Document wqj6483b4o1vEDBGLqE8X9mJ3

March 7, 1940 Mr. C. H. Cha3, Secretary-Manager Washington State Apple Commission Wenatchee, Washington. Dear Major Chase: This morning I spent neerly two hours with Dr. Kchce. He gave me a copy of a paper soon to he published which summarises his latest work bearing on the lead tolerance question, and I am inclosing it. He stated as a generalization that on the basis of results to date, he has no answers capable of practical application to the immediate problem. Dr. Kehoe would be extremely dubious as to the advisability of a further raising of the lead tolerance at least until there is conclusive evidence as to the nature of lead poisoning itself. The material inclosed outlines a study now in progress in wnich lie establishes that the body sets up an equilibrium between intake and output of lead when larger quantities of lead are ingested over a period of time. The issue is, doss lead poisoning result from 1. Such an equilibrium adjusted to such a high level of lead that the blood stream itself becomes toxic, or, 2. An overthrow of this equilibrium when the intake of lead exceeds a certain critical amount. In other xvords, it is not known what takes place when lead poisoning occurs; there is no explanation yet as to the physiologic mechanisms involved. Dr. Kehos placed great importance on this question. He pointed out his viev? is necessarily somewhat different from that of the Public Health Service; what it must do is to try to adapt itself to the urgency of an immediate situation, while the purely scientific point of view taken by him must depend on complete factual evidence covering every point involved In the matter. He made the statement, "No person knows, and no combination of persons know, what the tolerance should be on the basis of fact." I hope this conveys the gist of what he said without doing too much violence to its accuracy. Sincerely yours,