Document zbb6NJJN0ge1QgDkXXJ9VdZY6

April 21, X9324. Dr, R, H, Sayers Bureau of Mines Dept* of Commerce Washington, D,G, Dear Dr, Sayer3j X have had a conversation with Dr, Edgar in which he passed on to we your request that X give you my opinion with regard to the possibilities for danger associated with the distribution and handling of gasoline, containing up to 1|.*5 oc* of tetraethyl lead per gallon, with the understanding that such gasoline is to be limited to aeronautical usage* I am glad to state my point of view and to present the evidence on which It la based* The possibilities for danger may be classified under the following headings} (1) those associated with exposure to the prepared gasoline, including skin contact, inhalation of vapors of gasoline under all the conditions of use and spillage} and (2) those associated with exposure to exhaust gases contain!rig finely divided lead, on the part of pilots, passengers and the general public* It seems quite clear to me that we need not concern ourselves with the question suggested under the second heading since the opportunities for exposure to Insufficiently diluted exhaust gases in confined or unvenbllated areas will bo Insignificant in the case of aeroplanes as compared to those which have been afforded by automobiles without evidence of human lead accumulation, therefore there remains only the question of exposure to gasoline containing concentrations of tetraethyl lead up to 1 part In 84G of gasoline* It Is apparent that the vapors rising from tanks or open containers will show slightly Increasing amounts of lead, with increasing concentrations of lead in the gasoline. The vaporised lead in the atmosphere as the result of spillage will also be greater for a given amount of gasoline, with every increase In the concentration of lead In the gaa.l'ne* however, the amountw of lead which will bo present In vapors above tanks are too small to b8 Dr* R* H* layers of practical importance, at the specified concentrations. Moreover, the problem of spillage, with complete evaporation of gasoline and lead is not likely to b of c;nsequence, since the gross amounts of gasoline handled at one place will be relatively small, and since spillage must be guarded against In any case because of fire hazards In view of the complete lack of evidence that lead absorption has occurred from the inhalation of vapors of automobile gasoline under the conditions which exist In garages and filling stations, I cannot conceive of difficulty from a slight increase In the lead concentration of th small fraction of gasoline which is handled under the conditions which exist at air ports* The on factor which must be considered seriously is the influence of lead concentration in gasoline upon th rate of load absorption through the skin of exposed persons* It 1ms been observed that lead is absorbed rapidly out of gasoline through th skin of animals when it is present to the extent of 10 % by volume In gasoline* Absorption 13 very much retarded when the concentration of lead is 1% in gasoline, and it fails to occur when the concentration is Q.l;>. The available data do not justify the plotting of a curve from which the zero point of absorption might be predicted, but the magnitude of the change In absorption which results from the drop from 1G$ to 1% concentration make3 for the probability that absorption ceases at con-* centrationa well above 0.1/1. It does not appear that it would bo hazardous, therefore, from th point of view of 3kin absorption to handle gasoline containing lead in con centrations approximating 1 part in 8I5.O parts of gasoline* Evidence obtained from tho periodic examinations of several man at Wright Field who handled gasoline containing 6 ec* of PbOit)* per gallon toads to substantiate the foregoing conclusion* An interpretation of the variation in the analytical results on these man cannot bo made with accuracy because they were exposed to Ethyl Fluid in the preparation of the gasolines which were being txsed for experimental purposes* Suffice it to say, therefore, that the examinations of fivo men from time to time over a period of three years, during which they war regularly axposod (by inhalation} to Ethyl Fluid, and to gasoline containing b cc* of Pb(Kfc)* per gallon did not result in any symptoms or signs of lead intoxication or evidences of lead absorption* On the last examination of fchoir excreta (19;>2) after three years exposure, th following results were obtained. ME 0009230 3 Subject M.P.C# T.M.L. 5.2. ?.S. P.K. E'.R.L. Pb in Faeces M^s/CcuAsh 0#05 0.05 0.04 0.10 0.08 O.Oi*. Pb in Urine Mgs/blter 0.08 0.08 0.05 0.09 0.05 ; 0.0? The above figures do not demonstrate the occurrence of significant lead absorption. Taking Into account the infer nation no?? aval on the wholo subject or load exposure in relation to loaded gasoline* together with the foregoing observations* which are admittedly meager* I am convinced that the use of lead in aviation field up to lu*> co* per gallon will not be attended by an increased hazard to any group of individuals Vein- truly yours. RAK:TS Robert A* Kehoe, 1I*D* KE 0009231