Document Emx6j4xYND34zE3qBNzaX0xYL

THE JOHNS HOPKINS UNIVERSITY S c h o o l O f H y g ie n e A n d p u b l ic H e a l t h 615 NORTH WOLFE STREET BALTIMORE. MARYLAND D e p a r t m e n t o f B io c h e m is t r y 'V hily 3R, 1933 Dr. Robert A. Kehoe College of Medicine University of Cincinnati C ine innat i , 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 Mr. Cholak are using in the spectrographic de termination of lead. I deeply regiet 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 -purpose of our note in the Bulletin was to indi cate that there was on 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 u n 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 ip the distilled sulfuric acid, or a slight trace of lead in the' graphite electrodes used. In view of thse 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. V/e had insufficient data to make a conclusion upon this point; so our results cannot at a.ll be considered a refutation of your work on "normal lead". Since v/e 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 0020109 K s JOHNS HOPKINS UNIVERSITY c h o o l O f H y g i e n e A n ,d P u b ,l i H e a l t h 615 NORTH WOLFE STREET BALTIMORE* MARYLAND The question thus- becomes- quantitative rather than qualitative. Dr. hxtehie, of Baiiscii-and Bomb, recently told me that he could detect a faint lead line in his spectrograms of blood. I .believe that 'Dutoit arid Zbinden, in Switzerland, reported that they could slv/eys detect lead .when concentration methods were used before photographing the.--a-sb. Our results here , which -are certainly . not extensive,, suggest that a- definite !line1:might be-brought- out. even under great precautions to avoid contamination or intro- . duction'of impurity through the electrodes. As indicated in our note, we used the. lines 4057.83 A..U. , 3583.47, and 3639.58 as raies. ultimes, with the intensities de creasing in the order given. M t c h i e , however, said that he used 2033.-- as his most sensitive line. Dr. Hoag, of the research laboratories of the American Can Co., also considered 2833 as the most sensitive, although upon examination of his plates, he was unable to state definitely that it was more sensitive than the 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 ultiine and of the highest intensity, from comparison spectra that I have made, it appears that under the conditions that I. operate the arc and with the Hilger 31 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 y o u .that we shall be glad to give you any further inform' tion that you may request. If you have them available,. I should lime very, much- to have reprints of your many -publications on igpc, and lead poisoning. Very truly yours, K& 0020 10