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NORM: Radioisotopes in the backyard
Posted on Feb 1, 2015 by Safe Radiation
Every now and then at Safe Radiation, we receive a phone call or a visit by a concerned person about the potential of being exposed to radioactivity at home. As a professional in the field of ionising radiation safety, Safe Radiation staff attempt to genuinely respond and often guide people to authentic sources of information and advice.
The truth is, humans cannot escape radiation exposure. Radioisotopes are an integrated part of our habitat; they are present in the soil, the air we breathe, and even in the food we eat. Hence daily encounters with radioactivity is unavoidable. Because we eat and breathe radioisotopes, they become a part of our body. Everywhere we go, we carry radioactivity with us.
Safe Radiation staff measuring natural radioactivity from the ground.
Modern day instruments can detect very low amounts of radioactivity in a specimen. Presence of radioactivity in a material, however, does not automatically mean an unacceptable radiation dose for human contact or consumption. In fact there are many scientific applications of low-level radioactivity detection, such as geological and archaeological dating, sediment transport and soil erosion measurements, and air and water mass movement studies to name a few. Several research articles appear in publications such as the Journal of Environmental Radioactivity. In our region, South Pacific Environmental Radioactivity Association (SPERA) holds biennial conferences with presentations about radioisotopes in the environment.
Some minerals carry higher concentrations of naturally occurring radioisotopes. For this reason, many places in the world are more radioactive than the others.
Plenty of information is available at authentic web sites about radioactivity in the natural environment. United Nations Scientific Committee on Atomic Radiation (UNSCEAR) publishes information on the worldwide distribution of natural radioactivity and radiation dose to human populations. According to UNSCEAR 2008, on average, the world population receives a radiation dose of 2.4 mSv (milli Sievert) per year, but the values vary from one to another population area. The typical range of annual radiation dose for different population groups as reported by UNSCEAR is from 1 to 13 mSv per year. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has published fact sheets about radiation in the environment around us in Australia. Fact Sheet Link.
These radioisotopes of uranium and thorium primordial series are present on the earth crust since its formation. During one hour of time, more than 3 million radioactive atoms go through nuclear disintegration in a kilogram of natural soil. Calculation based on reported global average (UNSCEAR 2008)