Biological half-life: Biological half-life refers to the time required for the body to eliminate half of a substance, such as a radioactive isotope or a drug, through biological processes like metabolism and excretion. This concept is crucial in understanding how long a substance remains in the body and its potential effects on biological systems, especially when considering exposure to environmental radiation or therapeutic interventions.
Carbon-14: Carbon-14 is a radioactive isotope of carbon with a nucleus containing 6 protons and 8 neutrons, commonly used in radiometric dating to determine the age of organic materials. Its presence in the atmosphere and incorporation into living organisms allows scientists to measure the decay of carbon-14 to estimate when an organism died, connecting it to understanding natural and anthropogenic sources of environmental radiation.
Chernobyl Disaster: The Chernobyl Disaster was a catastrophic nuclear accident that occurred on April 26, 1986, at the Chernobyl Nuclear Power Plant in Ukraine. It is recognized as one of the worst nuclear disasters in history, resulting in widespread radioactive contamination and significant health and environmental impacts, which connects it to natural and anthropogenic sources of environmental radiation.
Cosmic radiation: Cosmic radiation refers to high-energy particles originating from outer space, including protons, electrons, and atomic nuclei, that reach the Earth and contribute to the background radiation exposure experienced by all living organisms. This form of radiation is a key component of natural environmental radiation sources and poses various health risks depending on exposure levels and the type of radiation involved.
Dose Rate: Dose rate refers to the amount of radiation exposure delivered per unit time, typically expressed in units such as grays per hour (Gy/h) or sieverts per hour (Sv/h). Understanding dose rate is crucial, as it helps to evaluate the severity of radiation exposure and its potential biological effects, especially in acute situations. The dose rate significantly influences the phases and symptoms of radiation sickness, as well as how environmental radiation sources impact living organisms over time.
Ecological effects of radiation: Ecological effects of radiation refer to the impact that radiation exposure has on ecosystems, including plants, animals, and the overall health of the environment. This encompasses both natural radiation from sources like cosmic rays and radioactive elements in the earth, as well as anthropogenic radiation from human activities such as nuclear power generation and medical uses. Understanding these effects is crucial for assessing risks and implementing protective measures for wildlife and habitats.
Environmental Protection Agency (EPA): The Environmental Protection Agency (EPA) is a U.S. federal agency established in 1970 to oversee and enforce national policies aimed at protecting human health and the environment. Its work includes regulating pollutants, managing hazardous waste, and monitoring environmental radiation from both natural and human-made sources. The EPA plays a crucial role in mitigating the risks associated with environmental radiation, ensuring public safety through strict guidelines and scientific research.
Fukushima Daiichi Accident: The Fukushima Daiichi accident was a catastrophic nuclear disaster that occurred on March 11, 2011, at the Fukushima Daiichi Nuclear Power Plant in Japan. It resulted from a massive earthquake and tsunami that disabled the plant's power supply and cooling systems, leading to the release of radioactive materials into the environment. This incident highlighted the risks associated with nuclear energy and underscored the importance of safety measures in managing both natural and anthropogenic sources of environmental radiation.
Industrial radiography: Industrial radiography is a non-destructive testing technique that uses ionizing radiation to inspect materials and structures for internal flaws. This method is essential in various industries such as manufacturing, construction, and aerospace, where it helps ensure the integrity and safety of components by detecting issues like cracks, voids, or weld defects without damaging the item being tested.
Medical imaging: Medical imaging refers to the technique and process used to create visual representations of the interior of a body for clinical analysis and medical intervention. It plays a crucial role in diagnosing, monitoring, and treating diseases, and it encompasses various modalities such as X-rays, MRI, CT scans, and ultrasound. These imaging techniques help healthcare professionals assess health conditions and plan appropriate treatments while considering the radiation exposure from both natural and anthropogenic sources.
Nuclear medicine: Nuclear medicine is a medical specialty that uses radioactive substances for diagnosis and treatment of diseases, particularly in the field of imaging and targeted therapies. It allows healthcare professionals to visualize physiological processes in the body, providing critical information about the function of organs and tissues, which aids in the detection of various medical conditions. This field bridges the gap between medicine and radiology by utilizing both natural and anthropogenic sources of radiation.
Nuclear power plants: Nuclear power plants are facilities that generate electricity through the process of nuclear fission, where the nucleus of an atom splits into smaller parts, releasing a significant amount of energy. This energy is used to produce steam, which drives turbines to generate electricity. These plants are critical in the context of environmental radiation due to their reliance on radioactive materials and their potential to release radiation during accidents or normal operations.
Nuclear Regulatory Commission (NRC): The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government responsible for regulating the nation's civilian use of nuclear materials and ensuring the safety and security of nuclear power plants. The NRC plays a critical role in overseeing the licensing, operation, and decommissioning of nuclear facilities, while also enforcing regulations that protect public health and the environment from harmful radiation exposure.
Potassium-40: Potassium-40 is a naturally occurring radioactive isotope of potassium, making up about 0.012% of all potassium found in nature. This isotope is significant because it contributes to the natural background radiation and is one of the key sources of radiation exposure from food and environmental sources. Potassium-40 plays a role in both biological processes and geological dating, highlighting its importance in understanding environmental radiation levels.
Radiation contamination: Radiation contamination refers to the unwanted presence of radioactive materials on surfaces, in the air, or within living organisms, which can pose health risks to humans and the environment. This contamination can result from both natural sources, like radon gas from soil, and anthropogenic sources, such as nuclear power plant accidents or improper disposal of radioactive waste. Understanding radiation contamination is crucial for managing environmental safety and protecting public health.
Radiation therapy: Radiation therapy is a medical treatment that uses high doses of radiation to kill or damage cancer cells and shrink tumors. It is a crucial part of cancer treatment, often used in conjunction with surgery or chemotherapy, and can be delivered externally via a machine or internally through radioactive implants. The effectiveness of radiation therapy is influenced by the type of cancer, its stage, and the patient's overall health.
Radon: Radon is a colorless, odorless, radioactive gas that is produced naturally from the decay of uranium in soil and rock. It is a significant environmental health concern as it can accumulate in buildings and is linked to lung cancer when inhaled over extended periods.
Sievert: The sievert (Sv) is a unit of measure used to quantify the biological effects of ionizing radiation on human tissue. It is particularly significant in radiobiology, where understanding radiation exposure and its potential harm to living organisms is crucial. The sievert connects the physical dose of radiation, measured in grays (Gy), to the effective dose, accounting for the type of radiation and its impact on different tissues, highlighting the importance of radiation protection and environmental safety.
Sterilization: Sterilization is the process of eliminating all forms of microbial life, including bacteria, viruses, fungi, and spores from a surface, liquid, or living tissue. This is crucial in various fields such as healthcare, food safety, and environmental control, where the presence of microorganisms can pose significant health risks. Understanding sterilization helps assess the impacts of natural and human-induced radiation sources on biological systems and the environment.
Terrestrial radiation: Terrestrial radiation refers to the natural radiation emitted from the Earth itself, primarily from radioactive isotopes present in soil and rocks. This form of radiation contributes to the overall background radiation that humans are exposed to and varies depending on geographic location, geology, and human activities. Understanding terrestrial radiation is crucial for assessing natural and anthropogenic sources of environmental radiation and their potential impacts on health.
Time, Distance, Shielding: Time, distance, and shielding are key principles used to minimize exposure to radiation. By reducing the time spent near a radiation source, increasing the distance from that source, and using appropriate shielding materials, individuals can significantly lower their risk of harmful effects from both natural and anthropogenic sources of environmental radiation. These principles are crucial for ensuring safety in environments where radiation is present.
Well logging: Well logging is the process of recording geological and hydrological information about subsurface formations through the use of various instruments and techniques. This data is critical for understanding the composition, porosity, permeability, and other characteristics of rock layers, which can help in evaluating potential natural resources, including oil, gas, and groundwater. Well logging also plays a key role in assessing environmental radiation sources by providing insights into the geological settings that can affect radiation levels.