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October 24, 1942 Col. 0. F. Dorlot, Development and Research Branch, Office of the Quartermaster General, Washington, D. C. - Dear Col. Dorlot* At the request of Mr. C. H. Rasmussen vlth vhom I talked over certain problems connected vlth the use of the Army Field Stove, I am vrlting to you to define in practical terms the lead hazards associated vlth the use of leaded gasoline In cook*stoves. . It has been suggested that the operation of such stoves without any filter for the removal of the lead might be attended vlth little danger over short periods of time, and that field condi tions might veil justify the risks associated vith a lead expo* sure of this type and degree. On the opposite side it has been feared that even in the presence of a filter of average efficiency, enough lead would pass into the air to cause prompt lead intoxication on the part of exposed persons Indeed, av recent article in War Medicine for May 1942 (Vol 2, page 450) by Abraham and Baird at Dale Mabry Field Tallahasse, describes two cases of alleged lead poisoning in persons so exposed. (The clinical background of these cases vas not suggestive of lead poisoning and the analyti cal data on which the diagnosis vas based were fantastic.) Actually both ideas as expressed above are extreme viewpoints. Ho doubt a reasonable middle ground can be found, based on the facts and upon a sensible consideration of such risks In wartime. A concentration of 1.5 rag. Pb per 10 cu. in.of respired air, Is the accepted upper limit of safety in human exposure. This con centration relates to exposures that occur dally in relation to onefe occupation, and is based upon the daily inhalation of 10 cu. m . of air (this being the approximate volume of air breathed by a man during an 8-hour working day). Obviously, exposures involving a shorter period of time could be endured with safety at higher levels of concentration, and intermittent or irregular exposures could be considerably higher. Roughly, a safe concentration can be calculated on the basis of the time of exposure per week, taking 48 hours as the standard for Which the 1. 5 mg. per 10 cum. was expressed. Thus, for example, a concentration of 6 mg. per 10 cu. m. might be regarded as safe for practical purposes for 12 hours of exposure per week. KE 00086i6 Col. G. P. Doriot - (2) - October 24, 1942. The "safe" concentration also refers to prolonged exposure In the sense of months but probably mot for many years uninteruptedly. Any exposure that Is to last but for a short time - l.e. a few veeks or months, may veil be considerably higher. For this rea son, in emergencies and for short periods, much more severe expo sures up to 10 , 15 , or even 20 mg. per 10 cu. m. can be tolerated vith but little danger. On this background ve can consider the facts vith reference to the field army stove vithout a filter* Assuming that the gasoline contains 4 ml. of lead tetraethyl per gallon T4.24 gm. of Pb) and that the stove operates vith a normal stream of air, the effluent stream from the burner (unfiltered) vill contain about 101 mg. Pb per 10 cu. a., disregarding the de position of 1/ 10 to 1/ 8 of this amount in the burners and other parts of the stove. It may be seen to vhat extent this should be diluted by additional ventilation to provide safety for prolonged exposure. The matter can be stated otherwise. We have calculated that gaso line containing 0.06 gm. Pb per gallon could be used vith complete safety vithout filtration. Alloving something for natural venti lation and something for the intermittency of the exposure in a field army kitchen, one vould not expect five times this concentra tion to cause difficulty in a short time, (a fev weeks). If in addition the fumes from the burners were carried avay by a flue, and if full and free ventilation were available, little difficulty could be anticipated vith ten times the minimal concentration e.g. 10 0.06 or 0.6 gm. Pb per gallon, equivalent to 0 .58 c.c. lead tetruetbyl per gallon of gasoline. Of course, food of any kind coming in contact vith the flame or the direct heat of the burner would be contaminated, and such con tamination vould have to be avoidedby suitable methods of cooking. That is, boiling and roasting meats^a covered container would have to supplant broiling. Moreover containers would have to be cleaned carefully on the outside and by methods that would prevent con tamination of other foods. This could be done with little diffi culty if the kitchen personnel were properly Instructed. In this matter of contamination of food, one must recognise that the dan ger of being poisoned Is not so great as that involved in the In halation of vapors and fumes of lead. Lead compounds, even in solution are poorly absorbed from the alimentary tract. Careful observations have shown that not more than one tenth of that which is swallowed (as a solution) is absorbed, and therefore, quantities of several milligrams per day can be taken by mouth regularly for months vithout danger. Continuous accumulation of lead occurs in KE 0009617 \ 5Col. G. P. Doriot - ( ) - October 24, 1942* the body, hovever, If the quantities ingested daily are tm cess of half a milligram of lead, or there boats, and therefore, the ingestion of larger quantities may not oontlnes indefinitely. It appears from discussion of the present problem of the field army stove, that its operation could be greatly simplified to dispense vith some of the more serious difficulties, by means that vould remove a considerable proportion of the lead but not all of it. If this step could be accomplished at once, it appears that considerable relief vould be given to field forces vho are laboring under serious difficulties, vithout incurring any serious danger. Subsequent vork, no doubt, vill result in improvements that will eliminate all the difficulties. It Is my impression from the available information that there is need for immediate action and it is the purpose of this letter to shov that the lead hazards arising out of the use of leaded fuel are not as great as they might be regarded at first glance.- I hope these necessarily voluminous comments vill bo of use to you in connection vith recommendations that are to be made as a basis for present action. If I can be of further assistance in dealing vith this problem, I shall expect you to call upon me. Very truly yours, RAK ef l?oBer"ir.'"^eKoe, l i l n$T Kg 0009618