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If nerve , incidentally or accidentally, contaminate public supplies, the choice of methods for detection and decontamination will be crucial. Satisfactory methods for and are assured.

Nerve in Public Water

By JOSEPH EPSTEIN, M.S.

W ATER WORKS ENGINE-ERS, alert Even the highly toxic and vesicant , to the hazards of radiological, biologi- when viewed in this light, presents little hazard cal, and agents, must be con- as a water contaminant. Lewisite hydrolyzes cerned primarily, among the chemicals, with almost instantaneously in water to the mildly the nerve gases. vesicant . The toxicity of the oxide is Many other chemical agents, because of in- apparently due to its trivalent content, trinsically low toxicity if admitted orally, or be- which may be oxidized with ease by chlorine cause of rapid hydrolysis to relatively nontoxic or other oxidizing agents to the less toxic pen- products, are unlikely to appear in hazardous tavalent state. In fact, trivalent arsenic be- in a large volume of water. For comes converted to the pentavalent state upon example, consider and cyan- standing in water. ogen , extremely toxic if inhaled. It If water containing lewisite is chlorinated would take 1 ton of either, uniformly dissolved according to standard procedures for bacterial in a 10-million-gallon reservoir, to reach a con- purification and is used for not more than 1 centration of 25 p.p.m. This in week to avoid possible cumulative effects, as water is considered physiologically tolerable much as 20 p.p.m. of lewisite can be tolerated for the average man if consumed in normal in (1). Calculation of the quan- quantities for a 1-week (1). tities of lewisite required to produce concentra- More specifically, it would take 1.66 tons of tions of physiological significance in the bodies either chemical to reach a 25 p.p.m. concentra- of water mentioned previously quickly reveal tion in Baltimore's 16-million-gallon capacity the improbability that significant contamina- Montebello Reservoir; 43,200 tons in Boston's tion of large bodies of water by lewisite will 415-billion-gallon Quabbin Reservoir; 13,500 occur as a result of general chemical warfare. tons in New York City's 130-billion-gallon By similar reasoning, the danger of contam- Ashokan Reservoir. ination of fairly large bodies of water during In reservoirs of less than 1-million-gallon general warfare by agents such as , capacity, the margin of safety owing to dilu- , chlorine, chloroacetophenone, di- tion is, of course, reduced. phenyl-chlorarsine, and the like is not partic- ularly great. Although it may appear that the danger of Mr. Epstein is chief, Sanitary Branch, contamination of water supplies by most chem- Biochemical Research Division, Chemical Warfare ical agents will be small, nevertheless, the pos- Laboratories, Army Chemical Center, Md. sibility of contamination to dangerous levels is a contingency which requires knowledge of the

Vol. 71, No. 10, October 1956 955 behavior of chemical agrents in water and of hydrolysis, from experimentation with rats, methods of or removal of the can be considered nontoxic. agents from water. By comparison of the toxicities to rats, it is Quantitative data applicable particularly to estimated that Tabun is about one-fourth as the treatment of water contaminated with all toxic as Sarin via the oral route. A reduction but the more recent nerve gases are available of the "tolerance level" by 10 to 100 times may (2, 3). For a general history of the nerve gases be advisable when infants or small children are and information relative to the mechanism of to be the consumers. The quantities of nerve action, effects, and treatment of nerve gas poi- gases, then, which are needed to bring the level soning, the reader is referred to articles by of contamination to a tolerance level for res- Holmstedt (4), Krop and Kunkel (5), Grob ervoirs of medium capacity do not appear to and Harvey (6), (7), and Krop and be of a magnitude sufficient to make contami- Loomis (8). nation improbable. In discussing the properties and behavior of In fact, it must be concluded that it is prob- the nerve gases Tabun and Sarin in dilute able that water will become contaminated to aqueous solution, the concentrations will be of hazardous levels if the nerve gases Sarin and the order of 1-2-10-4 WMor about 15-30 p.p.m., Tabun are employed during warfare. unless otherwise noted. The structures and chemical and common names of Tabun and Sarin as well as DFP, an agent similar to Sarin, Hydrolysis of Sarin are shown below. Qualitatively, the behavior of Sarin in water is very similar to that of DFP whose hydrolysis Toxic Levels of Nerve Gases in Water in dilute aqueous solution has been thoroughly The level of tolerance to Sarin in water has investigated (9). Like DFP, Sarin hydrolyzes been set at 0.5 p.p.m. with the limitation that to form two (equation 1), and the hy- the total volume of water taken per day will be drolysis is catalyzed by both acids and bases, no greater than 5 liters and that the period of although bases are more effective catalysts. ingestion will be no more than 3 days (1). This o 0 sets 2.5 mg. of Sarin as the maximum intake in C0H3-C-F+H20CH3-P-OH+HF1/ [1] a 24-hour period, and 7.5 mg. the maximum in C:EI3 CH3 a 3-day period. Except for the unlikely case of O CH 1CH recontamination, the concentration on the sec- CH3 CH3 ond and third day will probably be somewhat The rate of hydrolysis is dependent not only lower than the initial concentration of 0.5 upon the pH but also upon the type and quan- p.p.m., due to the natural and spontaneous hy- tity of dissolved in the water and the drolysis of the nerve gas. The products of temperature of the water.

Common Name Chemical Name Structure 0

Tabun ----- Dimethylamido ethyl phosphorocyanidate-(CH3)2N-P-CN 0 C2H5 CH3 0

Sarin - Isopropyl methylphosphonofluoridate HC-O-P-F /H CHZI CII, CH3 CH3 0 DFP Diisopropyl phosphorofluoridate HC 0-;-F

CH3 CH3

956 Public Health Reports In tlhe absence of large quantities 4of , the The rates of hydrolysis which one might half-life (ti/2) of Sarin in water at '250 C. (770 estimate from the use of equation 2 presupposes F.) at constant pH in the pH rangye of 6.5 to that the pH will remain constant during the 13.0 can be estimated from equation 2. time the Sarin is undergoing hydrolysis. For [2] small concentrations of Sarin, that is, up to 5 t'/2= (5.4X 108) (10PH) p.p.m., in containing some buffer ca- Thus at pH 7, the half-life of Sarin in water pacity, a constant pH will, in all probability, at 770 F. is 54 hours; at pH 8, 5.4I hours; at prevail. However, in the absence of significant pH 9, 0.54 hours, and so forth. B,etween pH buffer constituents in the water and at the 4.0 and 6.5, the hydrolysis rate of Sarin is at higher concentrations of Sarin under discus- a minimum; its half-life in this ratnge is ap- sion, the effect of the acidity produced by the proximately 175 hours. It is eviident from hydrolysis may be very important to the sta- equation 2 that above pH 6.5 the irate of hy- bility of Sarin in water. In slightly alkaline drolysis increases 10 times per unit increase in water of low buffer capacity, the production of pH. Below pH 4.0, the rate increas(es approxi- acids caused by a limited hydrolysis of Sarin mately 10 times per unit decrease iin pH. At can lower the pH to the range in which Sarin a given pH, the hydrolysis rate will[ vary by a exhibits maximum stability. Thus, under cer- factor of approximately 2 for each change of tain conditions, the hydrolysis of Sarin may 100 C. The relationship between tihe half-life produce materials which retard subsequent hy- of Sarin in dilute aqueous solutioni at 250 C. drolysis. In effect, Sarin can stabilize itself. and the pH of the water is shown graphically The rate of hydrolysis of Sarin is accelerated in figure 1. by anions other than hydroxyl . The hy- (irolysis of Sarin is more rapid in the presence Figure 1. The relationship between tthe half-life of such anions as trivalent phosphate or car- of Sarin at 250° C. and the pH of 'water. bonate ions than might be predicted from the 1000 IlFT pH of the solution. On the other hand, the hlydrolysis rate in the presence of rather large quantities of , chloride, or nitrate does not materially differ from the rate in water devoid of salts at the same pH. However, the 100 quantities of the catalytic anions, for example, trivalent phosphate, needed to produce appre- ciable effects upon the hydrolysis rate, will not normally be encountered in water supplies. 10 Depending upon the pH of the water, some

2 ions have strong catalytic effects upon 0 .C the rate of hydrolysis of Sarin. Cupric, man- ganous, and ions, to men- I"I tion a few, are very effective catalysts, whereas a x and ions are virtually inef- fective. Cupric and manganous salts are more effective in neutral or slightly acidic waters, whereas magnesium and calcium are more ef- fective in alkaline waters. 0.1 At pH 6.5 and 250 C., where magnesium salts show practically no effect upon the hydrolysis rate of Sarin, the half-life of Sarin in water containing only 1 p.p.m. cupric is 2 hours as compared to a half-life of approximately 0.01 175 hours in the absence of the metallic ion. 2 4 6 8 10 12 pH At pH 8.5 and 250 C., on the other hand, where

Vol. 71, No. 10, October 1956 957 the cupr'ic ion is ineffective (due presumably to From the data of Larsson (10) and HIolmstedt its insolubility) the half-life of Sarin may be (11), it appears that the rate of hydrolysis of decreased from 1.7 hours to 0.5 hours by the Tabun at the P-CN bond is for all practical addition of 100 p.p.m. magnesium ion. The purposes independent of the hydroxyl ion con- proportional effectiveness of magnesium ion is centration between the pH range of 4.0 to ap- greater at alkalinities above pH 8.5, but is less proximately 8.5. The half-life of Tabun in necessary because of the effectiveness of hy- this pH range at 20°-25° C. is 2-4 hours. droxyl ion alone at a higher pH. Thus, in waters of high magnesium or cal- cium ion content, or in waters containing even Detection trace quantities of some heavy metal ions, the Although a nerve gas attack would alert hydrolysis rate of Sarin may be much more water works personnel, Sarin in water in con- rapid than that predicted by equation 2. In centrations of at least 35 p.p.m. is not detectable most natural waters, however, the quantity and by odor or taste. Water containing concentra- type of dissolved solids are such that prediction tions of the hydrolysis products of Sarin as of the hydrolysis rate may be made from equa- high as 200 p.p.m. was acceptable to rats. How- tion 2, provided, of course, that the pH is main- ever, Tabun, which possesses a fruity odor, is tained constant during the hydrolysis. detectable by smell in rather low concentra- tions. Furthermore, suspicion as to potability Hydrolysis of Tabun of water supply would be aroused by the odor of hydrocyanic which is formed by the The hydrolysis of Tabun, like that of Sarin hydrolysis of Tabun. Unlike Sarin, Tabun, and DFP, is catalyzed by acids and bases, and through its released cyanide, will alter the bases are more effective than acids (10). Un- "chlorine demand" of a water. like Sarin and DFP, whose products of hydrol- The uptake of chlorine in the reaction with ysis are independent of the catalyst used, Tabun Tabun will depend upon whether the chlorina- is destroyed by attacks upon different parts of ting material is or chloramine. the molecule by acid and , and the products The chloramines will react only with cyanide of hydrolysis are different. In alkaline solu- ion which becomes available as a result of the tion, the to cyanide linkage is hydrolysis of Tabun. The uptake of chlorine cleaved, resulting in the formation of a substi- when hypochlorite is one of the reactants is also tuted phosphonate and sodium cyanide. In, due to its reaction with cyanide, but apparently acid solution, the Tabun molecule is cleaved hypochlorite ion catalyzes the decomposition between the phosphorus and . Both of Tabun to form cyanide so that, in effect, the attacks result in destruction of the toxic prop- uptake of chlorine is due to the Tabun as well as erties of Tabun. (See below.) to the hydrolysis product. In alkaline solution, the formation of acid If appreciable quantities of Sarin have hydro- tends to lower the pH of the solution; in slight- lyzed, and the contaminated water if of low ly acid medium, the hydrolysis products are one buffer capacity, the low pH of the water, re- acid and one base, and the pH remains constant. sulting from the acidic hydrolysis products,

0 (C H3) 2N P Hydrolysis OH-/ C2H50 0- + CN- + H+ (CH3)2N 0 of H/ P + H20 Tabun HO 0 CvH50 C N p + HN(CH13)2 C,H50 C N

958 Public Health Reports may serve to warn that contamination has oc- can probably be modified to increase the sensi- curred. An abnormally high fluoride ion con- tivity. centration in water should arouse the suspicion The test has been adapted for field use and is of the operator as to the potability of the water. included in two water testing However, since only 13 percent of the Sarin kits described in technical bulletins (13, 14). molecule after complete decomposition is fluo- The response of three small species of fish, the ride ion, probably only when relatively high fathead minnow (Pimephales pmornelas), the concentrations are in the water supply would green sunfish (Lepomnis cyanella) , and the - the water be suspected because of fluoride ion fish (Carassuis auratus) to Sarin and Tabun concentrations. are useful to the detection and, in some cases, The existence of fluoride ion and the low pH estimation of small conicentrations of nerve can only serve to point out that undecomposed gases in water. The approximate LC50 (con- Sarin may be present, not that it is. The same centration of agent required to kill 50 percent limitations apply to detection methods via the of the test animals) for exposures of 10, 15, phosphorus moiety of the molecule. and 20 minutes at 700-750 F. for the three It appears reasonable to conclude that dan- species are shown in table 1. gerous concentrations of Sarin may remain un- It is possible to decrease the concentration detected if only the nonspecific pH and chlorine of the nerve gas necessary to produce an LC50 demand tests and the tests for the fluoride ion by increasing the exposure time, but with in- and phosphorus are used. However, judicious creased exposure times, the effect of the pH of choice of methods for estimation of fluoride ion the w%vater becomes very important due to hy- concentrations and correlation of these tests drolysis rates of the agents. Thus, for a 24-hour with others such as pH and the alteration of period, the LC50 of Sarin for the sunfish is 2 the pH of the water observed at various time p.p.b. (.002 p.p.m.) if the water is kept at pH intervals may be helpful in the detection and 6.5 (mininmum hydrolysis), but 9.5 p.p.b. at estimation of Sarin. pH 8.0. Similar data have been obtained with Depending upon the method used for esti- the other species for Sarin and Tabun. mation of fluoride ion, one may obtain varying The LC50 values are increased if the tempera- values for fluoride ion in waters containing both ture of the water is lowered. For a change of unihydrolyzed and hydrolyzed Sarin. If the approximately 250 F., the LC50 values for a methods recommended for fluoride in Standard 10-minute exposure should be multiplied by 6 Methods for the Examination of Water and to 8 for the three species. Sewage, Ninth Edition, 1946, are used, then the total of the hydrolyzed and unhydro- Table 1. Approximate LC50 of Sarin and Tabun lyzed Sarin will be determined, since under the (p.p.m.) for fish at 70-75' F., by various conditions of acidity required for this test, the exposure times bound fluorine in Sarin will be converted to ionic fluorine in a few minutes and thus will be Tabun Sarin determined as ionic fluorine. On the other hand, if fluoride ion is determined in neutral Fish species Minutes of Minutes of solution, and in the absence of hydrolytic cata- exposure exposure lysts, then only the fluoride ion present at the time of the test will be determined. 10 15 20 10 15 20 Both Sarin and Tabun in the presence of their Green sunfish-1.5 1.00.700.350.230.27 hydrolysis products may be detected and esti- Fathead minnow- 1. 5 . 9 . 60 . 63 . 40 . 3 mated rapidly and in very low concentration by Goldfish -2.4 1. 7 1.3 .93 .6 .5 their reaction with benzidine or o- and alkaline peroxide solutions (12). By means of Decontamination this reaction, the author and co-workers have been able to estimate quantitatively as little as On the premise that decontamination proce- 0.1 p.p.m. of Sarin in water, and the method dures should reduce the level of Sarin and

Vol. 71, No. 10, October 1956 959 Tabun concentration to 0.1 p.p.m., field tests Table 2. Half-life of Sarin (2X 10-4M) in water have shown that coagulation with ammonium in the presence of free chlorine , followed by filtration through diatomite or sand filters is not an effective decontaminat- Termperature pH p.p.m. Half-life in ing procedure. A procedure involving the use C12 mninutes of ferric chloride as coagulant and powdered I- _L, limestone as coagulant aid, followed by filtra- tion through diatomite filters is also ineffective. These materials are used in the Corps of Engi- neers Mobile Water Purification Unit (15). Approximately 62 pounds of would have to be added to eaclh 1,000 gallons of water to reduce the concentration of 30 p.p.m. to 0.1 p.p.m. A smaller total dose of carbon can ac- 770 F. and 350 F. at various pH's and in the complish the same objective if a multiple treat- presence of free chlorinie, added as high test ment procedure is applied. However, the time lhypochlorite (HTH). involved and the multiplicity of operations 'rhe importance of pH in this rieaction is seen make such a procedure objectionable. from the figures shown in table 2 on experi- Sarin in water is rapidly hydrolyzed by the ments at 770 F. Only one-eighth of the chlorine catalytic action of strongly basic concentration was required at pH 7.0 as was resins, such as Amberlite IRA-400 and Nalcite iequired at pH 6.0 to give approximately the SAR and strongly acidic cationic resins suclh same rate of destruction. Approximately one- as Dowex 50 and Amberlite IR-112. The tlhird the concentration of chlorine was required anionic resins are more effective, and function at pH 8.0 to produce the same effect at pH 7.0, not only as catalysts, but also remove the hydro- ind so forth. It can also be seen by comparing lytic products. In doing so, however, the resins the half-lives of Sarini in the presence of equal lose their available hydroxyl ion and ultimately concentration of chlorine and at the same pH their ability to catalyze the hydrolysis. but at two different temperatures, for example, Furthermore, in water of appreciable dis- pH 6, that the rate of destruction is approxi- solved content, the anions of the salts re- mately doubled for each rise of 100 C. place the hydroxyl groups in the resin (and Wlhere time of treatment can be extended to cations, the hydrogen ions of the cationic resins) several hours, much lower concentrations can resulting in a decreased efficiency of the resin, be used to produce effective decontamination. since the efficiency is related to the number of For example, by maintaining the water at pH available lhydroxyl or hydrogen ions in the 8.0, addition of 5 p.p.m. chlorine will reduce resin. The use of resins for large scale water the concentration of Sarin from 30 to 0.1 p.p.m. decontamination is not economically feasible. in approximately 3 hours. Figure 2 shows At least two feasible methods for the de- half-life of Sarin at 25a C. at pH ranges be- struction of Tabun and Sarin in water supplies tween 6 and 9 in the presence of different con- are available. Both methods are based upon centrations of free chlorine. an acceleration of the normal hydrolysis rate. A dosage of chlorine to be added to a water The methods involve clhlorination or alkalini- supply may be calculated from the values given zation. in figure 2, a knowledge of the concentration of Chlorine will not react with Sarin, but hypo- Sarin in the water, the temperature and pH of ion is a very effective catalyst for the the water. The action of hypochlorite may be hydrolysis of both Sarin and Tabun. Com- completely inhibited, however, if amines or am- pounds containing combined clhlorine, suclh as monium salts are present in the water because chloramine T, on the other hand, exert prac- of the very rapid reaction of hypochlorite with tically no catalytic action. Table 2 shows the the nitrogen compounds to form chloramnines half-life of Sarin in water at approximately (16) which are catalytically inactive.

960 Public Health Reports Chlorine as hypochlorite will destroy Tabun, chlorinate. The rate of hydrolysis is followed and the cyanide produced upon hydrolysis of by the test methods described (14) and the Tabun will consume the chlorine. quantity of alkaline material to be added is Satisfactory procedures for decontamination regulated by the rate of hydrolysis. The alum of Sarin have been developed, utilizing the cata- or ferric chloride function not only as coagn- lytic properties of hypochlorite. In field trials, lants but also to reduce the pH of the water to HTH was used as the source of hypochlorite normal acidities. Water treated by either pro- and, because rapid decontamination was de- cedure is potable and palatable. sired, 100 p.p.m. chlorine was used. Follow- ing decomposition, the hypochlorite concentra- tion was reduced to less than 1 p.p.m. by treat- Conclusion ment with . From the preceding discussion, it appears Another satisfactory procedure for decon- reasonable to conclude that, in the event of gen- tamination proved by field trials is to raise the eral chemical warfare, the nerve gases Tabun pH of water to approximately 10.0 with soda and Sarin must be considered potential water ash, slaked lime or magnesium lhydroxide, al- contaminants because of the very small quanti- low the Sarin or Tabun to hydrolyze, and when ties of these agents required to produce toxic tests indicate that the concentration of the nerve symptoms from ingestion. The hazard due to gas is 0.1 p.p.m. or less, use a coagulant such as Tabun, however, is lessened somewhat because ammonium alum or ferric chloride, filter and of its ease of detection in water by taste, odor, and chlorine demand test. Sarin presents a Figure 2. The relationship between the half-life more difficult problem inasmuch as specific de- of Sarin at 250 C. and the pH of water for dif- tection methods are necessary. Once detected, ferent concentrations of free chlorine. both Sarin and Tabun can be rapidly destroyed 1000 I I I by simple decontamination procedures. A- 5 ppm. Free chlorine . - 10 p.p.m. Free chlorine REFERENCES 0- 50 p.pm. Free chlorine *-100 ppm. Free chlorine (1) U. S. Army Surgeoni General's Office: Treatment of chemical warfare casualties. Appendix II. Detection of contaminated water and its puri- 100 fication. TM 8-285. Washington, D. C., U. S. Government Printing Office, 1951. (2) Buswell, A. M., Gore, R. C., Hudson, H. E., Jr., Weiss, A. C., and Larson, T. E.: War problemns in analyses and treatment. J. Am. Water e Works A. 35: 1303-1311 (1943). L.: Chemical contamination of water sup- E (3) Rubin, 10 plies. J. New England Water Works 56: 276- 10 287 (1952). (4) Holmstedt, B.: Nerve gases unveiled. Chem. & Engin. News 31: 4676-4678 (1953). (5) Krop, S., and Kunkel, A. M.: Observations on pharmacology of the anticholinesterases Sarin and Tabun. Proc. Soc. Exper. Biol. & Med. 86: 530-533 (1954). (6) Grob, D., and Harvey, A. M.: The effects and treatment of nerve gas poisoning. Am. J. Med. 14: 52-63 (1953). (7) Wood, J. R.: Medical problems in chemical war- fare. J. A. M. A. 144: 606-609 (1950). (8) Krop, S., and Loomis, T. A.: Treatment of anti- cholinesterase poisoning by phosphate insecti- 0.1 . cides and "nerve gas." New York State J. 6 7 8 9 pH Med. 56: 1766-1768, June 1, 1956.

Vol. 71, No. 10, October 1956 961 (9) Kilpatrick, M., and Kilpatrick, M. L.: The hydrol- istry and Applied Spectroscopy. Feb. 27-March ysis of diisopropyl fluorophosphate. J. Phys. & 2, 1956. Colloid Chem. 53: 1371-1385 (1949). (13) U. S. Department of the Army: Water testing and (10) Larsson, L.: The hydrolysis of dimethylamido- screen kits AN-M2 MIAI and MI. TB ethoxy-phosphoryl cyanide (Tabun). Acta CML-40. Washington, D. C. 1955. chem. Scandinav. 7: 306-314 (1953). (14) U. S. Department of the Army: Water testing (11) Holmstedt, B.: Synthesis and pharmacology of kit, M4. TB CML-M-4. To be pub- dimethylamido-ethoxy-phosphoryl cyanide (Ta- lished. bun) together with a description of some allied anticholinesterase compounds containing the (15) Lowe, H. N., Jr., Schmitt, R. P., and Spaulding, N-P bond. Acta physiol. Scandinav. 25, Suppl. C. H.: Introducing-Army's new mobile water 90: 12-120 (1951). purification unit. Eng. News Record 151: 39- (12) Epstein, J., and Bauer, V. E. The colorimetric 41, Sept. 24,1953. estimation of tetraethyl pyrophosphate, HETP, (16) Weil, I., and Morris, J. C.: Kinetic studies on the and some phosphono and phosphoro fluoridates. chloramines. J. Am. Chem. Soc. 71: 1664 at Pittsburgh Conference on Analytical Chem- (1949).

The Mayo Memorial

Forming the heart of what is virtually a Construction was started in 1951 and com- complete medical center on the University of pleted in the early autumn of 1954. Minnesota campus is the recently completed The new building brings together the facili- Mayo Memorial. The university's School of ties of the School of Public Health formerly Public Health occupies 2½/2 floors of the new scattered in several university buildings. On building's 14-story tower section. the 11th floor are laboratories, offices, and The Mayo Memorial, which was dedicated classrooms for work in environmental sanita- on October 21, 1954, is the fulfillment of tion and epidemiology. The 12th floor houses an idea begun more than a decade ago. In facilities for biostatistics, health education, and 1939, shortly after Doctors Charles H. and the course in administration. The William J. Mayo had died, the Governor public health nursing unit, offices for the non- of Minnesota appointed a Mayo Memorial professional health and hygiene courses, and Commission to propose an appropriate monu- other offices are located on the 13th floor, ment. After considering many projects, the which the school shares with the medical commission agreed that a center for teaching school administration. Conference and read- and research as a building of the University ing rooms are provided on each of the three of Minnesota Medical Center would be the floors used by the School of Public Health. most fitting memorial. During their lifetime, In addition to the tower section, the Mayo the Mayo brothers had devoted much time, in- Memorial has three 6-story wings that connect terest, and aid to the work of this institution. with existing hospital and medical school A Committee of Founders started the proj- buildings. The building has facilities for edu- ect on its way. Funds were raised by legisla- cation, research, and service in connection tive appropriation, public subscription, and with various departments of the medical grants from public and private agencies. school.

962 Public Health Reports