To: Dave Ratcliffe
Subject: The following article is available for distribution in any medium
Date: Thu, 29 Jan 1998 12:54:00 +0900
The Greatest Health Tragedy (SCANDAL)
Ever To Hit Japan
Using United States Federal Aviation Authority actuarial calculation methods, it is shown that over 1 in 70 Japanese workers will be killed by cancer induced by radiation during their company health checks in a nationwide program which subjects them to the equivalent of over 2000 chest x-rays - more than the average dose received by survivors of the Hiroshima and Nagasaki experiments.
Recently I was asked to take a barium meal esophagram, also known as a "barium swallow" or gastric fluoroscopy. I refused after I enquired about the intensity and dose. After a long delay, and the worrying statement that the radiologist had to consult a book, I was told it would be 15 millisieverts. I was told that many Japanese companies regard gastric fluoroscopy with this, or even higher doses, as a standard early detection test, which is repeated annually or biannually.
This means that Japanese workers will be exposed to more radiation than the survivors of the Hiroshima and Nagasaki tests, who received an average dose of 200 millisieverts.
The single fluoroscopy is equivalent to 150 chest x-rays, and 15 times the yearly maximum exposure allowed in the United States. It greatly exceeds the dose received by workers at high level nuclear plants. It is equal to the exposure received by an astronaut in space for one month (recognized hazard). But the energy is delivered to the most vulnerable organs of the body in just a few minutes.
There is no threshold for damage by ionizing radiation. This is admitted by all scientists, although some argue about the repair tolerance. Some make a subjective judgement about what level is "harmless". The damage done by radiation depends on how much is absorbed, and the dose rate. During a barium swallow more ion pairs are generated than the total number of enzyme molecules in the body, making adverse chemical reactions extremely likely. The issue of intensity is often overlooked.
I have not so far encountered a health professional who would allow themselves to be subjected to 15 millisieverts in just a few minutes every year or so. A US professor of medical physics was horrified when told of this practice.
Barium meal esophagrams are not recognized internationally as routine health checks. They are confined to cases where there is a need for pre-operational information for a serious problem. In such cases the radiation hazard is explained to the patient.
I understand that in Japan the current incidence of stomach cancer is about 60 per 100,000. These cancers usually develop late in life.
My calculations, based on the United States Federal Aviation Authority recommendations, indicate that a single barium meal radiation is expected to generate over 90 fatal cancers per 100,000. Fifteen exposures (equivalent to 2250 chest x-rays) causes over 1400 fatal cancers per 100,000. Thus over their working lives, Japanese workers will get more than 20 times the normal rate of stomach cancer.
From Hiroshima and Nagasaki, we know the induction time is about 30 years. That is, the peak in radiation induced deaths appeared in the 1970s. The current barium swallows will cause maximum deaths around the year 2015 with a rising incidence until then. So most victims will appear healthy until after they retire, then develop cancer and die.
Estimation of excess deaths due to X-ray exposure
Using the United States Federal Aviation Authority figures for excess deaths of aircraft crew members due to exposure to galactic radiation in their work, it is possible to estimate the increase in deaths due to fatal cancers caused by health checks.
Assume a risk coefficient of 6.3 (identical to air crew). Assume exposure to 15 millisieverts every two years. After only one exposure, the excess deaths per 100,000 workers is:
6.3 X 15 = 94.5 deaths
For a worker who has been employed 30 years (15 exposures) the result is
6.3 X 15 X 15 = 1427 deaths
Cancer Induction By X-Rays
When the whole body is exposed to ionizing radiation, the organs which are most likely to develop fatal cancers are listed below, together with the relative probability for each one.
Tissue or organ % of fatal cancers Stomach 22 Lung 17 Colon 17 Esophagus 6 Bladder 6 Breast 4 Other 38
However the barium meal swallow fluoroscopy concentrates the X-ray energy into the abdomen, so that the most susceptible organs listed above receive enhanced doses. We can definitely expect the actual distribution of fatal cancers induced by the swallows to be different to the above list. It is known that young women are particularly susceptible to induced breast cancer. But that's a subject which requires another article in its own right.
For esophagrams, so-called "soft" x-rays are deliberately chosen because they are absorbed more (that is do more damage) than the high energy x-rays used to look at broken bones.
On the basis of caution (duty of care), I believe that routine barium meals must be stopped immediately in Japan and a proper study commenced of the mortality of company workers. Company records of dose could provide an excellent basis for research. Every employee has the right to refuse to take the barium meal X-ray. But social conditioning means that the Japanese can not bring themselves to question the medical profession.
Dr Geoff Pain
Century Manor 201
114 Takinoue, Naka-ku
Tel/Fax 81 45 622 6622
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