Document 4ajyDerzmerp4NjJXajaEyXoa

June 26, 193? Dr, Kenneth D, Blackfan Harvard Medical School Children's Hospital 500 Longwood Avenue Boston, Mass, Dear Doctor Blaekfan 1 X am complying with the further request In your letter of June 22nd hy sending you herewith a reprint of Cbolak's article describing his spectrographla method of lead analysis* We are in the process of preparing an article for publication which will describe the details of the "Dlthiaone method of analysis which we use* As to the methods of Collecting samples* ua have had all stainless steel needles manufactured for us by the Max Woeher and Son Company of Cincinnati, It Is only necessary to specify that the needle be made entirely of stainless steel* And that the hub which is commonly used In the ordinary needle should be completely eliminated* This requires e. special method of fabrication but one which Is not difficult* Obviously these needles are somewhat more expensive than the standard brand* In obtaining blood samples* we prepare pyrex test tubes into which blood and spinal fluid can be drawn* These ere washed carefully with cleaning solution* rinsed repeatedly with distilled water* and then rinsed at least three times more with distilled water*triple distilled from either a pyrex ; or a silloa still* preferably the latter* These tubes 2 are allowed to drain* stoppered with a clean cork which has never been used before* and covered with a clean filter paper which is held in place by a rubber band* The blood spaple is taken dlreotly from the vein into the tube by means of a special need and usually without a syringe* (X occasionally take samples In the laboratory slaking use of a pyrex syringe which has been sterilised by boiling in distilled pater after which It Is rinsed three times with triple plstilled water* as previously mentioned. In general* however* X prefer to let the blood run dlreotly through the needle into the tube*) When we have samples obtained by other doctors* we provide both the blood tube and the needle * The latter la cleaned ap previously described* put into a clean pyrex tube* N21240 Dr. Kenneth D. Bl&ckf&n stoppered with cotton and sterilized In the autoclave so that it la ready for use without any further attempt at sterilisation* After taking the ample, the blood tube is stoppered, the filter paper replaced carefully and the tube la kept In an upright position. If possible, so os to avoid ooataot with the cork* (We have had a number of samples sent to us through the mall In which this latter precaution could not be observed, and we have had no difficulties* However, there Is the possibility of slight error In that the serum might be absorbed to some slight extent into the stopper* Substantially the same technique is observed In the ease of spinal fluid, the needles being prepared and sterilised in advance and the fluid being with* dbawn Into the tube prepared as In the oase of the blood tubes In general, where it is feasible, we obtain a spot sample of urine at the same time the blood Simple it taken* A small pyrex bottle Is prepared in exactly the same manner as the blood tube and the subject Is asked to void approximately 100 oc of urine directly Into the container, after which It Is stoppered with Its glass stopper whlob Is held In place by a filter paper covered securely by a rubber band* We have been able to obtain samples in this fashion even when they have had to be mailed to us from some distance* In general the results are satisfactory although, obviously, better results can be obtained in the laboratory* $h great difficulty in connection with urine samples is that It is almost Impossible to impress people with the necessity of having the sample voided directly into the container. Ordinary hospital equipment, if used as an intermediate container, will so contaminate the sample as to render it utterly useless, and misleading* Consequently in our work here at the General Hospital and the Childrens Hospital, we have Insisted that the internes obtain the samples themselves and make aura that they are collected precisely according to instructions* In general there 1* approximately a ten to one relatlonshlpMn the concentration of lead in the blood as oonpared with the urine* That is to say, the con* centrati on In the blood expressed in terms of 100 grams is approximately the seme as the concentration In the uribe expressed in terms of a liter* Obviously this relationship dotes not hold too closely if if we are able to obtain a bipod cample and a small urine sample on a patient at the same time, and if these samples check so as to have approxi* mately the same physiologic significance* W* fteel that in all f0r, 0 4 443 5 Dr. Kenneth Blaokfan probability neither sample has been seriously contaminated in the process of collection* If the samples do not agree, w feel disposed to Insist upon the collection of additional samples, and with somewhat greater precautions# Moreover we do not attempt tp draw refined conclusions from borderline cases* The lead content of both blood and urine may vary from time to time to such an extent that repeated observations may be necessary in order to give a certain significance* In our experience spot samples of urine taken at different times of the day and on different days are subject to fairly wide variation* Consequently we do not like to draw too strong conclusions from a single spot sample*Where it is feasible, we try to obtain a sample which \ will represent the urinary output over a period of to 72 hours. In such a sample the hour to hour variations will be Ironed out and we have reason to believe that In such a sample ne are dealing with an average secretory condition. 4 lead content In the urine of one tenth of a milligram or more per liter Is obviously significant of a comparatively recent exposure to lead, and if the quantity is In ecess of fcwcNtnths of a milligram per liter, we feed:-certain that we are dealing with significant lead exposure* Kot all persons with this level of lead excretion show symptoms* A very large proportion of persons with symptoms show levels of this order of magnitude* r You will note that I am Inclined to pat much greater faith in the analytical results from more than one source than in a single sample* It is for that reason that X like to have a sample of urine and a sample of blood obtained substantially simultaneously, if this Is possible* t truet X have not indulged in any repetition of my former remarks to you, but X want to be quite clear as to my point of view and the reasons for it. Cordially yours. EAKjis Robert A. tfehoe,""M.D* fa 04444