Document q38eG69nOQ6Kz0pa0b06jazG

First iold here Professor R A Kehoe, M .D . , .. The Kettering Laboratory, University of Cincinnati, ..... College&-MeUi o-ine-,... Eden Ave, CINCINNATI 4^219, t H.S.A. ^ r - Second fold here --^ Sender*! name jnd jddiru: y\ Dr. H .K . Williams, Department of Occupational Health, London School of Hygiene ft Tropical Medicine, Keppel Street, (Gower Street), LONDON W.C.3. AN AIR I.ETTER SI IOULD NOT CONTAIN ANY ENCLOSURE: IF IT DOES II WILL BE SURCHARGED OR SENT BY ORDINARY MAIL E'orin jfijimvc'il by the Postmaste_*rr General, Nd;'71^95/2J IMPERIAL AIR MAIL AtROtHAMI r ijf iVai-k*' co*bU! tp.^rxirnAiirro h" *13JIIODado0 C\ t-O CD CD January 26, 1966 Dr. M. K. Williams London School of Hygiene and Tropical Medicine Keppel Street LONDON, W.C.l. Dear Doctor Williams: I am impelled to comment on certain of the further queries and views in your letter of January 7; I shall take them in the order oi their occurrence in your letter. First, with reference to the significance of the concentration of lead in the blood, I shall have to say that 1 cannot accept your statement that it is the best index of the exposure to lead(which I shall soeak of as the current level cl' exposure to lead). The rate of the urinary excretion from day to day is by far the best indication. The concentration in the blood, on the other hand, is the best available evidence of the extent of the absorption that has occurred - that is, of the body burden of lead, or the result of the exposure to ieuu over some considerable period of time. It .s clearly not indicative of tne existence of lead poisoning, which, as I have indicated previously, is manifested by a characteristic illness, or a specific interference with a specific interference with function - as, for example a lead-induced disturbance of the porphyrin-hemoglobin metabolism. I wonder why it is that you are loath to label the latter phenomenon as a feature of lead poisoning. I agree that it is not always possible to determine the cause of this phenomenon, or the cause of anemia. However, these are situations in which I would be quite willing, on the probabilities (without actual orooi), to ascribe one or the otner, or both of these, to the effects of lead. Under such circumstances, it is intoxication. Why split semantic hairs? 'excessive lead absorption" has no meaning in clinical medicine, except to indicate that the individual so involved, is in a state of risk. He is not, necessarily, in a state of illness. I abhor confusing words, and this phrase is not only obscure, but has been a shield to hide behind, mecically speaking. On the other hand, the man with lead-caused anemia or lead-induced porphyrinuria is ill. He may not be aware of it, but his physician may be. I think here you are bandying words when you say this is not clinical poisoning, because there is no awareness on the part of the patient, of exceeding the symptomatic threshold. You ire in error, in my experience, in saying that a little lead causes an Increase in porphyrinuria. If one determines the concentration of porphyrins in the urine (this, of course, requires the use of a good quantitative procedure), he will find a sharp cut-off between the results which occur under ordinary conditions and those which are associated with dangerous levels of lead absorption. This, in my view, when other causes of an abnormal concentration of coproporphyrins in the urine can be excluded, is the first clinical (in the sense of a functional disturbance) sign of lead poisoning, and one which should be heeded promptly, lest a more serious form of poisoning should appear. I am prescribing, here, of course, a conservative medical procedure in handling the workmen in a dangerous lead-using industry. This is a bit different, admittedly, from the making of a diagnosis for Dr. U. K. Williams Page 2 January 26, 1966 medico-legal purposes, on a basis that is acceptable, generally, among oadical men. However, this is the way a new diagnostic position is achieved, and this is something quite different from compensable disability due to lead poisoning. But so, for that matter, is the recognition of Impending danger because of a degree of absorption of lead - a danger which requires action on the part of a physician in removing a man from further exposure. We have no mechanism in this country for dealing in compensation law with such cases. Consequently, the employer will make every effort to find a Job for the workmen that is free of lead hazard. In any case, I see no reason for not expecting a knowledgeable physician from exercising Judgment in such cases, as to whether the probabilities are in favor of abnormal effect due to lead. I really don't care whether or not he labels the condition as "lead poisoning,"or "incipient lead poisoning," or "threatened lead poisoning," but I don't take kindly to the term, lead absorption (by itself or modified by an adjective) since this term relates to a general physiological process. It suggests that lead absorption implies some potentially harmful effect of lead, whereas this is basically untrue, and it is high time that we recognize this fact in our speech. One other point requires some clarification. (Please do not think I enjoy being a carping critic. I am merely trying to talk plainly.) You speak of the "release of lead from cells." That is not what I have in mind when I consider the release of lead from a firm or loose chemical bond. I think rather of its release within cells, and the induction of an effect thereby. There is no evidence for this, any more than there is evidence cf an elevation of the lead content of the plasma in acute infections, alcoholic bouts, and disturbances In the acia-base equilibrium of the tissues. But since there is no evidence of the latter group of factors (which you speak of as having been noted in the past), I cannot but suspect that some such subtle biochemical change occurs, without any representation of such change in the peripheral blood. You may be right, of course, about the occurrence of lead poisoning when the concentration of lead in the blood is low. If so its occurrence is rare, for I have never seen such a c^se. The erythrocytes have a very great capacity for taking up lead and virtually depriving the plasma of more than traces. Consequently, I cannot think it very likely that their reduction in number, within moderate limits, will have much effect upon their carriage of the lead that is available through the usual metabolic processes of the body. It is entirely possible that you will react unfavorably to ray comments, although I have found British physicians and scientists to be somewhat less reactive in such matters of discussion and controversy than many of my colleagues in this country. I am encouraged, therefore, to express divergent points of view, without fear of seeming to be excessively opinionated or discourteous. Believe me, I should like to talk with you in person. Cordially yours, RAK:wp Robert A. Kehoe, M.D. S 00579