Many materials - both natural and manmade -that we come into contact with in our everyday lives are radioactive, as I have mentioned from my past posts. These materials are composed of atoms that release energetic particles or waves as they change into more stable forms. These particles and waves are referred to as radiation, and their emission as radioactivity.

Cosmic Radiation
Cosmic radiation is high-energy gamma radiation that originates in outer space and filters through our atmosphere.

• Sea Level= 26 mrem/year
• Atlanta (1,050 ft)= 31 mrem/year
• Denver (5,300 ft)= 50 mrem/year
• Minneapolis (815 ft)= 30 mrem/year
• Salt Lake (4,000 ft)= 46 mrem/year

Terrestrial Radiation
Terrestrial sources are naturally radioactive elements in the soil and water such as uranium, radium, and thorium. Average levels of these elements are 1 pCi/g of soil.

• U.S. (average)= 26 mrem/year
• Denver, CC= 63 mrem/year
• Nile Delta, Egypt= 350 mrem/year
• Paris, France= 350 mrem/year
• Kerala, India= 400 mrem/year
• McAlpe, Brazil= 2,448 mrem/year
• Pocos de Caldas,Brazil= 7,000 mrem/year

Buildings
Many building materials, especially granite, contain naturally radioactive elements.

• U.S. Capitol Bldg= 85 mrem/year
• Statue of Liberty= 325 mrem/year
• Grand Central Sta= 525 mrem/year
• The Vatican= 800 mrem/year

Radon
Radon levels in buildings vary, depending on geographic location, from 0.1 to 200 pCi/liter.

• Average indoor radon levels= l.5 pCi/liter
• Occupational working limit= 1 00.0 pCi/liter

Because the radioactivity of individual samples varies, the numbers given here are approximte or represent an average. They are shown to provide a perspective for concentrations and levels of radioactivity rather than dose.

mrem=millirem
pCi=picocurie

Food
Food contribues an average of 20 mrem/year, mostly from potassium-40, carbon-14, hydrogen-3, radium-226, and thorium-232.

• Beer= 390 pCi/liter
• Tap Water= 20 pCi/liter
• Milk= 1,400 pCi/liter
• Salad Oil= 4,900 pCi/liter
• Whiskey= 1,200 pCi/liter
• Brazil Nuts= 14 pCi/g
• Bananas= 3 pCi/g
• Flour= 0.14 pCi/g
• Peanuts 8 Peanut Butter= 0.12 pCi/g
• Tea= 0.40 pCi/g

Medical Treatment
The exposures from medical diagnoses vary widely according to the required procedure, the equipment, and film used for X-rays, and the skill of the operator.

• Chest X-Ray= 10 mrem
• Dental X-Ray= 100 mrem

Consumer Goods

• Cigarettes-2 packs/day (polonium-210)= 8,000 mremlyear
• Color Television= <>
• Gas Lantern Mantle (thorium-232)= 2 mrem/year
• Highway Construction= 4 mrem/year
• Airplane Travel-39,000 ft (cosmic)= 0.5 mrem/year
• Natural Gas/Heating and Cooking (radon-222)= 2 mrem/year
• Phosphate Fertilizers= 4 mrem/year
• Porcelain Dentures (uranium)= 1,500 mrem/year
• Radioluminescent Clock(promethium-147)= <1>
• Smoke Detector(americium-241)= 0.01 mrem/year