Document 6RODomN0jLzY13xnzZ4DbbNQ3

January 12, 1362 R. E. Eckardt, M.D., Director Esso Research and Engineering Company Medicai Research Division P.O, Box 45 Linden, N.J. Dear Eckardt: In the matter of lead intoxication in cattle there is not as much information as might be desired. The information with respect to the pattern of the toxic response, which would be useful in the recognition of such illness is especially scanty. It appears that these animals do not suffer from a form of intoxication similar to that of man. While this is not remarkable in view of the fact that few of our laboratory animals develop the so called chronic type of lead poisoning, it is not certain that this is not an ex pression of faulty observation with respect to the course of the disease. There is little doubt, however, that farm animals including cattle have sickened, refused to eat, lost weight and sometimes have ( died. The diagnosis has been made on presumptive evidence, as a rule, suppiemented^by analytical data derived principally from the tissues after death. There are few reliable data from which one could make a sound judgment as to the meaning of the concentration found in specific organs or in the tissues generally. No doubt the facts could be established in such a way as to provide satisfactory evidence of this type, but so far as I know this has not been done. Feeding experiments have been carried out with calves and adult cattle in such a manner as to define roughly the ranges of oral dosage (rates of ingestion) which are compatible with freedom from illness (or at least with survival) or production of fatal intoxication. I attach a few notations which I assembled recently from a hasty examination qf soiae of the published observations in response to a question which came from another source. I am not in position to say that this is the best information which is available from any source. However, a fajirly comprehensive review of the literature by one of the members of our staff! only a few years ago failed to turn up any more definitive evidence than this. In considering the problem of the ingestion of toxic substances by cattle and other ruminants, one must reckon with the fact that f( JEf 00 i 5 35 5 R. E. Eckardt, M.D 2 January 12, 1962 alimentary absorption is greatly facilitated by the prolongation of the period required to traverse the alimentary tract, and by the almost complete disintegration of the cellulose constituents in the diet. As to the rate of excretion of metallic compounds by cattle in relation to toxic levels of dosage, there is no useful information, so far as 1 know. Therefore little purpose would be served by the collection and analysis of urine, unless one were prepared to gather eata under varied conditions, to establish, or at least to suggest, their significance. Analyses>of the tissues of deceased animals would be somewhat more useful if the results were widely divergent from the normal range of the finding in the tissues of various other species of animals, The lead content of bones (such as the rib which is readily obtainable) ajid liver, would be especially revealing. No doubt, blood obtained by venepuncture would be the best source Of information concerning the status of living cattle. Sincerely yours RAK:ss Robert A. Kehoe, M. D Vsli 0015356