Document NG4qmJgEeroVNJo9zK16eyGkw

January 6, 1938 accept my thanks for a lead In the urine and tissues and excreta* to me and I hope you es which come out on es * ?-e o-->^/V' urs to me that you he work which we have d particularly useful on the study of large on. single' individuals taken at random*. seems no doubt that le people studied by you the American population, ill frankness that I am he degree of variability of results obtained on the urine samples. In our experience the largest single factor which produces gross variation in the urinary lead excretion of a single individual is the water output from day to day* (I refer here, of course, to standard conditions of lead exposure. Thus if the lead intake is substantially the same from day to day, lead output in the urine will vary chiefly with the water output.) In other words the amount of water con sumed is a factor and the amount lost in perspiration is also an important factor. The differences due to this factor will he seen clearly in studies made on subjects under laboratory conditions, as described in one of the articles which I am sending you. This brings me to say that because of your interest in this subject, I am sending you, under separate cover, a number of reprints which describe the results Of some of our studies in this laboratory. Unfortunately some of them were published in journals