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GASES USED PRIMARILY AS HARASSING AGENTS
52. General description of harassing agents
53. Lachrymators or "tear gases"
55. Action of lachrymators on the body
56. Protection against lachrymators
57. Treatment of tear gas cases
58. Nasal irritants or "nose gases"
60. Action of nose irritant gases on the body
61. Protection against nose gases
62. Treatment of nose irritant cases
52. General description of harassing agents.
This group includes certain gases or irritant smokes which, as met with in the open field, cause symptoms of distress without any subsequent physical injury. Typical examples are the following:
(1) Lachrymators or "tear gases," such as:
EthyModo-acetate (K.S.K.),
Bromo-bertzyI-cyanide (B.B.C.), and
Chloro-aceto-phenone (C.A.P.).
(2) Nasal irritants or "nose gases," organic arsenical compounds such as: Diphenylamine-chloroarsine (D.M.), and Diphenyl-cyanoarsine (D.C.).The primary object in the employment of these compounds is to harass troops by causing acute, though temporary, distress, thereby compelling them to wear respirators, possibly for prolonged periods. This tends to reduce efficiency, and, if anti-gas training be defective, to have a lowering effect on morale; this applies particularly to the more insidious nasal irritants.
These harassing gases have several important features in common, viz. -
(i) Their action is selective, i.e. they only attack exposed sensory nerve endings or mucous membranes, such as those of the eye, the nasopharynx and the respiratory tract.
(ii) The effects of the lachrymators are immediate, but temporary. The nasal irritants have a delayed action of a few minutes when compared with the lachrymators, and the discomfort is more lasting; in each case, however, withdrawal from the hostile atmosphere is followed by recovery.
(iii) They are effective in extremely low concentrations, but they are never followed by permanent disabilities. It is very unusual to incur any physical injury from these irritating gases, though a rare case may be met with after an unusually heavy dosage.
53. Lachrymators or "tear gases."
There are many compounds, both liquid and solid, which may be used as lachrymators in wartime. The following are typical examples:
(a) Ethyl-iodo-acelate.- A dark brown, oily liquid with a smell resembling that of "peardrops." Its high boiling point (1800 C. or 356) F.) and comparatively low vapour pressure ensure for it a certain degree of persistence on the ground.
(b) Bromo-benzyl-cyanide.- In the pure state this is a yellowish crystalline solid, stable at ordinary temperatures and melting at 24.80 C. (74.60 F). In the crude form, as employed in war B.B.C. is a heavy, oily, yellow liquid with a penetrating bitter-sweet smell. The liquid boils at 2420 C. (467.60 F.); it is more stable, and has a lower vapour pressure than ethyl-iodo-acetate, hence it persists longer than the latter as an effective lachrymator when spread on the ground.
(c) Chloro-aceto-phenone. - A colourless, crystalline solid melting at 540 to 590 C. (129.2 to 138.20 F.) and boiling at 2450 C. (4730 F.). Though only sparingly soluble in water, it dissolves readily in all the organic solvents. Chloro-aceto-phenone is a very stable compound which does not decompose on heating or detonation; its lachrymatory effects, however, are soon lost by reason of the condensation of the substance to the solid, inert state soon after the initial dispersion, and it is therefore classed among the non-persistent gases. It is used extensively in gas training schools.
The liquid lachrymators may be dispersed by shell or bomb, or by mechanical spraying for purposes of ground contamination. The solid C.A.P. can be dispersed from generators by means of heat, or it may be sprayed, in solution, from the exhaust pipes of internal combustion engmes. It is, however, unsuitable for use in shell.
For training purposes, small capsules containing solid C.A.P. are heated over a flame to evolve the gas, while in certain countries effective use of this compound is made by the police against mobs; a variety of more or less harmless weapons such as lachrymatory pistols and hand bombs are employed for this purpose.
55. Action of lachrymators on the body.
Exposure to any of these lachrymators gives rise to an immediate, acute and localized irritation of the sensory nerve-endings on the corneal and conjunctival surfaces, which may vary from a mild irritation to an intense stinging sensation according to the concentration. Through reflex action, this is followed by profuse watering of the eyes and spasm of the eyelids, and the latter may be so acute as to render it impossible to keep the eyes open.
With a rise in the concentration of the vapour, further effects may make their appearance. The irritant action of the gas on the respiratory passages and lungs produces a burning feeling in the throat and discomfort in the chest, and, if the exposure be continued, nausea and vomiting may result.
Ethyl-iodo-acetate is less irritating to the respiratory tract than chloro,-aceto-phenone. The latter however, possesses the characteristic attribute, absent in the case of the liquid lachrymators, of irritating the bare skin, especially if it be hot and moist.
As a rule, persons exposed to lachrymators never exhibit more severe symptoms than those described above, as the very high concentrations necessary to produce lung lesions are not met with in the field. In confined spaces, however, where accidental splashes of the actual liquid on the skin may occur, or the inhalation of a high concentration may be experienced, more severe results may be expected. These vary from severe conjunctivitis, with tracheitis and bronchitis from the effects of the vapour, to blistering of the skin, keratitis and corneal opacities after contamination with the liquid.
The rare fatalities that occurred in the Great War were characterized by a severe pulnionary cedema following the accidental inhalation of re concentrations of the gas released by the explosion of lachrymatory bombs or shells close to the victim.
56. Protection against lachrymators.
The respirator affords complete protection to both eyes and lungs against all concentrations of tear gases likely to be met. The use of goggles alone is not recommended, as, in addition to the liability of leakage and constant dimming, they offer no protection to the respiratory tract.
The irritant action of C.A.P. and other solid lachrymators on the hot, moist skin is not sufficiently intense in temperate climates to necessitate special protective garments.
57. Treatment of tear gas cases.
In the great majority of cases, adjustment of the respirator win suffice to alleviate the symptoms, and, usually, to clear up the condition completely. Experience has shown that even after severe exposures all symptoms disappear within 12 hours. No treatment is usually necessary, and no after-effects follow exposure. In the rare cases where acute conjunctivitis or respiratory affections develop, treatment should be symptomatic and follows general principles. If the eyes be contaminated by the actual liquid from aerial sprays, bursting bombs, etc., lavage of the eyes with normal saline will be necessary.
58. Nasal irritants or "nose gases."
These sensory irritants are solid organic arsenical compounds which can be dispersed by heat or detonation in the form of a very fine, almost invisible, particulate cloud or smoke.
The object underlying their original employment in the Great War was to penetrate the respirator container in use at that time, in the belief that the distressing symptoms following even a brief exposure would induce men to discard their respirators as useless; this would expose them to the effects of lethal gases, such as phosgene, which were often released simultaneously. The nasal irritants did not meet with any striking success because the methods in use at that time for the release of the gas were unsatisfactory.
The following are typical examples of the nasal irritants:
(a) Diphenylamine-Chloroarsine.- A yellow, almost odourless, crystalline solid melting at 1950 C. (4730 F.) and boiling (with decomposition of the compound) at 4100 C. (7700 F.) at ordinary atmospheric pressure; insoluble in water, and difficult to dissolve in the ordinary orgamic solvents.
(b) Diphenyl-cyanoarsine -A colourless crystalline solid, ahnost entirely odourless, with a melting point of 330 C. (91.40 F.) and boiling at 3460 C. (654.80 F.) at ordinary atmospheric presstife ; almost insoluble in water, but dissolving readily in oils and in organic solvents.
These compounds are solids at ordinary temperatures, but when heated or detonated they are vaporized, without decomposition, in the form of an almost invisible cloud of minute particles which remain suspended in the air.
Heat may be employed by means of special incendiary generators which are placed in position by hand or dropped from vehicles, or the solid compound may be incorporated in shell. By these methods it is possible to emit, over a wide front, a cloud of extremely fine particles of these irritant arsenical compounds.
60. Action of nose irritant gases on the body.
The main feature of these arsenical irritants is their power of causing violent sensory irritation in man even though present in extremely low concentrations. The effectiveness of the arsenical gases depends on the amount inhaled before symptoms (which are delayed in onset for some minutes) make themselves felt. Even if the affected person withdraws from the
poisonous atmosphere (or puts on his respirator) directly the irritant effects are felt, the symptoms continue to increase in severity for some time before they begin to subside. Unlike the tear gases, therefore, whose sensory effects are immediate, but disappear rapidly on adjustment of the respirator, the arsenical irritants are characterized by an mcre~ in the severity of the initial symptoms after adjusting the respirator or leaving the gas-laden atmosphere. This delayed action of the arsenicals and the subsequent aggravation of symptoms constitute their chief danger in the case of ill-trained personnel, as they may engender distrust in the respirator.
The symptoms are characteristic, and consist of acute pain in the nose and accessory sinuses with a sense of "fullness" in the head and with repeated sneezing (hence the term "sternutators" applied to these gases). A burning sensation in the throat, and one of tightness and pain in the chest, also a feeling of grittiness in the eyes with pain and lachrymation, and aching of the gums are common, while salivation, with nausea or even vomiting, are important symptoms. Acute mental distress is very marked in severe cases, in which the patients feel and look utterly miserable. This condition of intense discomfort is very alarming to the inexperienced.
The irritant effects are transitory, and affected men should not leave their units as the symptoms usually disappear within one to four hours. Even in severe cases no lasting organic lesion is likely to follow exposure to these gases in the open.
61. Protection against nose gases.
The respirator charcoal, so effective in arresting the lethal gases, has little protective value against the particulate clouds of these arsenical compounds. Special filtering devices must be employed to trap the arsenical dust in the air, and all modern respirators for use against war gases give adequate protection.
Symptoms of true arsenical poisoning may, occur through men using water drawn from shell craters contaminated with these arsenicals. The arsenic content in these craters may be very high, and men have been known to suffer from dermatitis after shaving with water drawn from them. It is important, therefore, that stringent orders be issued that no water from shell craters be employed for drinking, cooking or washing.
62. Treatment of nose irritant cases.
In the great majority of cases a brief period of rest is the most that is required. In a few exceptionally severe cases, however, pain may call for relief from the Medical Officer, when the inhalation of a little chloroform will be found of transitory assistance. A five per cent. solution of sodium bicarbonate for nasal irrigation or as a gargle will help to allay the irritation of the nose and throat.
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