Document 10JYp3rYdGYV5Ek89LB9G2gxK

Oy REPORT ON THE POTENTIAL HEALTH HAZARD FROM THE USE OF LEADED FUEL IN ARMY FIELD RANGE M-1937 Tune 1, 19^ 1 r v l ^ e ' 000SG3G The Potential Health Hazard from the Use of Leaded Fuel in Army Pield Range M-1937 I. Purpose To determine the magnitude of the health hazard arising from the use of leaded gasoline for fuel in the fire unit. . II. Conclusions (1) No health hazard exists from the breathing of lead in air when the stove is operated in rooms or enclosures under normal conditions of ventilation. The small amounts of lead which escape through the burner may deposit upon cool cooking receptacles or the walls of the stove. The deposits are easily removed and under normal housekeeping conditions no hazard should be created by them. (2) The stove should not be used for the broiling or grilling of foodstuffs that come into direct contact with the flame, III. Introduction (1) Design Complete description of the stove may be obtained from the manual for its use and by reference to reports of the Detroit Laboratory of the Ethyl Gasoline Corporation LTD #4-1-5, 363-XP-2 1 22, and 24-- 2$. Previous experimental work has been carried out on the stove at the Army Medical School and at the Detroit Laboratory of the Ethyl Gasoline Corporation. The tests at the Army Medical School, using gasoline that contained 0.75 ml. of lead tetraethyl (TEL) per gallon, indicated that insignificant amounts of lead escaped into the room air during the operation of the stove. They further found no increase in the lead content 2- of foodstuffs prepared with the unit. Studies carried out at the Detroit Laboratory indicated that about joi of the lead input was removed by the filter disc and other parts of the stove. Neither of the above experiments were carried out in such a manner as to account for all of the lead in the gasoline by examination of lead remaining in the stove and analysis of the flue gases. The following experiments were carried out with that objective in view. ' IV. Procedure Following preliminary operation and adjustment of the fire unit, observations were made on the temperatures at various parts of the stove and fire unit. Following this a sheet metal hood was constructed for the purpose of collecting, measuring and sampling the effluent gas from the stove and to provide for temperature determinations upon it. Details of this equipment are given in Figure 1. The drain at the second ell was found unnecessary as no condensate formed. It was not possible to measure the velocity of the effluent in the lead-off duct by mechanical means and volumes were determined.by sampling the effluent and analyzing it for carbon dioxide, oxygen, and carbon monoxide, using a Burrell gas testing apparatus. Volumes were computed in terms of cubic feet of effluent per gram of carbon. The lead content of the effluent was determined by passing the sample through an electric precipitator of the Cottrell type, at known volumes and temperatures for the sampling period. In addition, a portion of the precipitator exhaust was passed through freshly activated charcoal to determine whether any -3- organic lead vapor was present in the flue gas. All gas volumes were corrected to standard conditions. In computing results, the amounts of carbon monoxide were neglected as the percentages were so small as to have no effect upon the final values. The fuel used for the first runs was an Ethyl Gasoline base stock of the Standard Oil Company of Ohio, mixed in the laboratory to a concentration of 3 ml. of TEL per U.S. gallon. Samples were analyzed for lead content at an Ethyl Gasoline Corporation Laboratory before use in the stove. At the conclusion of several runs, samples for analysis were removed from the stove reservoir as a check on the original results. Lead was recovered from the fire unit according to a definite procedure. The unit was dismantled and the parts brushed and scraped into a clean porcelain dish containing a small amount of 20%> solution of ammonium acetate, after which each part was bathed with hot 20% ammonium acetate followed by hot 5% nitric acid, then with hot distilled water. This treatment effectively removed all deposits which were then combined and analyzed. The filter disc was carefully removed and steeped in hot nitric acid. This destroyed the structure of the disc and permitted complete solution of all filtered material. Following filtration the residue was boiled with 20% ammonium acetate. The filtrate obtained from this treatment was added to the nitric acid filtrate. Hood and chimney scrapings were also dissolved in nitric acid. Analyses were carried out by the lead sulfate or by spectrographic methods and some samples were analyzed by both methods for check purposes. .. KE 0009639 4. In short, therefore, the procedure involved the analysis of gasoline for lead content prior to use, the determination of the lead deposited in various portions of the fire unit, in the filter disc, and on the walls of the hood and chimney as well as that in the effluent, either as vaporized organic or as particulate inorganic lead. 'The totals of the last sets of analyses should equal the first within the limits of allowable f analytical error, duly corrected for the amount of gasoline burned. Thirty-nine runs of approximately 4- hours each were carried out. Complete analytical data, as indicated above, were obtained on runs 1, 2, and 39 When received by us the stove was new and after the first two sets of observations, it was thought desirable to operate the;stove under conditions that would simulate a period of at least a month*s use and to recheck the results of the initial experiments. Runs 3 and 4- as described later, were carried out to determine the behavior and efficiency of the filter immediately after the stove was started up and before the generator and filter had reached operating temperatures. V. Results . (1) Operating temperatures of the stove Referring to Table 1, the figures for the temperature cf the filter case, filter level and at the generator level, are of considerable interest from the point of view of the nature of the deposits on the filter. IP certain instances these figures approach the boiling point of the lead halides that may be expected to be present at the filter. -5 However, the high percentage recovery of lead from the filter, together with the fact, discussed later, that most of the lead escaped from the filter before it reached high temperature, indicates that.the vapor pressure of lead halides in the generator tube had no material effect upon the escape of lead through the filter. (2) Balance Experiments - Runs 1, 2, and 59 Results are given in detail and in summary in the attached tables. The average lead recovery in these three experiments was 96*23$ within the limits of error of the analytidal methods employed. Accordingly, no explanation is offered for the unrecovered lead. Amounts of organic lead recovered from the effluent were insignificant and sampling for organic lead in the flue gas was discontinued after the second run. Considering the fact that a perfect balance was not achieved in any experiment, it should be pointed out that the results varied when duplicate samples of the gasoline were analyzed, the maximum discrepancy being from 2.36 to 315 ml. TEL per gallon. Depending upon which figure was taken for computation of the balance, recoveries varied from 96 to 112$. In this situation we selected the value for lead in gasoline that most closely corresponded with the amounts that had been carefully measured and added to the fuel* . As indicated in the summary, 90 to 96$ of the lead which entered in the gasoline was recovered from the stove and filter* Since the results of the Detroit Laboratory, obtained in using a different stove, showed only 70$ recovery from these sources, it would appear HE 0009041 -6- that either differences in stoves or differences or imperfections in filter discs may greatly affect the amounts of lead retained by the unit. The total amounts of lead recovered from the flue gas were small, the average being less than 4#. It should be noted however, that a variability of as much as 100# in the amounts of lead recovered in the flue gas occurred on two successive runs. Since the stove was operated under identical, conditions each time, the only change being the renewal of the filter disc, it is quite possible that there is significant difference in either the effectiveness or fit of different filter discs. Certainly any channeling, perforation or ,, imperfection of discs would greatly affect the retention of lead. Since there is no way of determining the condition of the disc prior to use other than by inspection, the results of any one run with a bad disc may deviate widely from others# This would however, represent only a maximum 4-hour period of use. ' (3) Initial Period of Operation In runs 3 and 1]-, the results of which are given in the attached tables, samples of flue gas were taken at frequent intervals as soon as feasible after the stove was put in operation (beginning usually within 1 minute). As might be expected, it was found that the efficiency of the filter was least when the generator tube was cool and the filter disc previously unused. Over 75f of the amounts of lead found in the flue gas in the 4-- hour run came over in the first hour and about 70# in the first 30 minutes of operation. From a practical point of view, therefore, it is apparent that if 7- adequate ventilation is provided in the first 30 minutes of operation of the stove, the hazard from contamination of room air will be greatly reduced, not only in this time, but during the subsequent 3**l/2-hour period of operation. This failure on the part of the stove to retain lead in the first 30 minutes of operation is apparently almost entirely due to the low temperature of the generator tube. The TEL not being broken down, passes the filter as vapor and is burned in the flame. To test this, samples of gasoline vapor were collected at a slow rate from the mixing chamber beneath the burner, the vapors condensed at - *Jd|.0 C, and analyzed. :v Because of the length of time necessary to collect sufficient condensate (1 - 3 ml.) for analysis, it was necessary to extend this sampling period over the entire period in which the stove was coming to its operating temperature. Fractional analyses by minutes during the early stages of operation were not feasible. It was found that during this heating up period, the generator was very inefficient as compared to an efficiency of 0 to 5% when the generator tube had become hot and the stove was operating normally. It follows therefore that from 15 to 20$ of the TEL in the fuel is not cracked or broken down in the generator tube or filter case, but passes on to the flame where it is decomposed. In view of possible modifications, such as an increase in the length of the generator tube to bring about more complete decomposition of TEL, It should be pointed out that no change in design other than one that would permit starting the stove with a hot generator tube would alter the behavior of the unit in the first 30 minutes of operation. -g It is in this period that the greater proportion of the lead in the fuel passes through the filter and into the flue gases. 71. Hygienic Considerations As pointed out above, the greatest escape of lead in the flue gas occurs in the first 30 minutes of operation. In Table 2, pertinent data from each of the_experimental runs are tabulated and the lead in the flue gas has been computed in terms of mgm. per 10 cu.m. Amounts of 1.5 mgm. of lead per 10 cu.m, of air or less are considered to be allowable. If we assume that only flue gas is respired, under conditions which permit of no ventilation, inspection of the figures in Table 2 is of , considerable interest in the light of the behavior of the stove following the first 30 minutes of operation. In runs ' 1, 2, 3 (after 4-0 minutes), and 39, amounts of lead in the flue gas were within permissible limits. In run ty, the concentration dropped to allowable limits after the first 30 minutes, but increased significantly in the last 15 minutes of the first hour's run. This tendency to increase may be a joint manifestation of the irregular operation of the stove and the relatively short sampling period. A similar trend operating to a much less marked degree is noted in the results for the fourth hour of run 1. It should be noted, however, that in all instances in which the stove was operated for periods longer than 1 hour, the tendency to decrease is uniform and striking after the first 30 minutes. It follows therefore, that hazardous levels are reached from the flue gas mainly in the first 30 minutes of the run. Since these will be diluted at KE- 0008641 -9- once into existing room air, exposure to high levels by the operators of the stove is unlikely. For example, if the stove were started in an enclosure 20' x 20' x 10 ', the effluent from the stove would be diluted by more than an equal volume of air if the air change in the enclosure is only 1 time in 30 minutes. Furthermore, considering the temperature of the flue gas,, as noted on the data sheets for the respective runs, it is likely that sufficient ventilation will of necessity be provided for comfortable and efficient operation of the stove. This would dilute and reduce the lead concentrations in the effluent to safe levels even in the first 30 minutes of operation. VII. Recommendations (1) The present stove should be operated only under conditions of good ventilation. (2) The escape of lead into the air from the stve is a consequence of the failure of degradation of TEL in the generator tube and filter. Any changes in design which would increase the degree of decomposition of TEL should reduce proportionately the amount of lead in the flue gas.. If the stove must be operated under conditions of poor ventilation, attempts should be made to increase the efficiency of the generator and filter unit in breaking down the TEL or non-leaded fuel should be used. (3 ) Precautionary measures should be taken when the stove is torn down and cleaned. No significant amounts of organic lead were found either in the filter or the stove parts; conse quently no hazard from vapor or skin absorption will exist. However, the amounts of lead (in large part as metallic lead and lead oxide) found in the filter disc and stove are of the order HE 0009645 10 - of grams following a 4~hour run and these parts should not be cleaned when dry or in such manner as to evolve dust. Dipping of the parts in kerosene prior to brushing and scraping should safeguard this operation. All cleaning of the fire unit should be carried out in a place other than that in which cooking is done. Used filter discs removed at the time of cleaning, as well as the deposits scraped or cleaned from the stove should be buried or disposed of in the same fashion as other wastes from the kitchen. (U-) Towels or cleansing rags used to remove deposits from the walls of the cabinet or from kettles or pans should not be allowed to come in contact with foodstuffs. (5) The stove must never be operated without the filter disc. . (6) The potential hazard can be practically eliminated if the fire unit is allowed to operate for 30 minutes after starting outside the cookhouse. . Approved Robert A. Kehoe, M.D., Director From the Kettering Laboratory of Applied Physiology, University of Cincinnati, Cincinnati, Ohio. Reported by: Willard Machle, M.D. Jacob Cholak E.O. Jones W.R. Gall K 0009040 Figure 1 Table 1 Temperature Determinations Instrument: Hoskins Thermo-electric Pyrometer Type PA - Serial No. l6o45 Calibrated with boiling water. Atmospheric pressure not considered. ooo Burner surface - Pyrometer in contact . 1. Outer end (last slot) ------------------- 190 2. C e n t e r -------------------------------------- 8&5 3. Inner end (last slot) ----------------------- J&0o "V" Space between burners - at level of burner surface 1. Periphery of burner circle ----------------- 90 C 2, Center of "V" - 1/2 distance from apex to periphery------------------- 120 C 3- Apex of " V " ----------- --------------------240 C Temperatures at generator level A. Directly over burner arm 1. Outer e n d --------------------- 845 C 2. C e n t e r ---------------------------------- 970 C 3. Inside e n d ------ ---------------------- 90 C B. Between burner arms (generator level) 1. Periphery of burnercircle -- ------------- 110 C 2. l/2 distance from apex to periphery ----- l6o C 3. Apex of "V"----- 750 C Temperatures at filter level (over burner arm) 1. Outer e n d ---------------------------- 5^0 C 2. C e n t e r -------------- -------------------9l5 C 3 Inside e n d ------------------------------ 84-5 C Temperatures of filter case 1. At periphery over burner arm -- 2. At periphery over apex of "V" - 3 Top center -------------------- 4. 6" above center of filter case 5 . 12 " above center of filter case b. 12 " above center of burner arm 750 c 620 c 4-05 535 C c C 430 c Temperature of inside sheeting 175 c TABLE OF FLUE GAS LEAD RECOVERIES -- RUN 1 Tube # 1 Sampling Temp. C 2 Corrected Sampling Rate cfm at 2 5 C 3 Time Min Sample Run l*a i*b Volume Lead of in Sample Sample cu.ft. __ ykr-- 5.. . 6 Flue Gas per Gr.Carbon cfm 7 Gr.Carbon per Minute 8 Total Volume Flue Gas cu.ft. at 2 5 C 9=i+bx7x8 16 12 9 -5 2405 50 31 72.15 *.8 5.98 I6.I8 5000 13 125.0 2 .1+51 30 32 72.90 0.l6 5.98 16.18 3091* ll+ 127.0 2.1+21 60 62 11*5.3 O.56 6.25 16.18 6275 17 125.0 2 .10*5 60 62 11*6.5 0.50 6.26 16.18 6280 19 127.0 2.1*21 60 6l ll*5 . 3 O.65 6.21* 16.18 6250 Note: Average values of C0a and 0a during Run #1 were used to compute results for Tube #l6. Total Lead Recovered In SUMMARY TABLE OF LEAD RECOVERIES -- RUN #1 Source Stove Filter Disc by PbS0 4 Method (Spectrographic 59OO mg) Flame Valve, Burner, generator, Filter Case and Mixing Chamber (Spectrographic) Air and Fuel Lines Total Stove Test Chimney Effluent (Flue Gas) Chimney and Hood Deposits Organic Lead from Charcoal Adsorber Total Lead Recovered Total Lead In Fuel (Det. Anal. - 5380 mg) Partial Total mg. Total mg. C 1*228.0 720.0 9.0 1*9 5 7 . 0 0 280.08 1.50 10.50 521*9-08 5l*3l*.00 % TABLE OF FLUE GAS LEAD RECOVERIES -- RUN '2 Tube # % coa * oa 1 2 .3 Corrected Volume Lead Flue Gas Sampling Sampling Time of in per Gr.Carbon Total Volume Temp. Rate Min. Sample Sample Gr.Carbon per Flue Gas C cfm at 2 5 C Sample Run cu.ft. j"K. cfm Minute cu.ft. at 2 5 k 5 6a 6b 7 8 9 10 Il=6bx9xl0 1 1.2 19-3 125.5 2 453 50 31 7 3 . 5 9 2 . 9 5.98 4 .8 3 2750 2 1.05 19.65 II8.7 2475 30 52 7 ^.2 5 0.13 6.25 4 .8 3 2965 3 1.125 19 . 5 7 5 112.6 '2 . 5 5 3 60 62 1 5 3 . 1 8 0 . 1 4 6.39 4 .0 3 5880 5 1.115 19 . 5 2 5 1248 6 1,10 1 9 4 5 116.3 2438 2.392 60 62 46.28 0.26 53 53 126.78 0.12 645 6.53 4 .8 3 4 .8 3 5830 5130 Total Lead Recovered In E SUMMARY TABLE OF LEAD RECOVERIES -- RUN #2 -- -- -- ---- 1----------------- -------------------------- Partial Source Total mg. Stove - (Fire Unit) Filter Disc by PbS0 4 Method (Spectrographic 1*.000 mg) ' 4056 Flame Valve, Burner, Generator, Filter Case and Mixing Chamber 600 Air and Fuel Lines Total Stove 7 Test Chimney Effluent (Flue Gas) Chimney and Hood Deposits (Neglected) Organic Lead from Charcoal Total Lead Recovered Unaccounted for Total Lead in Fuel (Det. Anal. - 1*780 mg) Total mg. U663 112.2 0 0 1*77 5 . 2 56.8 1+832 C TABLE OF FLUB GAS LEAD RECOVERIES ~ RUN J2 Tube # % coa i2 % 0 3 Corrected Volume Lead Flue Gas Sampling Sampling Time of in per Gr.Carbon Total Volu Temp. Rate Min. Sample Sample Gr.Carbon per Flue Gas C cfm at 25C Sample IRun cu.ft. ? 1* 5 . ba 6b 7 8 cfm 9 Minute lb cu.ft. at 25 Il=6bx9xl 3 1. 10 19.5 131.5 2.28 0 30 31 6 8 4 5 .5 O 6.53 11*.52 2902 8 1.0 0 19 .6 129.3 2 .2 9 0 30 31 6 8 .6 0.1*9 7.18 11*.32 3 I9 O 5 o.95 19 .6 5 12 8 .0 2.295 60 6 l 137.6 0 .1*2 7.56 H*.32 6600 15 1. 10 1 9 4 5 117 . 8 2.355 60 6 l 11*1. 2 0 . 11 6.53 4.32 5710 13 0.95 19.6 II6 .9 2.365 60 60 ll*1. 8 0 .0 6 7.55 4.32 61*90 Total Lead Recovered In SUMMARY TABLE OF LEAD RECOVERIES -- RUN Location of Lead Stove (Fire Unit) Filter Disc (PbCr04 Method) (Spectrographic 3l*00 mg) Burner, Generator, Filter Case and Mixing Chamber Flame Valve, Air and Fuel Lines Total Stove Test Chimney Effluent (Flue Gas) ' Total Lead Recovered Unaccounted for Total Lead in Fuel (Det. Lab. 1*81*0 mg) "KrHal ` Total mg. Total mg. 3776.0 8 6 0 .0 2 6 .0 1*6 6 2 .0 19 9 .0 l*8 6 l.O 2 9 .0 * ~ 1*8 9 0 .0 C SUMMARY TABLE OF RESULTS Lead Balance Rune 1 , 2 and 59 Distribution - Effluent (Flue Gas) Filter Disc Stove other than filter disc Total Lead Recovered Unrecovered Lead t Total Lead in Fuel Burned Run #1 Run #2 Mg. of Pb % Mg. of Pb % 280.08 1*228.00 7i*1.00 521*9.08 181*.92 54& .00 5.16 77.75 15.57 96.1*8 5.52 100.00 112.2 1*056.0 607.O 4-7 7 5 .2 56.8 1*852.0 2.3 81*.0 12.5 98.8 1.2 100.0 Run Mg. of P 199.0 3776.0 886.0 1*861.0 29.0 1*890.0 TABULATION OP RESULTS -- RUNS #3 AND #4 Corrected Sampling Sampling Time Tube # Temp. Rate Minutes C cfm at 2 5 C Sample Run Lead Air in Sampled Tube cu. ft. mg. RUN #3 Flue Gas To per Gr.Carbon Total Volume Gr.Carbon per Flue Gas Sampling F cfm Minute cu. ft. Factor 1 120 2 II4.8 2.255 2.105 10 11 2 2 . 5 5 0.88 2 . 7 8 10 11 21.05 0 - 9 4 2 . 7 8 ll+.33 11,.33 438.35 438.35 '1 9 . 4 6 20.83 ' 3 162.8 4 162.8 2.O33 2.033 11 12 22.36 O.56 3.63 10 1 1 .5 20.33 0.28 3 . 6 3 111.33 li|. 3 3 624.0 598.0 27.95 29.45 5 157.5 2.055 10.5 1 1 . 5 21.58 0.01+5 3.63 1I+.33 598.0 27.76 6 156.8 2.065 10 10 20.65 0.04.0 3 . 6 3 ill.33 520.0 25.18 Total Lead in Flue Gas - Run #4 7 : 111 8 125 10 122 li 130.8 RUN 'k 2 .31J+ 15 17 314-.67 1.50 5 . 1 3 15.28 1330 38.37 2.233 15 l6 3 3 . 5 0 0.20 5- 53 15.28 1351 40.30 2.250 15 16 3 3 -7 7 0.12 5-53 15.28 1351 40.05 2.202 15 15 3 3 . 0 3 0.50 5-53 15.28 1267 38.35 Total Lead in Flue Gas - Run #5 Table 2 Concentration of Lead In Fltte Gas Time 1st 3C min. 2nd hour 4th hour Mgm. Pb in Flue Gaa Cu. Ft. Flue Gas 20 0 .0 Run 1 3000 -24-.a. 26.0 6275 6250 Mgm. Pb/10 cu.m. Flue Gas y 23.54- 1.35 1.5$ . 1st 30 min. 2nd hour 4-th hour 74-.6 16 .9 4-.9 Run 2 2750 566O 5130 9.60 1.0 1 0.34- 1st 30 min. 2nd hour - 4-th hour 14-6.6 20 <2 2.6 Run 39 2902 6600 64-90 16 .11 1.0 6 0 .15 1st 10 min. 2nd 10 min. 3rd 11 min. 4-th 10 min. 5th 10 ,5 min. 6th 10 min. 17.1 19 .6 10 .0 $.3 1.3 1.0 Run 3 4-36 4-36 624596 59$ 520 13.79 15.6 1 5.6$ 4.64 ' 0 .71 0 .66 1st 15 min. 2nd 15 min. 3rd 15 min. 4-th 15 min. 57-5 6 .1 4-.6 19 .2 Run 4- 1330 1351 1351 1267 15.2 6 2 .11 1.25 5-35 KE 0009654