Document qkakmD7geMQRoLBj0eML9pxz5

January 12, 1962 Mr. Donald Hubbard U.S. Department of Commerce National Bureau of Standards Washington 2b, D.C. Dear Mr. Hubbard: Please accept, my thanks for sending me a reprint of your paper published in the Journal of Applied Physiology. The gentleman who gave you my name was evidently somewhat familiar with our work on the metabolism of lead, and this was the basis of his suggestion. I think, however, that I should point out to you, as I would be pleased to do for him, that the exposure to lead involved in breathing air contaminated with the exhaust gas of automobiles which use leaded gasoline as a fuel is almost too small to measure, and is certainly too insignificant a part of the inevitable exposure to lead of a "normal" man to have any toxic significance. In illustration of this point, we adults ingest about 0.3 mg. of lead daily in an average day, with our food and beverages. A3 city dwellers, we absorb from the air, as much perhaps, as 0.02 mg. per day (the precise quantity is uncertain, but is of that order of magnitude). Part of the atmospheric lead is derived from motor traffic. There are, however, other important sources, such, for example, as the combustion of coal. These facts are amply documented in medical literature to which I can call your attention if you are interested. Cordially yours, Robert A. Kehoe, M. D RAK:ss P.S. You may be intrigued by the coincidence that one of the members of our staff - also a chemist - is named Donald Hubbard. R.A.K