Toxic chemical materials - Journal of Chemical Education (ACS

Toxic chemical materials. Douglas G. Nicholson. J. Chem. Educ. , 1944, 21 (5), p 219. DOI: 10.1021/ed021p219. Publication Date: May 1944. Cite this:J...
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Toxic Chemical Materials FIRST LIEUTENANT DOUGLAS G. NICHOLSON Chemical Warfare Service, United States Army


HE average layman shares the popular concept that the materials and methods used in chemical warfare are more terrible and less humane than those nsed by other branches of our military forces. Regardless of the method nsed, when two or more nations are involved in a war, we shall always have casnalties and suffering. Thus no single type of warfare can be considered humane. The mechanics of a steel pellet flying through space ultimately striking an individual, "liquidating" him, are quite simple and rather easily understood. At the same time the use of casualty-producing gases which are capable of entering trenches, foxholes, and shellholes is apparently more mysterious and is often considered a more terrible form of warfare. We all have used electricity in some f o m in our daily work. Yet very few individuals have a concrete conception of the constitution of the ultimate particles of electrical energy. Electricity, in the form of lightning or a short circuit in a power plant, can be very bannful and is capable of doing a great deal of damage. When handled properly it is an essential and valuable tool in everyday work. In a similar manner the lack of understanding of the capabilities and limitations of military gases can increase their casualty-producing effects. Proper training of civilian and military personnel in first aid measures, useof protective equipment, and the detection and limitations of such agents can do much to reduce their casualty-producing properties. During World War I approximately one-fourth of all American casualties' were caused by chemical agents. Statistics have shown that a chemical casualty had 12 times as good a chance of full recovery as one caused by other means. Thus, in accepting these figures, we mustagree that chemical warfare is more humane than other forms of combat. From the point of view of the well-trained soldier, it is only proper to state that by using knowledge gained in his training, by making use of discipline measures taught h i , by using the various protective devices and first aid remedies given him, he may find chemical agents to be bothersome, and to cause some discomfort, but under normal conditions he will not find them too dangerous. Any reduction in vigilance and proper techniques will result in serious and unnecessary casualties from these materials. Although considerable time and effort have been spent in training mu civilian personnel in protective and first aid measures it is sincerely hoped that any possible use of toxic chemicals will be confined to combat zones. There is no assurance that this will be the case.

In considering chemical warfare agents, i t may be well to understand the several classes into which these materials are divided. These are (1) the tactical and (2) the physiological classifications. Tactically we may have (a) casualty gases, (b) harassing gases, (c) screening smokes, and (d) incendiaries. In turn, the physiological classification may be divided into five groups as follows: (a) choking gases, (b) blister gases, (c) tear gases, (d) vomiting gases, and (e) blood and nerve poisons. The screening smokes and incendiaries will not be discussed in this paper. Since the technical names, symbols, or formulas associated with individual compounds and elements do not have a great deal of importance to the average soldier or layman, the Chemical Warfare Service of our country has adopted the series of symbols mentioned in this paper. In this manner the workman in a production plant as well as the soldier in battle can refer to "FS'as a smoke-producing liquid without becoming involved in any technical terms or symbols. As new chemical materials are 'developed, the present list of CWS symbols will be expanded. Quite recently an attempt has been made to standardize our CWS symbols and associated terms with those used by the British army. Table 1 shows the results. TABLE i

common nomr4 Agcnl

E $ :: ~ u = t a r d-

HS M-1








Vesicant ,Vesicaot

Blister gas Blister gar


Vesicant ~ ~ Sternutator Systemic poison

Blister gas T~~~ ~ gar ~ Vomiting gas Blood and nerve poiron


mixture rombenzy~eyanide Phenyldichlorar~ine Arsine Cysnogen

old S J ~ ~ ~ ONW I (U.S.) Symbol


.. .. .. ..


systemic poison

B I O O ~and nerve


systemic poison




~ ipoison i ~ t gas er



It is believed that Chemical Warfare Service materials which are not mentioned in theabove table will retain their old symbols. All agents formerly classified as "vesicants" are now classified as "blister gases"; those formerly classified as "lung irritants" are now "choking gases"; "lacrimators" are now classified as "tear gases"; and "sternutators" are now classified as "vomiting gases." The materials formerly classified as "systemic poisons" are now classified as "blood and nerve poisons." It should be remembered that the term "gas" is used in a very broad sense in these classifications. Xany of paper the term implies putting a man ,rout . these materials are either solids or liquids a t ordinary of action" and does not mean death. 219




temperatures, although they are called "gases." An attempt has been made to adhere to the newer classifition in the discussion of the various agents. In order to be an effective chemical warfare agent a

similar to dirty crankcase oil in both color and viscosity. It has a garlic-like odor. When pure it freezes at 14.4"C., and boils a t 228'C. with slight :decomposition. Its specific gravity is 1.274 a t 20°C.

material must meet with several important qualifications: (1)It must be effective in relatively low atmospheric concentrations. (2) It must be capable of being produced in large quantities from raw materials which are rather readily available. (3) It should have a density greater than that of air. (4) I t must be relatively stahle nnder storage conditions. (5) It should be stahle under conditions of impact such as are encountered in exploding shells. (6) If a gas, i t must be capable of being readily liquefied and easily vaporized when the pressure is released. One of the older and hetterknownof our chemicalwarfare agentsis "mustard" gas. Chemically this material is @,@I-dichlorodiethylsnlfide (C1CH2CHBCH2CH2C1). When pure it is a nearly colorless liquid, although the commercial product is a dark brown liquid appearing

Mustard gas has the Chemical Warfare Service symbol H, and is classified as a persistent material, as it will remain in an area from several hours to several days (depending on wind and temperature conditions). I t is hardly affected by water a t ordinary conditions, although hot water or steam will cause its hydrolysis to take place, with the formation of hydrogen chloride and thiodiglycol. It is known as a "blister gas" since exposure to it will cause severe bums and blisters on the skin. Its vapors will cause skin irritation as well as severe irritation of the eyes. If inBled for some time mustard vapors will damage the lung tissues in a manner similar to that caused by a "choking gas." The liquid mustard droplets will penetrate normal clothing as well as "impregnated" clothing (chemically treated ciaing). The chemically treated clothing usually gives

ample protection from vapors and minute droplets, while normal garments give but little protection in this respect. In addition to the special impregnated clothing (also known as permeable clothing) there is also available an impermeable type which will give protection against both the liquid as well as the vapors of this agent. This material is quite similar to the fabric used in the common oilskin type of raincoat. Thus, extreme discomfort soon results if one is required to do any amount of strenuous work when wearing such a garment, as it provides no means for skin ventilation. Figure 1shows members of a Chemical Warfare Service Laboratory Company dressed in such uniforms, hooded and masked, removing a sample of a toxic material from a projectile. Burns on the skin resulting from mustard vapors appear quite similar to those resulting from a severe case of sunburn. The degree of the burn is proportional to the time of exposure as well as the vapor concentration. A definite itching sensation accompanies such exposure. Burns from the liquid agent result in the formation of large blisters. Often a time interval of six to twenty hours passes before the blisters attain their maximum size. The blisters are filled with a nonblistering, clear liquid. Case history tends to show that different individuals exposed to the same concentration of mustard vapor for the same length of time often exhibit different degrees of burning. F i s t aid for exposure to liquid mustard consists in rapid removal of &l excess of the agent, using a cloth or other absorbent material in a blotting-like action. This is followed by application of protective ointment (supplied to each soldier) which is rubbed thoroughly over the exposed areas. If the ointment is not.available the exposed area or areas should be thoroughly washed with strong soap and water as soon as convenient. If neither the ointment nor soap and water are available the exposed areas should be washed with gasoline to remove the agent. Care should be exercised not to use the ointment in the eyes, even though they are seriously affected by both mustard vapor as well as the liquid. First aid for mustard in the eyes consists of flushing out the areas with large amounts of water. Partial or total blindness may result if such action is not taken immediately. The gas mask, if donned as soon as the agent is detected, will give ample protection for eyes, face, and lungs. Small areas of clothing which are contaminated with minute droplets of mustard should be treated immediately with the protective ointment; heavy liquid contamination of clothing should be followed by immediately cutting out the contaminated areas, or removal of the garment or garments as soon as possible. Areas contaminated with H are usually posted to show their location. In this way further contamination of feet and clothing by brushing against woods, bushes, etc., is avoided. Soles of shoes are nevertheless decontaminated by stamping and shuffling the feet through a "shuffle-box" containing a mixture of chlo-

rinated lime (bleach) and soil. In certain situations it is necessary for personnel to work in contaminated areas. Such areas are decontaminated by special crews wearing protective clothing. For roads or large surfaces these men may use either a special organic decontamination agent dissolved in acetylene tetrachloride (CZH~CL)(generally used on planes, guns, vehicles, and special equipment), or a slurry of bleaching powder suspended in water. The decontamination agents are generally sprayed on the surfaces to be treated. Figure 2 shows a crew of men dressed in impervious clothing, decontaminating a vehicle with the organic material dissolved in acetylene tetrachloride.


The healing of mustard blisters is hastened by using sterile bandages saturated with amyl salicylate (three or four applications per day for several days). Lewisite (named for Dr. W. L. Lewis), is hetachlorvinyldichlorarsine (C1CH:CHAsCl2) and has the Chemical Warfare Service symbol L . It is classified as a persistent "blister gas." It freezes a t -18'C., and boils a t 190°C. Its density a t 20°C. is 1.88. When pure the liquid is colorless to slightly yellow. The commercial product is dark brown and has the odor of geraniums. It is soluble in most of our common oils as well as in liquid mustard. I t is practically insoluble in water, but hydrolyzes readily forming hydrogen chloride and chlo~inylarseniousoxide. This latter hydrolysis product is toxic (since it contains arsenic), though nonvolatile. Under conditions of extremely high humidity or heavy rainfall, lewisite is not a particularly persistent agent. In most other respects the action of this agent is very similar to that of mustard. Case histories indicate that there is more discomfort from lewisite bums than from those of liquid mustard of an equal concentration. Lewisite is particularly dangerous to the eyes. Unless treatment is administered within five minutes after exposure to the liquid, partial or total blindness may result. A specific first aid remedy has been de-

veloped, and if the eyes are treated with this material shortly after exposure to the liquid agent complete restoration of vision is usually possible. First aid for L is, in general, quite similar to that mentioned for H. Exposed areas of the skin are cleared from as much of the agent as possible, and then are treated with an 8 per cent solution of hydrogen peroxide or with protective ointment as outlined under treatment for H. When available, strong soap and

water are a very good 6 r s t aid remedy for L. All contaminated clothing should be removed as soon as possible. Protective clothing, either impervious or permeable, will give. protection from the vapors of this agent. Ethyldichlorarsine (GHsAsC12), Chemical Warfare Service symbol ED, is a moderately persistent casualty and harassing gas which is generally classified as a "blister gas." It has a biting odor in air, melts a t -30°C., boils a t 156'C., and is soluble in ethylchloride. It hydrolyzes slowly, forming hydrogen chloride and ethylarsenious oxide (latter material is toxic but not volatile). Its blistering action is estimated to be about one-sixth as powerful as that of H. Exposure to this agent tends to cause paralysis of the fingers. Its vapors cause hums to the respiratory tract. The use of a gas mask and the wearing of protective clothing will give

adequate protection against this agent. First aid for ED is essentially the same as that for H. ED is often used in offensive situations where H would not be permitted because of the higher persistency of the latter. Chlorpicrin, Chemical Warfare Service symbol PS, has the formula CClaN02,and may be considered as chloroform in which the H atom is replaced by an NOz (nitro) group. Thus, it is sometimes called nitrochloroform, or trichlornitromethane. It is classified as a moderately persistent harassing and casualty agent since i t is both a tear and a choking gas. It has an odor similar to fly paper, melts a t -69.2'C., boils a t 112'C., and is soluble in chloroform, phosgene, and liquid chlorine. It is not appreciably hydrolyzed by water, aqueous acid, or aqueous solutions of acid or alkali. Alcoholic alkali solutions will promote its decomposition. It shows slight corrosive effect on metals. The harassing nature of this material can he illustrated by a personal experience of the author. One sniff from a sniff set caused a t least 20 consecutive sneezes, and a distinct burning sensation remained in the nasal and throat passages for a period of two or three hours. Liquid droplets of this material may he removed by washing with soap and water. A gas mask will give adequate protection against the vapors for nasal and throat passages. In the more recent months we have heard more or less about the so-called "new" war gases. Many of these reports are unfounded and should be discounted as rumors. While these materials are generally considered to be in the experimental stage, a few facts concerning the composition and action of one such class can he revealed. Brigadier General A. H. Waitt has desdbed this class of agents, the "nitrogen mustards,'' in a recent p~hlication.~ Agents in this class may he either solids or liquids, and their color varies from colorless to pale yellow. The odor of these materials varies from "slightly fishy" to none a t all. They are classified as hlister gases which are generally less persistent than mustard and are also less severe in their blistering action, but they are believed to have more severe action on the eyes than do the other, better-known materials. Up to the present point we have discussed the persistent and the moderately persistent agents. Of the nonpersistent gases we have two which are rather well known. These are chlorine (Chemical Warfare Service symbol C1) and phosgene CG). Since most of our elementary textbooks cover the properties and action of chlorine in a complete manner this substance will not be discussed. Chemically, phosgene is carbonyl chloride (COCl2) It is classified as a choking casualty-producing gas. It has an odor similar to ensilage or freshly cut hay. Its melting point is - 104°C. and i t boils a t 8.30°C. When dry i t has no corrosive effect on metals. I t hydrolyzes rapidly, forming COz and HC1. It causes a distinct


*WAITT,"Nitrogen mustard

No. 3, p. 44 (1943).

gases," Infantry

Journal. L11,

burning sensation in the eyes, throat, and respiratory solvents as well as in other agents such as PS. It is very passages, and one or two breaths in sufficiently high corrosive to iron and must be held in lead- or enamelconcentration may be serious or even fatal. Its per- lined containers. All materials which have been discussed up to the sistency usually varies from 1 to 10 minutes. Often a delay of several hours takes place between the time of present time are solids, liquids, or gases which have exposure and the first physiological symptoms. The noticeable vapor pressures a t ordinary temperatures. use of this agent in a surprise attack on sleeping troops is Thus, i t is the vapors which affect the respiratory often very effective. The standard gas mask offersade- organs, although liquid blister gases are also casualty quate protection. From this discussion it is readily producers. Contrasted with this group of agents we seen that any laxness in training and discipline on the have a class known as vomiting gas. These materials part of military personnel would greatly increase the are dispersed, usually by thermal methods, as finely divided solid smoke particles. If breathed they are danger from phosgene. Because of the low boiling point of phosgene (rapid capable of causing sneezing, coughing, vomiting, and rate of evaporation), an agent called diphosgene depressing headaches. The chemical adsorbents in the (Chemical Warfare Service symbol DP) has been de- gas mask canister do not remove these materials. veloped. Chemically this material is trichlormethyl- There is, however, a mechanical filter apparatus in the chloroformate (ClCOOCCk). It is a moderately per- canister which actually filters the air and thus removes and its these agents by a strictly mechanical method. There sistent agent. Its melting point is -57'C. boiling point is 127°C. It has an odor similar to that of are three materials which fall in this class. These are phosgene. It slowly hydrolyzes in water or water diphenylamine chlorarsine [NH(CsH&AsCl], Chemical vapor, forming Copand HC1. Physiologically, it bums Warfare Service symbol DM; diphenylchlorarsine the lower breathing apparatus, causing edema, and also (CBH&ASCI,Chemical Warfare Service symbol DA; Chemical Warirritates the eyes. The gas mask will give ample pro- and diphenylcyanarsine (CBH~)~ASCN, tection. fare Service symbol CDA, or DC. DM, also known as Individuals who have been exposed to either CG or Adamsite, has a melting point of 195OC. and boils at DP should be kept warm and should not be permitted to 410°C., with decomposition taking place below the exert themselves. They should be forced to lie still boiling point. First aid measures for the canaryand should be wrried to the rear as promptly as possible. colored irritant smoke consist of breathing the chlorine Coffeeshould be given as a stimulant. vapors emitted from bleaching powder. This agent The Chemical Warfare Service also uses a class of ma- may be released from a candle, or grenade, or from a terials called tear gases. The materials generally con- burning-type shell. tain alpha-halogen-carbonyl groups, and usually have DA has a melting point of 44'C. and boils a t 383'C. relatively low vapor pressures. When the vapors of with decomposition. It is practically odorless. On these materials strike the eyes they cause irritation and storage it slowly decomposes, and on exposure to water a copious flow of tearshence the name tear gases. i t hydrolyzes slowly. It may be neutralized by caustic This class of agents has been used to good advantage in alkalies or chlorine. This agent is also dispersed by breaking up civil riots and is of great value in simulat- means of thermal-type munitions. ing noupersistent toxic gases in troop and civilian trainCDA8 has an odor suggesting bitter almonds. It ing programs. In the field their use will force the wearing melts a t 31.5"C. and boils a t 350°C. It corrodes iron of a gas mask; thus they are considered as harass- and steel but is stable on storage. The methods of ing gases. neutralizing and protecting against this agent are simiChloracetopbenone (Chemical Warfare Service sym- lar to those mentioned for DM and DA. bol CN) is phenylchlormethylketone (CCHSCOCHZC~). Individuals who have been exposed to these vomiting The commercial product is a light-colored solid having gases should be removed from the area as soon as posa melting point of 59'C. and a boiling point of 247OC., sible. Usually the effect lasts but a few hours. Norand is soluble in most organic solvents. Its odor, in low mally such individuals will be able to return to their concentrations, is similar to that of apple blossoms. It duties thereafter. may he dispersed in the atmosphere a t high temperaNo discussion of gases used in war would be complete ture or by spray of one of its solutions (such as a solu- without a few remarks concerning the gases which are tion in a mixture of benzene and carbon tetrachloride). classified as blood and nerve poisons. These materials A solution of this material in the two named solvents include those compounds which poison the system and has the Chemical Warfare Service symbol CNB. which are capable of causing death in relatively low Another solution of CN and PS in chloroform bears the concentrations. Those which will be discussed are Chemical Warfare Service symbol CNS. Obviously carbon monoxide, (CO) ; arsine, (AsHa); and hydrogen this latter solution would combine the effects of the cyanide, (HCN). These materials all have relatively two agents which i t contains. Brombenzyl cyanide low molecular weights and hence are rapidly dispersed. o .m a---n ex(CsHsCHBrCN)is also a tear gas and has the Chemical Their tactical use would d e ~ e n don out tin^ d~~-Warfare service symbol B B C ~This material melts at W note in the book, "Gas Warfare," by Brigadier General at 2250C' Its vapors have an odor likeWaitt, 250C. and states that the Japanese are reported to have used CDA sour fruit. It is soluble in many of Our common organic in shells and bombs against the Chinese. 0

tremely high concentration of the agent for a relatively short time period. Since all are extremely toxic in relatively low concentrations, it is readily seen that situations would occur in which these substances may be used to advantage. Carbon monoxide is a colorless, odorless gas having approximately the same density as air. It boils a t - 192'C. and freezes a t -205.7°C. Physiologically it combines with the hemoglobin of the blood, forming an addition compound which is more stable than the oxyhemoglobin compound. Thus an individual exposed to this gas actually suffocates for lack of blood oxygen even though he is living in an atmosphere containing an ample concentration of it. Due to its extremely low critical point, this gas could be retained in a liquid state only a t a very low temperature. Hence it could be used only as compressed gas in shells and cylinders. This would limit the quantity that could be placed on a target in any time interval. Arsine is also a colorless gas. I t melts a t - 113.5'C. and boils at about -55°C. I t has a nauseating garliclike odor in moderate concentrations, and when diluted is almost odorless, although still toxic. This gas is decomposed above 230°C. Thus it may be used in cylinder attacks (limited usage), in grenades, or in shells, provided the temperature resulting from the bursting charge does not cause excessive decomposition of the agent. The symptoms of arsine poisoning vary with the degree of exposure. Generally anemia develops with a progressive drop in the red blood cell count. Jaundice is evident in cases of moderate exposure. This agent has a very profound effect on the kidneys, forming some sort of mechanical block, so that the passage of urine is hindered. The casualty usually shows evidence of uremia, and often dies from this poisodng. Hydrogen cyanide (Prussic acid gas) is colorless and has an odor similar to bitter almonds. It boils a t 26OC. and freezes a t - 15'C. In closed spaces it is extremely toxic, but its dispersion is so rapid in the field that low, nonlethal concentrations are soon established. This 'pas , arrests the activity of all forms of l i v i n -~ matter by inhibiting oxidation. In high concentration it causes death with dramatic rapidity through paralysis of the respiratory center in the brain. In open warfare this gas soon diffuses so that it loses its effectiveness. Its tactical value can be seen by observation of its relatively high boiling point, in addition to its extreme toxicity in closed spaces, such as in dugouts, tanks, etc. Our standard gas mask canisters will give protection only for a short time to low concentrations of CO, AsH3, and HCN. A special canister which gives Protection against carbon monoxide contains a catalyst

which oxidizes the CO to COe. Another canister for protection against acidic toxic gases such as HCN, H a , etc., contains an alkali-impregnated absorption layer. A large-scale use of these blood and nerve poisons is unlikely but not impossible. In specific instances their use might be of tactical value. The means of laying down or dispersing the war gases depend on (1) the physical state of the agent, (2) the type of mission desired, (3) the persistency of the agent, and (4) terrain and weather conditions. Persistent and moderately persistent gases may be laid down by airplane spray, explosive land mines, artillery, or mortar fire. A combination of two or more of these methods may be used on certain specific targets. The nonpersistent gases, in which a high concentration of agent is laid down in a short time interval, may be dispersed by mortar fire or aerial bombs. Persistent gases are generally nsed to contaminate areas which our troops will not occupy for some days and also to deny the enemy the occupation of certain areas. Nonpersistent gases are nsed for their surprise effect upon the enemy in areas which may be occupied by friendly troops a short time later. The surprise factor is of great importance in obtaining the greatest number of casualties, and is dependent upon the ability of friendly troops to get a great concentration of agent on the enemy in a very short time. a


The photographs reproduced in this paper have been taken from the Chemical Warfare Service News Letter, and The Chemical Warfare Bulletin. BIBLIOGRAPHY

CHE~~ICAL WARFARE SCHOOL, Pamphlet Number 2. CHEMICALWARFARESERVICE,War Department Technical Manual 3-215. ''Militam Chemistnr and Chemical Aeents." CLAFLINAND HICKEY, h he mica^ idhntification of war iases." T Fvpu r r -", 7" 251 IlUA?) u"..-"V n r--., ,-"A",. AN, "Der Chemische Krieg," E. X. Mittler and Son. n. 1937. , "War Gases." Publishers. Inc.. New York, . Interscience . 1942. LEAKEAND MARSH,"The action of war gases," J. C H E EDUC., ~ zo, 339 (1943), "Medical Manual of Chemical Warfare,"Revised edition, Chemical Publishing Company. New York, 1942. CHEM, NICHOLSON, ,,Chemical agents as screening smokes,,, ED,,,, 20,499 (1943). PRENTISS,"Chemicals in War." McGraw-Hill Book Company, Inc., New York. 1937. symposium on civilian preparedness far warfare,w J, CHBM. EDUC..~ 0 , 2 6 3 ~ 8(1943). 6 WACHTEL,"Chemical Warfare," Chemical Publishing Company. Brooklyn, New York. 1941. w,,, , e ~ aWarfare," s Duell. Sloan and Pearce, New York 1942. --A