Document aQNgE9YRG94vBZpYZ5w9N4dN

January 14, 1957 Dr. W. P. Pelz 1504 East Clark Street. Charles City, Iowa Dear Doctor Pelz: I I apologize humbly for the long delays that have characterized my correspondence with you. i can only ask for your indulgence. Perhaps some return for your patience may be found in the advice which is contained in this response to your last letter of January fifth. I believe that you will find your efforts to investigate the relationship of tetraethyl lead to lung cancer to be wholly unproductive, and I suggest that you turn your interest in this highly significant problem of public health in some more potentially productive direction. My reason for thi3 opinion may be expressed briefly, and I hope, beneficially. First, is the fact that tio significant proportion of our population is exposed to tetraethyl lead. Only persons engaged in the manufacture and the handling of the concentrated material are subjected to such exposure in more than theoretical traces. {C the effects of such expo sure, .more will be said later.) Tetraethyl load in automobile and aeronautical fuels is burned to inorganic lead compounds, and it is not possible to find tetraethyl lead as such in the atmosphere cf urban centers in which traffic is dense. It is there, theoretically, only at times and under circumstances in which the combustion of the fuel is poor - in starting up a cold motor, for example, a little tetraethyl lead in the unburned gasoline. Second, in Mexico, as in the U. S.A., a fairly large proportion, of the gasoline contains tetraetriyl lead, and the environmental conditions there are, in this respect, comparable to those in the U.S.A. Third, is the fact that many thousands of persons ha^e been subjected to the inhalation of inorganic compounds of lead for many generations. Instead of an association of this exposure with a relatively high incidence of lung cancer, the statistics, which, admittedly, are inadequate, suggest that exposure to, and absorption of, lead, tends to inhibit rather than to induce or accellerate, cancer. On this basis, unsatisfactory as it may be, /(')' 0009326 Dr. W. P. Pelz - (2) - January 14, 1957 investigators, and, mo3t recently, Blair Bell and his associates in Liverpool used lead compounds, over some considerable period, in the therapy of malignant disease. They accomplished no very useful purpose, but they were encouraged to continue their work even after there seemed to be scanty hope of success, by a few instances in which tumors regressed. Fourth, several thousand persons have been engaged in.the manufacture of tetraethyl lead since 1923, the numbers having grown more or less steadily 3ince 1926. The nmdical supervision of these men has been more comprehensive than that provided for any other group of industrial employees over any such period of time, so far as my experience goes. Within this group, whose respiratory exposure to tetraethyl lead has been the greatest and most continuous in all human experience, has been utterly insignificant from the aspect of malignant disease, including pulmonary cancer. This represents my criticism of your experimental hypothesis, because of it, I STiggest that you may consider the -advisability of working with some c-ther material. Ivly criticism has nothing to do with my willingness to see that you are provided with a modest quantity of -tetraethyl lead. I art. merely trying to head off what seems to me to be unprofitable uses of a dangerous material, so as to aid in the limitation of its use to productive purposes. Sincerely yours, RAK ef Robert A, Kehoe, M. D. 0009827