Document EdB1zqaqq7oY9yKXmBjb08x2j

July 1st, 1936 V Mr. E. G. Phillips 1108 Mercantile Building Rochester, Hew York Dear Hr. Phillips* I am very glad indeed to he able to 3end you by separate cover a series of articles which give the major results of our experimental work in the field of lead absorption and excretion, fl wish to make sure that I did not previously send you a copy of the thick booklet 0n the Normal Absorption and Excretion of Lead ttetc. My supply of these books is exhausted with the on that I am sending you. As a matter of fact I have had to dig this copy up in the laboratory and take it away from one of my associates,on my promise to supply him with another from some source.) The two articles which have to do with the hazards associated with the use of leaded gasoline will be of interest to you chiefly because they give moot of the charts in full in our s tudy of normal sub jocts I think you will find these of some interest, therefore, in that they supplement very materially our other work on normal lead. You are quite right in assuming that I have an opinion as to the maximal levels of lead intoxication. For lead in the air in a finely divided form,I should regard a concentration sbmewhere between 1*5 and 2 mgs. per 10 cubic millimeters as about the threshold of dangerous lead absorption. Below this level I should not expect to find oases of lead #75 3,intoxication. This concentration ia approximately equivalent to a lead inhalation of to mgs* per working day, Under these conditions there would be a heightened lead excretion. As to lead Ingestion, the figure wo\ild be somewhat greater but I should regard it as only doubtfully safe to take In lead by ingestion in quantities greater than a milligram per day# This statement requires a word of ex* planation* I do not feel that we can safely adapt the facts obtained from studies of actual exposure to the entire com munity. One pre-aupposes that there are certain risks in industry of which the workman is aware, and which he accepts as a part of his occupation* It is not to be supposed that the casual citizen can be expected to take any corresponding risk in relation to the basic conditions of his life. (Incidentally any gross increase in the basic level of load ingestion would alter the situation in industry.) A3 I pointed out in my discussion the other day, the present level of lead N9739 Mr. R. G. Phillips Ingestion is,on the average,: a quarter of a milligram per day, This does not result In progressive lead accumulation. On the other hand it is associated with the presence In the tissues of the normal adult of something more than a hundred mgs, of lead, I should gravely question the safety of multiplying this figure by if. Ho one knows how much lead would be found in the tissues of persons who ingest a milligram of lead per day over a long period* Undoubtedly the quantity in the tissues would be increased, and it is probable that the increase would be considerably less than proportional to the increased ingestion. On the other hand, no one could contemplate such a wholesale experiment on a community and be able to 3leep well at night. This is a que^; ion which one does not dare push too much on the basis of opinion* vie must face the facts, I feel certain enough of the facts that I should be willing myself (I leifeg a reasonably healthy, well behaved individual), to ingest a milligram of lead per day over a period of months, 1 should not expect to bo injured by it in any way, and I should expect by the ond of three of If months to have developed an equilibrium after which I would excrete an amount equivalent to that taken in. Under these conditions I wDul^gspect my gross lead absorption to`be considerably less than what it Is at present vihan I am taking in about a quarter of a milligram per day. In fact, I am quite confident that the major portion of this ingested lead would go through the alimentary tract unabsorbed. I think this on the basis of experimental observations. On the other hand, it must be recognized that there are a large nunber of infants, children and sick people whose behavior can not be predicted with suf ficient accuracy to justify any type of experimentation with their health. This is the problem which the apple industry has to face* X repeat what I have tried to put over to them, that the situation in Industry is a totally different one in principle. In reply to your last question, I have administered lead to only two experimental subjects over a short period of 'time for the purpose of seeing how much was absorbed in that short time and how quickly and how extensively the urinary excretion responded* This lead was administered in solution (as lead chLorid^ on an empty stomach in the hope of getting the maximal alimentary absorption* Most of the lead under these conditions runs through the alimentary tract unabsorbed In spite of the most favorable conditions for ab sorption* (It is possible, of course, that the lead compound would have remained longer with the alimentary tract if it had been mixed with food, but on the other hand, there would probably have been a greater interference with the absorption.) I hope you will find the article which I am sending you to be of some Interest, and if I can answer any further questions, do not hesitate to rlise them. Mr, R. G* Phillips RAKjis ''ifch kindest personal regards, Cordially yours, Robert' '.' Keh'oe, M,D R E 0008320