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llovenber 27, 1944 Dr. U. E. Bowes ' OvenB-Illlnol8 Glass Conpanj Toledo, Ohio Dear Dr. Bowes: It vtsb a pleasure to have had opportunity to dioouco the K-Lo problem with you and Hr. Rirth in Pittsburgh the other doy and an keenly interested in your proposals for further investigation of any hazards uhioh night be associated with exposure to dust of th naterlal. To summarize our discussion I mav state that in ny opinion 6Uoh an investigation, should include (1} an inspection of manufacturing prooesoee st the new plant In Berlin, Rev Jersey7 (2) a study of the behavior of E-Lo duct In atmospheric suspension inclu such features as the effeot of humidity,.tendency to flocculate and settle, the relative proportions of fibres and particles in air floa' dust, etc., and (3) dally exposure of a large nunber of experimental animals to high concentrations of dust of this material to determine first, v/hether it can be inhaled into the lungs in significant quant: and second, whether it will produce serious pathological reaction. On investigation of our .situation here I believe we w,! he in a position to start such a study about January 1, 1945. By tha time we hope to have the neoessary number of guinea pigs and white rc available. For the moment our supply is very limited. Our engineer will plan to visit Berlin, New Jersey ae soon as his schedule will permit and I also shall expect to do so vhe I cd in the vicinity which should not be too far distant. Ve will vs to collect several hundred pounds of duBt in order to insure material of uniform composition for the entire experiment. Probably as you ou gest dust from ths oollector system in your factory would-be eatisfoc for the purpose unless it Bhould be grossly oontanlnated with other d The exact amount that we shall need would have to be determined after ve experiment with it to discover hew. readily It will produce a dust cloud in our experimental room. I would suggest that you send us abo ten poundn of oolleotor dust for preliminary investigation. Ve should oontenplat'e oxpoeing at le*.t 150 guinea pig 50 white hats and perhaps 10 rabbits 8 hours daily 6 days a week over period of one or two years. The nature of the results would determin the duration of the experiment. If the one year results are negativo or minimal it will be neoeBsary to continue the exposure for at le-^-st - y < ' - 'N?* W y  Dr. D. E. Bones -2- Hovenber 27, 19rJ* s another year In order to make certain that this naterlal does npt slowly pe.netrate and accunulote within the lungs to cauBB chronlo tiasue reactions. As in previous experiments this test will involve sacrifice of groups of exposed animals at lntervalo during the exposura; gross nlcroBooplo and chemical cnalyoes of thoir tissues. In view of the faot that there nay he oooe unoonbined cilioa la the mixture I believe that 50 of the guinea pigs with a like number of undusted controlo should be Infected v/lth tubercle bacilli to dip- " cover whether there le any alteration .of susceptibility to such infec tion. The coat of this experiment will be $5,000,00 a year plus tho necessary travel expenses of our en~lneer--far.lolant_ inspection! Should you"dia'irc to undertake it I would suggest that payment be made quarterly to the Saranac Laboratory. You would, of course, supply the n-ocess.Bry dust for Investigation. The Laboratory will beep you Inform? of the'progress of the work and on its completion furnish a complete report of all details of the study. It is hoped that the results cay be cuch that you might wish to have us publish our findings but it is understood that nothing will be published without your authorization. Tery truly yours, LD0:RH oc to Kr. A. C. Hirth Leroy U. Gardner, K. D. Director