Letters Sent to S.C. Lind, October 8, 1930

October 8th,1930. Dr. S. C. Lind, University of Minnesota, Minneapolis, Minn. Dear Dr. Lind: I have had in mind writing you several times during the past few weeks, but have hesitated to do so as I did not want to appear to be trying to inject myself into a situation which is supposedly being con- ducted by disinterested parties. I refer to the investigation being conducted by the U. S. Department of Health on the employees engaged in the application of lumin- ous material to watch, clock dials, etc. I presume that the final data will be submitted to you for your opinion before it is published, and in this connection I am now taking the liberty of advising you as to the re- action of the clock companies toward the Department's survey, and also the opinions of Dr. Flinn, who has for the past 4 or 5 years been making periodical surveys of the employees of the clock people thruout the Eastern part of the country, especially our clients. We are reliably informed that the clock companies have not been at all well satisfied with the actual work of testing the girls as done by the Department and its representatives. A number of incidents have occurred which have tended to weaken their faith in this survey, most of which we have knowledge of, but presume that you would not be materially interested in. As you realize the matter of electroscopic examination, both by expired air and gamma ray test of individuals for the presence of radio- active materials is a rather specialized problem, and one which, even though we have had several years experience, we still find that upon each examina- tion we learn new things. This work was originally done with my full knowledge, and I may say that together with Dr. Schlundt we probably laid the foundation for the work. Dr. Flinn has materially advanced the technique due to the fact that he has made a large number of tests upon the girls, probably in the neighborhood of 2 to 3000. We are impressed by one or two important facts which I wish to call to your attention: First, we feel that it is highly problematical whether it is possible to determine quantities of less than 1.5 to 2 micro- grams of radium element in a living person by gamma radiation. This is especially true where the tests are being conducted in the field - if the patient were to be examined in the laboratory proporly equipped for making these tests, and the tests could be repeated a number of times on success- ive days, and the results were always constant, I personally feol that quantities of less than 1.5 micrograms could be estimated with a fair degree of accuracy. However, the Department of Public Health tests were all made in the field, and according to what we have heard some of the