© 2017 MRIC Global

Dr. Tsubokura's Radiation Lecture Vol.64

November 13, 2019

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

 

127. Many consumer products in your home also use radioactive substances

Annually, we Japanese people are exposed to approximately 2.1 millisieverts of radiation from various radioactive substances. In fact, radioactive substances are not only present in the environment but also contained in some of the consumer products we use in our daily lives.

 

One of the well-known examples is a smoke detector. The type that utilizes a radioactive substance is called an ionization smoke detector, and it uses americium. When radiation (alpha rays) is emitted from americium, because alpha rays are slightly charged, a small amount of electric current flows through the circuit. When smoke enters the device, it interrupts the electric current, and this is how smoke is detected.

 

In Japan, due to the regulations regarding the management of radioactive substances, americium is no longer used for household smoke detectors. However, it is still used in many countries, including the US and UK, due to its low price and high sensitivity. Moreover, you will only receive one-thousandth of 1 millisievert of annual radiation exposure by spending time near a detector all day.

 

 

128. Tragedy struck the U.S 50 years ago

Annually, we Japanese people are exposed to approximately 2.1 millisieverts of radiation from various radioactive substances. In fact, radioactive substances are not only present in the environment but also contained in some consumer products used at home.

 

More than 50 years ago, radioactive radium was utilized for the luminous paint on watch dials. Although radium was widely used as a fluorescent material, it caused a social problem, inducing adverse health effects in many workers in American watch factories in the 1920s.

 

At that time, watchmakers licked the tip of their paintbrush before they painted the dials. This resulted in the workers ingesting radium from the tips of the paintbrushes every day. This caused a significantly high level of radiation exposure to bones and led to bone cancer, called osteosarcoma, and cancer of the head. Currently, non-radioactive fluorescent materials are used for watches.

 

This tragic incident promoted the establishment of a predecessor of the current IRPC (International Radiation Protection Commission), an “organization that makes recommendations on radiation protection.”

 

 

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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 18th and 25th June 2017 was reproduced for MRIC Global under the author's permission.

 

 

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