Author: Masaharu Tsubokura
Editors: Akihiko Ozaki M.D., Yuki Senoo
185. Accumulation of knowledge concerning radiation protection
Since the discovery of X-rays by Dr. Rontgen at the end of the 19th century, significant advances were made in radiation technology. In the meantime, knowledge concerning the effects of radiation on the human body also gradually accumulated. A report regarding X-ray dermatitis was published in 1896, the same year as Dr. Becquerel’s discovery of radiation from uranium. Furthermore, the association between radiation, skin cancer and leukemia was first reported in the early 20th century.
Also noted in the 1920s were radiation exposure and related adverse health effects of factory workers at watch factories caused by licking the paintbrushes used to paint watch dials with radioluminescent paint. This raised public concern in the U.S.
In this milieu, the International X-ray and Radium Protection Committee was established at an international conference held in Stockholm in 1928. The committee formulates international standards, such as setting the dose limits of radiation exposure to ensure that the level of radiation received falls below threshold level.
Initially, the committee was established for the purpose of regulating radiation exposure levels of workers who handled radiation. However, after World War II, the committee began to discuss regulations to protect the general public from radiation exposure.
After World War II, the committee was renamed the International Commission on Radiological Protection (ICRP), and their announcements are known to be authoritative and critical in radiation protection around the world. Moreover, the regulations established by the committee were adopted as national standards for radiation protection in many countries.
186. Limitation of radiation exposure doses
Since the discovery of X-rays by Dr. Rontgen at the end of the 19th century, the international committee has determined the standards regarding radiation protection, such as the upper limit of radiation exposure, one by one.
Attempts to control and prevent excessive levels of radiation exposure of workers who handle X-rays and radium began about 90 years ago. At that time, the standards were dozens of times lighter compared to current ones. The committee has revised the standards many times up to the present day, and they gradually became much more strict.
Currently, the dose limit for radiation workers is set to a total of 100 millisieverts over 5 years (20 millisieverts annually). Furthermore, the standards specify that exposure is not to exceed 50 millisieverts in any one year. The dose limits for radiation workers are set one or two orders of magnitude higher than the level of radiation exposure other people encounter in everyday life.
Unfortunately, risk of death, such as due to an accident, always exists to a certain extent in any kind of job. The establishment of the dose limit for radiation exposure was aimed at eliminating disparities in the risk of death among radiation workers and people with other occupations.
The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 29nd July and 5th August 2018 was reproduced for MRIC Global under the author's permission.