Document EvrQ8odpVqvL0KejpaKmGyR4j

THE JOHNS HOPKINS UNIVERSITY Sc h o o l Of Hy g ie n e a n d p u b l ic He a l t h 615 NORTH WOLFE STREET BALTIMORE. MARYLAND Oe p a r t me n t o f Bi o c h e mi s t r y July 28, 1933 Dr. Robert A. Kehoe College of Medicine University of Cincinnati Cincinnati, Ohio Dear Dr. Kehoe: Upon returning this summer to the' lead research, I find that Dr. Shipley has referred to me your letter of June 13, in v,rhich you very Kindly describe for us the technique that you and Ur. Cholak are using in the spectrographic de termination of lead. I deeply regr'et the delay in answering and hope that you will accept my sincere .apologies. It so happens that although we reported last fall on the spectrographic detection of lead in the blood, the pressure of other research of an immediate nature prevented me from continuing the lead work. The problem is only now being re sumed; so I am afraid that our. work is in a. more preliminary stage than yours. however, I shall give you what little inform ation I have available. v. The puroo.se of our note in the Bulletin was to indi cate that there was an easily detectable difference between the amounts of lead found in the blood of lead poisoning cases and of non-lead poisoning eases. We stated that the controls gave either negative results or questionable traces. The un certainty in the statement was intentional, because at.times the controls showed faint lines which could possibly have been caused by slight contamination during handling, a. slight lead content ih the distilled sulfuric acid, or a slight trace of lead in the' graphite electrodes used. In view of these con siderations, we were unable to ascribe certain significance to these faint traces. This does not mean, of course, thatthe lead line could not be brought o\it definitely by other workers, `,7c had insufficient data to make a conclusion upon this point; so our results cannot at all be considered a refutation of your work on "normal lead". Since we all must ingest small amounts of lead from food, and possibly from tobacco and other sources, at any time there should be a certain amount of lead in the blood. K JOHNS H-OPKINS UNIVERSITY rr* s c h o o l Of Hy g ie n e An ,o Pu b l ic He a l t h 615 NORTH WOLFE STREET BALTIMORE* MARYLAND H-eM-l.ST.-RY The question thus become: quantitative rather than qualitative. Dr. hxtchie, of Bausch - and Bomb, recently told m-e that he could detect a faint lead line in his spectno.-gr.aras of Hood. I believe that Dutoit and Zbinden, in Switzerland, reported that they could pIv/ays detect lead when concentration methods were used before photographing the ash. Our results here which are certainly nqt extensivesuggest that a- definite ! line-: .might be-brought- out even undergreat precautions to avoid c ont an inn t i on or-intro-.- due o: iicpurity through the elect ro de s. As indicated in our note, we used the. lines 4057.83 A..U. , 3583.47, and 3639.58 as rales. ultines, with the intensities de creasing in the order given. Hitchie, however, said that he used oqr s his most sensitive line. Dr. Hoag, of the research orato iss of the American Can Co., also considered 2833 as sensitive, although upon examination of his plates, he v/v s nable to state definitely that It was more sensitive than 4- he lines that I first mentioned. Eder and Valent a., in their atlas, list 4057 as the most intense arc line; Hilger pamphlets also list 4057 -as a rale ultime and of the highest intensity. S-rom comparison spec tra that I have made,, it appears that under the conditions that I operate the arc and with the K: Iger El instrument that ,is used, 4057.83 appears more intense than 2833 even in low concentrations. It night be, however, that although 4057 is more intense, 2833 might be more persistent. I hope to determine this soon by means of quantitative standards. Y/e' were very glad to send you a. reprint of the paper on the spectrograph analysis of mi 11c ashes, according to your request. Again I beg your pardon for the unavoidable delay, and assure you.that we shall be glad to give you any further inform ation that you may request. If you have them available,. I should lime very, much to have reprints of your many publications on ig p c . end lead poisoning. Very truly yours. K 0020110