I read the study by Choi et al.1 with interest, which evaluated the impact of radiation exposure on functional dyspepsia (FD) and IBS. I think the author tried to evaluate the harmful effect of radiation exposure on gastrointestinal function, so they chose a subject that was expected to have the highest radiation exposure among medical workers or the general population. In practice, because of the long latent period and cumulative effect of radiation and various radiosensitivities of different human tissues and because we do not know the exact minimum level of radiation exposure that can cause functional or structural abnormalities in the human body, the International Commission on Radiological Protection recommends a much lower dose than the alleged harmful dose of radiation exposure. For example, <1.0 mSv/year of radiation exposure for the general population and <50 mSv/year and 100 mSv/5 years for radiation workers.2 This means that the dose of exposed radiation in this study subject was at a safe and acceptable level. Additionally, we can approach a similar conclusion from the fact that each abdominal CT exposed the subject to approximately 10.0 mSv radiation exposure3,4 and that in ordinary conditions, no one shows any radiation-related complications.
We currently consider visceral hypersensitivity-central and peripheral sensitization-and psychoneuroimmune interaction were important pathophysiological factors of functional gastrointestinal diseases such as FD and IBS.5,6 This is all about neurons, one of the most radio-resistant human tissues.
Because of these facts and ethical issues, it is impossible to study the effect of radiation on human health. Most human studies related to radiation exposure were based on several historical event in the 21st century such as the atomic bombings of Hiroshima and Nagasaki in World War II and the Chernobyl disaster. From these events, although exact doses are unknown, most people believe that radiation exposure is harmful to the human body.
The author evaluated the psychological stress level and established that a high stress level was related to FD. Although there was no statistical significance among groups, the FD and IBS groups included more shift workers who slept poorly and engaged in less regular exercise and an inferior diet than the average study subjects. This finding suggests that psychological stress and lifestyle are more important than radiation exposure for subjects with FD and IBS with acceptable doses of radiation exposure.
Fortunately (but unfortunately for the investigator), most countries strictly control radiation exposure. As a result, the maximum dose of radiation exposure cannot induce any physiologic damage to our body. As we saw in the results and conclusion, it is almost impossible to obtain positive findings (results) or obvious changes in the gastrointestinal system induced by radiation exposure in well-controlled conditions. Perhaps a much longer follow-up period is required. Therefore, in practice, these kinds of studies have an unavoidable fatal limitation. Even if it showed a negative conclusion, the theme of this study was never investigated before, so it was unique and valuable. Based on this study, I carefully propose a subsequent study with another high radiation exposure group such as health-screening examinees who regularly perform tests such as CT, PET, and mammography.
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