Part 1. Shoe-Store Fluoroscopy:
Enjoyed by Children Almost Everywhere
Two remarkably interesting papers appeared in the New England Journal of Medicine, back to back, in September 1949. We might have anticipated them without surprise in 1929, or in 1939. But they appeared in 1949. Both are well-written and impart quite useful information --- albeit a little late, which is no fault of the authors of the papers.
The first paper is by Charles R. Williams, Ph.D., and is entitled, "Radiation Exposures from the Use of Shoe-Fitting Fluoroscopes." We cite the first paragraph of this paper:
"It is now common practice in many shoe stores and shoe departments of department stores to supplement usual shoe-fitting methods by the use of fluoroscopes known as `x-ray shoe fitters.' Because this technic has spread rapidly throughout the United States, particularly in stores specializing in children's shoes, it is desirable to know precisely the exposures to irradiation received by customers, as well as by clerks and other persons in the area of x-ray shoe-fitting units." We note that the machines were "particularly in stores specializing in children's shoes."
I recollect having used these "x-ray shoe fitters" during my childhood which was mostly before 1930, in Cleveland, Ohio. The shoe-fitter is a vivid childhood memory for countless people. And when did the shoe-fitter infiltrate small-town America? I learned by casual inquiries that it was present before 1930 even in some small towns. Yet only in 1949 did it become "desirable" to learn something about the radiation doses which it was delivering.
It says a lot about the powerful wish for new technologies to be harmless, that the machine was widely spread throughout the United States before any attention was given to doses received by children, parents, shoe-store personnel, and non-participating customers. Did no one care any earlier about making some measurements, in light of all the warnings about the hazards of fluoroscopy in medical practice? Such warnings from Leddy (1937), Braestrup (1942), Buschke/Parker (1942), and others, are presented in Chapter 31. For example, referring to one model of medical machine which put out 127 Roetgens per minute, Carl Braestrup warned in 1942:
"Such a unit could be classified as a lethal diagnostic weapon, and yet there are many of these still in use."
Dr. Braestrup was talking about certain medical fluoroscopes. As for the shoe-fitting fluoroscopes, at what rate of Roentgens per minute did they operate? Dr. Williams (1949) reports on that, and we will discuss his findings in Part 3. Here, we will just say that, at the high end, Dr. Williams found shoe-fitters with an output of 348 Roentgens per minute. It will become clear, as we continue, how these shoe-fitters delivered some breast-irradiation.
Part 2. For Repeated Exposures, Just Press the Button!
The second paper of 1949 is by Louis Hempelmann, M.D., and is entitled "Potential Dangers in the Uncontrolled Use of Shoe-Fitting Fluoroscopes." Some mothers, seeing that title in 1949, might have said, "And now they tell us?"
Let us look at the concluding (summary) paragraph of Dr. Hempelmann's paper:
"It may be said that the type of radiation injury most likely to result from the unsupervised use of low-voltage fluoroscopes in shoe stores is the malformation of the feet of growing children. Such deformities may occur in the absence of x-ray reactions of the skin. Skin damage of the feet of customers and injury of the blood-forming tissues of store employees are possible consequences of the misuses of the shoe-fitting fluoroscopes. These dangers can be controlled by proper regulation of the use of the machines."
But what, in fact, did regulate use of the machines?
A mother in 1949 might recollect the last time she was in the shoe store with her children, and they were savoring the novelty of examining the bones in their feet as they wiggled their toes. The machine shut itself off after a little while, and all you had to do to start the entire cycle again, was to press a button. And that is exactly what Dr. Williams reported (p.333):
"A push-button automatic timer, which can be set for any predetermined time, is included on most installations. In actual use exposure times have been found to vary from five to forty-five seconds, although twenty seconds appears to be the most popular setting. repeated exposures can be made by releasing and pushing of the button [emphasis in the original]."
Also, we learn from Dr. Williams: "More recent models are equipped with three separate switches providing three different intensities --- one for men, one for women and one for children." That can not represent a serious effort to prevent overuse.
Part 3. Foot-Fitters versus Breast-Fitters: How Lucky We Were
The shoe-fitter machines contained a 50 kilovolt x-ray tube, operating at 3 to 8 milliamperes through a 1-mm aluminum filter. The tube was housed in a case lined with lead or steel and containing a fluorescent screen. The kilovoltage was relatively low compared to many medical machines, so deep tissues were less at risk. However, 50 kv is sufficiently high to produce carcinogenic injuries in breast tissue.
The Doses to Feet
Williams established with a series of measurements on 12 separate units that the dose received by the foot was directly proportional to the time that the fluoroscope operated with each button-press. Measurements were done with a Victoreen Roentgen meter placed inside a shoe which was itself put into the opening for the person's foot.
The range of measured dose-rates is indeed astounding to us --- from 0.5 to 5.8 Roentgens per second. So for a twenty-second exposure ("the most popular setting"), doses ranged from 10 to 116 Roentgens delivered to the feet of the customer (p.333). This, of course, was the exposure for a single fitting experience, with no extra pushes on the actuating button.
Some of these are really very high output machines --- 5.8 Roentgens per second, inside the shoe, means an exposure of 348 Roentgens per minute, as noted in Part 1.
Ostensible Efforts to Control Exposure
Dr. Williams has a section of his paper entitled "Control of Exposure." The four factors identified as important for dosage are (a) output of x-ray tube, (b) thickness and condition of filters, (c) distance, and (d) time of exposure and number of exposures. The latter two are controlled at the store, if at all.
It turns out that there were some recommendations for dose-limitation before the Williams study. Both the American Standards Association (1946) and the New York City Health Department (1948) had specified that "The maximum permissible dose per exposure shall not exceed 2 Roentgens." And New York City required further that "There shall not be more than 3 exposures in one day and not more than a total of 12 exposures in one year."
Dr. Williams indicated his lack of trust, that these standards would accomplish anything, by his statement (p.334):
"The only attempt to enforce this provision is a requirement for posting of signs on the machines stating : `Repeated exposures to x-rays may be harmful. Fluoroscopic examinations for shoe fitting should be limited to no more than 12 in one year' [emphasis in the original]. These signs should measure at least 7 1/2 inches by 4 1/2 inches and should be posted conspicuously."
For New York, the hope was therefore to limit foot exposure to 24 Roentgens per year, or less. But unless the machines delivering 348 Roentgens per minute were actively eradicated, then twelve exposures per year, of 20 seconds each, would actually deliver nearly 1,400 Roentgens in one year to the feet of customers using them.
Elsewhere, according to Dr. Williams, there were also some modest attempts to limit exposures. The Detroit Department of Health (1948) required that the maximum intensity in the beam must not exceed 12 Roentgens per minute, and that the maximum time of exposure must not exceed five seconds. The Massachusetts Division of Occupational Hygiene joined in this recommendation. So the intention was to limit the maximum dose to 1 Roentgen per view.
But were sales clerks going to control the number of views per customer? And what about customers who visited several different stores before each purchase?
Public Education about Radiation
We do not deny the right of adults to harm themselves, and to pay the price, in full knowledge of what they are doing. But was there ever a meaningful effort to provide full knowledge about the shoe-fitters, or about any other aspect of radiation exposure?
Today it is known, thanks mostly to declassified government documents, that powerful segments of the U.S. Government were actively engaged --- starting soon after Hiroshima and Nagasaki --- in suppressing information which might cause the public to worry about radiation. Radiation from bomb-testing fallout. Radiation from certain aspects of military service. Radiation from working in certain defense industries. Radiation from living nearby. Radiation from working in uranium mines. Under the circumstances, it was probably not a favorable time to start teaching the public to worry about radiation from shoe-fitters.
The Smile of Providence
We can say it is indeed fortunate that the risk of radiation-induced cancer is much lower for feet than for breasts. At least female children were not getting something "fitted" which would give the breasts the same dose which their feet were receiving from those very popular machines.
Providence did smile on people in many ways, we think, as we contemplate the complex obstacle-course laid out for people hoping to stay healthy.
Part 4. The Measured Leakage and Scatter of Radiation
Dr. Williams did a thorough job of examining leakage of radiation in all directions and heights from the shoe-fitter's cabinet-wall, at a number of installations. Except for the back aspect of the shoe-fitter --- which refers to the semi-open side into which the feet entered --- all other areas measured between 3 milli-Roentgens per hour and 60 milli-roentgens per hour. All these measurements were taken right next to the cabinet-wall itself. It is worth pointing out that ambient natural radiation is about 10 micro-Roentgens per hour in many U.S. locations, so 60 milli-Roentgens per hour is six thousand times as high as natural background radiation. No one should stay in such a region unnecessarily for any length of time.
Scattered Radiation for Customers and Clerks: 100 mR per Hour
In the shoe-fitter, the x-ray beam travels upward from below the feet, and parts of the beam reach the viewing screen above the feet. But some other parts of the beam change direction, because they are "scattered" by the feet, for instance, and by parts of the interior of the fluoroscope cabinet.
Dr. Williams established that, in the shoe-fitter, the opening for the feet was such that radiation was indeed scattered over about a quarter of 360 degrees in the direction of other parts of the shoe-store. If one drew a circle around the machine, one quarter of the circle would describe a region where serious dose was possible due to radiation scattered out of the foot-opening. Moreover, while much of the scattered radiation traveled at right angles to the direct x-ray beam, some of it traveled upward from the opening. Small children walking around could definitely receive scattered radiation to their chests, and so could clerks and parents who were seated, while attending to other feet.
In a diagram (Williams 1949, Figure 2), areas are shown where customers are having preliminary fitting while seated. Such areas showed scattered radiation even higher than 150 milli-Roentgens per hour. We quote Dr. Williams (p.334):
"Figure 2 shows a typical setup in a shoe store. It should be noted that at many of the seats where customers are given preliminary fittings, an area in which clerks may be working, a total daily dose could be received in one hour of operations by anyone in the area." In those years, "a total daily dose" meant 100 extra milli-Roentgens (mR) per day --- a recommended occupational limit per average day back then.
"It Is Obvious ..." Said Dr. Williams
As a result of making his measurements, Dr. Williams wrote in 1949:
"It is obvious from the data shown in the section on scattered radiation that the back (customer's) side of these units should never be directed toward occupied areas within a radius of 25 feet."
We wonder: In how many stores between 1929-1949, and also after 1949, was it "obvious"? And was the scattered dose even higher from some of the earlier shoe-fitter models than measured by Dr. Williams in 1949?
Part 5. A "Ballpark" Estimate on Possible Breast-Dose from Shoe-Fitters
With respect to breast-cancer induced by the widespread popularity of shoe-fitters, three sets of people in the shoe stores deserve consideration: (a) the female children, (b) the young mothers of such female children, and (c) the female workers. In what kind of "ballpark" might their breast-doses fall?
The Female Children and Their Mothers
Suppose we assume that a female child was seated in a region of the shoe-store where the dose from scattered radiation was 100 milli-Roentgens per hour when the machine was "on." We could estimate that time "on" was one-tenth of an hour in each hour. So, potential dose was really 10 milli-Roentgens per hour, or 0.01 Roentgens per hour. And let us assume the child spent a total of one hour per year in this configuration (based on 3 shoe fittings at 20 minutes of such exposure, each). If we assume that the exposure occurred from front to back, then the conversion from Roentgens to rads would be about 0.693 rads per Roentgen for breasts. Under these assumptions, the extra breast-dose might reach 0.0069 rads for this child, each year, as a "ballpark" estimate.
We do not think that every child would have this experience, and we do not know what fraction did have it. Nor do we know how common it was for children to crowd around the machine for "a look" while other children were using it. And we do not know the duration of the Shoe-Store Saga relative to the entire 1920-1960 period represented in our Master Table. There are many uncertainties. Although we make no entry at all in our Master Table for breast-dose from shoe-fitters, there is no doubt that female children and mothers did experience breast-harm from their excursions to the shoestore.
The Female Clerks
We should not disregard the problem of female clerks, since some of them might present an anterior surface or a lateral surface to the scattered radiation, according to the layout of the store. The scattered radiation would be mostly at a low vertical level, but then clerks do sit on a low stool when fitting shoes. The machines were generally operated at 50 kv, so the breast-dose from anterior exposure would need consideration, but breast-dose from posterior irradiation would have been negligible.
Using the information from Dr. Williams, we can make a "ballpark" estimate of breast-dose for the clerks.
Their exposure in the fitting area could be 800 milli-Roentgens per working day (from Part 4). But since some clerks would have their backs to the source, we reduce the anterior exposure to 400 milli-Roentgens. And because the machines were not putting out x-rays all day long, we estimate (as we did above) that the machines operated only one-tenth of the day, which would reduce breast-dose to 40 milli-Roentgens per day or 0.04 Roentgens per day. After conversion to rads, this would be 0.028 rads per day --- for the stated assumptions.
From 200 days of work per year, the breast-dose could be 5.6 rads per year. For an individual woman, this would be a serious annual dose-rate, but after averaging the exposure over all the women who did not work in shoe-stores, the average dose would be reduced a great deal. For the sake of illustration, a 100-fold reduction would mean an average annual dose of 0.056 rads. If we were making entries in our Master Table, we would need to know the appropriate reduction-factor, as well as how many years the shoe-fitters were widely present.
Although we make no entries at all in our Master Table for breast-dose from shoe-fitter fluoroscopy, we are sure that some female clerks did indeed receive injurious breast irradiation. "No entry" in the Master Table does not mean "no dose."
Part 6. The "Technological Imperative" --- Expose Now, Regret Later?
In Dr. Hempelmann's paper (1949), he stated in several places that there was insufficient information to enable people to predict the effects of using the shoe-store fluoroscopes. For example, he stated (p.336):
"Little is known of the radiation doses that cause chronic skin damage." And: "There is no published information bearing on the maximum radiation dosage that can be administered to the skin with safety at the intervals at which children are likely to be fitted for new shoes (two to four months)."
Did Dr. Hempelmann believe that the current (and prior) usage of the machines was safe? Clearly not. He wrote (p.336):
"To prevent injury to customers and employees, it is obvious that the use of x-ray machines in shoe stores must be controlled. Proper shielding of the fluoroscope to minimize radiation leakage, education of the users and store officials about the dangers involved in misuse of the machines, and reduction of the foot dosage per viewing must be accomplished. Shielding of a low-voltage fluoroscope is a relatively simple matter. Conspicuous warning signs on each machine can help to educate the public to the dangers of too frequent use of fluoroscopy; restriction of the use of x-ray machines to qualified personnel will reduce the possibility of accidental overexposure. Reduction of the foot dosage per exposure can be accomplished by lowering of the tube output, by adequate filtration and by limitation of the exposure by automatic timing devices. Since the maximum amount of radiation that the foot can tolerate at intervals of several months is not known, it seems advisable to reduce the foot dosage to the minimum that is compatible with satisfactory use of the fluoroscope."
This advice is an interesting illustration of the dominance of the technological imperative. Given what Dr. Hempelmann acknowledged was not known about either the skin or the feet (which were the apparent limits of his concern), and given the unrealistic prospects of financing a campaign for "education of the users and store officials" and for "qualified personnel" to operate the shoe-fitter fluoroscope, it seems to us that the one question which deserved consideration was simply not asked: "Who needs it?"
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