Document JDaXEr6VBZoapz1ayarkVm56

Dr. L. E. Hamlin. -2- March 28, 1945 6. Another group of 50 guinea pigs would be similarly Infected with attenuated tuberole bacilli and at successive intervals there after while their tubercles were healing, subgroups would be placed in the dusting room to discover whether the burner dust like pure quartz would cause reactivation and spread of the infection. The same infection controls used for group 5 would serve with group 6. In order to oarry out these tests it will be necessary to pro cure several hundred pounds of dust so that a sample of uniform composi tion may be available for the entire exposure period. The exact quantity necessary can only be estimated after we have experimented and determined the behavior of this material in atmospheric suspension, its settling rate and other characteristics. The total duration of the inhalation experiments would likewise depend upon the rate of development of disease. It seems highly pro bable that at the end of one year there should be some indication of the nature of the results but perhaps this will require two years. A third year may be necessary to develop changes in the lungs which are dense enough to cast shadows on an X-ray film. The Saranac Laboratory will undertake this program of research for the sum of $6,000 annually for the first two years and for $4,500 ' for a third year if such proves essential. Preliminary injection tests could be started in June and by September we should have raised a sufficient .number of animals, free from taint of extraneous infection to begin the inhalation program. No time would be saved by purchasing animals from outside sources as these in variably harbor latent infections of the lungs which reactivate on exposure to dust. In the interim the physical characteristics of the burner dust in atmospheric suspension oan be established and the pre liminary injection tests will have developed tsb guide the later parts of the program. It was Indeed a pleasure to have seen you in Chicago and I only regret that my time was so occupied that I could not review with you the films of your employed group. Sincerely, Tsr"- Leroy U. Gardner, M. D Director LUGtRH SPNY 000456