13 Radon A Deadly Carcinogen in the Geologic

13 Radon: A Deadly Carcinogen in the Geologic Environment Joni Osborn, Western Oregon University Faculty Advisor: Steve Taylor, Ph. D Abstract Radon: A Deadly Carcinogen in the Geologic Environment Radon is a naturally occurring noble gas that results from radioactive decay in uranium-bearing bedrock and regolith. Radon occurs in a variety of geologic settings around the world, including the United States. Bedrock sources most associated with radon include metamorphic rocks and granites, black shales, feldspathic glacial deposits, and uranium ores. Health hazards associated with this gas include lung and stomach cancers, caused primarily by inhalation or ingestion. Radon exposure increases chances of lung cancer deaths in smokers and miners who work in underground enclosures. Radon hazard mapping helps locate risk areas and guides public health protection. Global hot spots for radon exposure include the Sierra Nevada-Rocky-Appalachian mountain regions of the U. S. , glacial terrains of the upper Midwest, Great Britain, Norway, and the Czech Republic. This paper provides an overview of the geochemistry behind radon occurrence and presents examples of mitigation projects from around the world. Contact Name: Joni Osborn Organization: Western Oregon University Dept. of Earth and Physical Sciences Email: jeggleston 09@wou. edu Introduction Radon is a radioactive, naturally occurring noble gas. A noble gas is odorless, colorless, tasteless and has relatively low chemical reactivity. Radon is the product of the decay of radium. Radium is the product of the radioactive decay of uranium (Appleton, 2007). Radon gas is found throughout the United States and the world. Radon gas disperses in the open air but accumulates in enclosed areas. It is in these enclosed areas where increased levels of radon become a health hazard. There are ways to mitigate radon gas in homes and buildings. Extensive amount of epidemiological data has accumulated over several decades relating to studies of the incidence of lung cancer in miners. These studies consistently demonstrated an increase in lung cancer incidence with exposure to radon decay products (Appleton 2005). Figure 1. Orange counties moderate potential, Yellow counties low potential of radon Case Examples According to the Environmental Protection Agency (EPA), twenty-three out of thirty-six Oregon counties have the potential for moderate levels of radon with the other sixteen counties have the potential of low levels of radon (EPA 2010). Polk County falls into the potential of low level. Figure 1. According to Appleton (2005) Studies of thousands of miners, some with follow-up periods more than thirty years, have been conducted in uranium, iron, tin, and fluorspar mines in Australia, Canada, China, Europe and the United States. The results consistently demonstrated an increase in lung cancer incidence with exposure to radon decay products. The miner studies prove low exposures over longer periods produced greater lung cancer risk than high exposures over short periods (Appleton, 2005). Geologic Process/Phenomena The radioactivity decay of Uranium produces the radioactive decay of radium which radon gas is the result. Radon gas (222 Rn) is one of three radon isotopes 219 Rn, 220 Rn, and 222 Rn. Uranium is found in granite, uranium-enriched, and phosphatic rocks, uraniferous metamorphic rock. Granites in southwestern England, the Czech Republic, and Germany have high radon levels. The United States has a variety of land formations that produce high levels of radon. Some of these are uraniferous metamorphic rocks in the Rocky and Appalachian Mountains and the Sierra Nevada. Marine black shales from Ohio to Colorado contain high amounts of radon (Appleton, 2005). Figure 2. Radon enters buildings and homes by 3 pathways. Figure 3. Radon gas migrates up from the ground underneath the basements of foundations following minute pathways. Cracks in the foundations, floors, walls and areas below grade, gaps around service pipes entering the house, are all potential entrances for radon gas. Houses in the United States with basements have a greater incident of higher radon levels (Appleton 2005). Household water sources that come from enclosed groundwater have the potential of having higher levels of radon because there is not a way to allow the degassing of the water. Aeration of radon laden water while running the shower or faucets allows the radon gas to enter the air in the building. Building products that have been made with radioactive shale add to high radon concentrations. Health Connection Radon is the number one cause of lung cancer among non-smokers, according to EPA estimates. Radon is responsible for about 21, 000 lung cancer deaths every year (EPA 2010). Figure 4. Radon causes 11% of lung cancer deaths among smokers (most of whom die of smoking) but 23% of never-smokers (Appleton, 2005). The U. S. EPA estimates that radon in drinking water causes about 168 cancer deaths per year, 89% from lung cancer caused by breathing radon released from water, and 11% from stomach cancer caused by drinking radon-containing water (Appleton, 2005). Figure 4. A cancerous lung Summary Radon mapping helps to determine if radon protective measures may be needed in new buildings, cost-effectiveness of radon monitoring of existing buildings, and to provide a radon assessment for home buyers and sellers (Appleton, 2007). Since radon can seep into homes through cracks in the foundations, service pipe entrances, or any opening no matter what size, eliminating the radon is essential. This means keeping the radon out, remove what is inside or dilute it with fresh air. To keep radon out seal all openings and cracks. Use a low ventilation Figure 3. Keller, 2011 Environmental Geology Prentice fan that pumps air from the basement to above the roof line. Diluting the radon gas with fresh air is Hall 511 best for unused basements because it is not economical because of increased heating or cooling costs (The Natural Handyman, 2009) References Appleton, J. D. , 2007, Radon: Sources, Health Risks, and Hazard Mapping: Royal Swedish Academy of Sciences, 85 -88. Appleton, J. Donald, 2005, Essentials of Medical Geology: British Geological Survey, 227 -262 Environmental Protection Agency, EPA Map of Radon Zones, URL: http: //www. epa. gov/radon/zonemap. html The Natural Handyman, 2009, Radon in the Home. . . How Dangerous is it. . . Really? Internet Web Resource, URL: http: //www. naturalhandyman. com/iip/infsisters/infradon. html Figure 2. Potential Radon map