Protection of Food Against Chemical Attack' MORRIS B. JACOBS Department of Health, New Y o r k , New Y o r k good protection against contamination from the liquid agent except when subjected to direct splashes. They also provide good protection against vapor contamination except under long exposures. Foods packaged with several covers, such as layers of dense paper, wax paper, cardboard, greaseproof paper, cellophane, metal foil, and other materials, provide good protection against poison gas vapor and liquid for several hours or days if the seams, edges, and comers are well made and intact. These are the most vulnerable parts of the package to the penetration of chemical agents. Laminated bags consisting of a number of plies have been developed which offer excellent protection against chemical attack. These packages do not have the physical strength of those in the first group, however. Multilayer packages such as can be obtained by using asphalts or microcrystalline waxes for laminating purposes are valuable (11). Cellophane to cellophane (12), and cellophane to glassine to strong dense paper are examples. Other types of packages produced with papier-mach6, oilskin, latex, etc., can give fairly good protection if used in more than one layer. It is surprising to note the protection against gas given by the ordinary cereal package (9). PACKAGING Little or no Protection. Ordinary wooden or cardWe can classify the means of packaging food to board boxes provide some protection against poison protect i t against war gases into three main groups: gas vapor, particularly if they are lacquered, but offer (1) those which provide complete protection against practically no protection against the liquid. Paper conboth poison gas vapor and liquid chemical agent, (2) tainers similar to ordinary paper bags, or burlap, canthose which provide good protection against poison gas vas or Hessian sacks offer no protection against either vapor or liquid chemical agent, and (3) those which vapor or liquid contamination unless specially treated. provide poor or no protection against chemical attack. Protective Materials. The various types of protecCumfilete Protection. In the first group we can tive material that may be used have been mentioned in place all foods packaged in hermetically sealed con- the previous sections and they may be classified as tainers, such as canned or jarred goods. Foods pack- metal containers, glass containers, and materials which aged in tin, or in glass or glazed earthenware with can be used to make multilayer packages. Among impervious screw caps or similar closures, and sealed these we can mention rubber latex and synthetic rubmetal drums or sealed metal-lined cases, comprise most bers, metal foil, cellophane and other cellulose derivaof this group. Sealed wooden barrels used for the tives, synthetic plastics, and resins. Among other transportation and storage of liquids also offer com- substances suggested are polyvinyl alcohol, and gelatiuplete protection against vapor contamination and al- glycerol treated with formaldehyde or chromates to most complete protection against liquid agents, ex- make it water-insoluble. Under present circumstances, cept in the case of prolonged contact with liquid poison metal foils, rubber latex, and synthetic rubbers are gas. not available in substantial quantities for civilian use. Good Protection. In a similar manner, metal cans The other materials may be used, but are limited in with friction covers, or glass or glazed earthenware quantity because of the war emergency. It is well to vessels sealed with paper caps such as the common milk note that discretion must be exercised in the choice of bottle. or similar bottles with cork stoppers, provide packaging materials. Thus, cellulose wrappings made from cellulose acetate, cellulose nitrates, and cellulose 1 Paper presented in the "Symposium on Civilian Preparedare satisfactory, while those based on benzyl cellulose ness for Chemical Warfare" at the 105th meeting of the American are less satisfactory. In a similar manner, not all synChemical Society in Detroit, Michigan, April 12-16,1943. 282
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HE British Ministry of Food (10) has as the subtitle
of its . pamphlet "Food and Its Protection Against Poison Gas" the following: The Conservation of Food Is Second Only to the Preservation of Life. We can realize the importance of that statement. When war was declared on December 8, 1941, i t was a common conception that we had an abundance of food and that a t no time would it be necessary for us to worry about our supply. The manpower shortage and rationing have taught us that i t is necessary for us to conserve this supply for the present emergency and to help our allies. One of the aims of chemical attack is to make food and similar stores unfit for avilian as well as militarv use. The best way to obviate the need for salvaging foods after gas attack is to protect them from contamination before attack. In considering the protection of foods we must take into account the principal types of pollution: contamination due to poison gas vapor or to liquid chemical agent. The measures to be used for the protection of food against chemical attack can be considered in two categories; namely, proper packaging and proper storage.
283 thetic resins or plastics have equal value as protective materials. Some plasticizers, used in the manufacture of synthetics, actually can transport liquid or vapor poison gas through the packaging material. Some of these materials, and a method for testing the impermeability of the material to a chemical agent are discussed by Katz (7). STORAGE
Protective Measures for Large Quantities of Food. The degree of protection of food from liquid gas, and to a lesser extent from its vapor, is of great importance for large quantities of foodstuffs. This will depend generally on the size of the food stack, on the type of container, if any, and on the system of stacking. Closely stacked piles such as those often found in warehouses are not readily penetrated, even by vapors, and what vapor does penetrate the pile is largely absorbed on the outside of the individual packages. The protective measures to be used for safeguarding bulk stores of food in warehouses, docks, and other places where such large stores are held may be summarized as follows (5): 1. Foods in containers or wrappings which afford little or no protection against chemical agents should not be stored on the top floors, or in the basements of buildings, because such locations are most vulnerable to chemical attack. 2. Covers made of canvas impregnated with drying oils, plastics, synthetic resins, rubber, asphalt, and similar materials, water-repellent duck covers, impervious tarpaulins, rubber sheeting, if available, and oilskins, are probably the best means for covering stocks of foodstuffs in packages. They give good protection against oily splashes of chemical agents and the packages protect the foods against vapor contamination. 3. These sheetings and coverings should cover the piles as closely as possible but, when inconvenient, they should be hung as screens by means of hooks orframes. Where free circulation of air is necessary for proper storage, as in the case of fresh fruit in crates, these covers should be arranged so that they can be readily pulled into position as soon as an air raid warning is given. 4. Ordinary sacking can also be used to provide covering. Such materials, as mentioned above, provide little protection against the vapor of poison gas but they do reduce the contamination resulting from splashes. 5. Foods stored in freezers or refrigerated rooms need no additional protection, provided the doors are reasonably air tight and precautions have been taken against blowing or drawing the poison gas into the refrigerator by the ventilating system. 6. Food should be stored in close stacks and should not be permitted to lie scattered about the warehouse floors. Such stacking affords good protection for the interior of the pile. It is advisable not to break into
these bulk stocks unless they are to be subdivided for sale (2). 7. Avoid using food for display purposes and keep foods in containers so that they will not be exposed. This protects them from other forms of attack also. Similar precautions should be observed on a smaller scale, of course, by retail food stores, institutions, restaurant commissaries, and hotels where relatively large stores of food are held. Protective Measures for Food i n the Home. To protect food a t home, place as many as possible of the bottles, jars, canned goods, or other sealed containers inside closets with wooden doors or in strong wooden boxes with tight-fitting covers. Store most of your food in tin cans with close fitting covers or in bottles with plastic screw caps. This is especially important for foods such as sugar, flour, or cereals, which are generally bought in easily penetrable coverings. The domestic refrigerator or ice box is sufficiently air tight to provide a gasproof storage place. SALVAGE OF FOODS
Effect of War Ghses on Foods (5). In order to evaluate the possibility of salvaging food stocks, we must understand how they are damaged. The extent of damage to foods contaminated by chemical warfare agents will depend on the chemical and physical properties of the war gases and on the food itself, as well as on the degree of exposure of the food to the war gas. Foods and war gases may be put into two main groups by a consideration of these properties. All foods contaminated by arsenicals and white phosphorus, and fatty foods contaminated by nonarsenical vesicants like mustard gas and the nitrogen mustards, form the poisonous group. Foods contaminated with other agents may be considered relatively nonpoisonous, especially after adequate salvaging operations. Foods absorb chemical agents by solution in the water or fat they contain or adsorb these agents on their solid surfaces. Either process may be followed by a reaction which involves some degree of decomposition of the chemical agent. The principal chemical reaction is hydrolysis. After hydrolysis, in some instances the chemical agent will lose its toxic properties, as is the case with mustard gas or phosgene, in which cases innocuous substances are formed. In other instances, the hydrolytic products are still toxic. Such reactions may be illustrated by Lewisite which yields a vesicant arsenical solid on hydrolysis. The chemical reagent may react with the foodstutf itself. Thus, mustard gas reacts with the protein of meat to form a film which prevents further penetration of the food by the chemical agent. Since most war gases are organic substances they are more soluble in fatty foods than in foods containinp large amounts of water. Solution of chemical agents in fats is seldom followed by any chemical reaction cornoarable to that of hvdrolvsis or coaeulation. , , Consequently, once the surface of a fatty food is
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seriously contaminated, the food is generally rendered unfit for human consumption. Guide for Saluage of Foods. The following simple rules should act as a guide in the salvaging of foods: 1. Foods seriously contaminated with mustard gas or nitrogen mustards, particularly fatty foods, should be discarded. 2. All arsenical war gases are systemic poisons; therefore, foods contaminated with them should be destroyed. 3. Foods seriously contaminated with liquid nonpersistent agents or less toxic agents should also be discarded, exceDt in a serious emergencv when salva~e " shouldbe attempted. 4. Foods contaminated only slightly with nonpersistent agents or less toxic agents may be salvaged. 5. Foods contaminated with solid white phosphoms are poisonous and must be discarded. 6. Foods which are discarded for use for human beings may possibly be reclaimed for industrial purposes. 7. If one is doubtful about the wholesomeness of any food, discard or destroy it. The methods which can be employed for the salvage of foods are: (a) Aeration and ventilation. (b) Cutting away contaminated portions. (c) Heating and cooking. (d) Washing. (e) Decontamination of containers. V) Other methods. Aeration and Ventilation. Most foods can be salvaged by airing, after removing as much as possible of the heavily contaminated portions. All aeration should take place under conditions which permit a slight draft across as much surface as possible of the polluted food or package. Increase in temperature will hasten evaporation of the chemical agent and will assist in the aeration process but heating is not always permissible. Cutting Away Polluted Portiuns. The general rule to follow is to cut away sufficient depth of the foodstuff to be certain that no poison gas has penetrated beyond. In most instances one-half to one inch will suffice,particularly if salvage operations have started soon after exposure. The bleaching action of phosgene is a guide for the depth to which to cut foods contaminated by that agent. Mustard gas drops on meat will penetrate the flesh about 4 to 5 mm. in 48 hours (13). Thus carcass meat contaminated with this agent can be used if the polluted parts are cut away and the rest is thoroughly cooked. Animals may be used for food even after exposure to vesicants and lung irritant gases, if they are slaughtered in an approved manner, and the viscera, the hide, and the fatty tissue immediately beneath the skin are discarded. Heating and Cooking. As previously explained, some war gases are readily volatile and others hydrolyze on boiling with water to relatively harmless substances. Hence some contaminated foods can be salvaged by u
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heating and cooking-in particular, foods contaminated with non-persistent agents like phosgene. For instance, fresh vegetables and fruits and dried fruits may be salvaged by cooking after contamination with phosgene vapor. However, i t is to be noted that food seriously contaminated with chloropicriu cannot be salvaged by cooking, since this chemical agent is not hydrolyzed by water. Washing. Reclamation of foods by wishing is a limited process, because once the liquid agent has penetrated the food, washing has little effect on its removal. Vegetables which have been exposed to vapor contamination may a t times be salvaged by washing. Fish contaminated by vapor, or exposed to spray while packed in ice, may be reclaimed by washing with a hypochlorite solution. Decontamination of Containers. Foods packed in hermetically sealed containers will be protected from poison gas, but the container itself will be polluted if exposed. I t must therefore be decontaminated. If polluted only by vapor, washing and aeration may be sufficient. If exposed to liquid agent, the container must be decontaminated by use of hypochlorite solution or by use of hot water, neutralizing substances like sodium carbonate, and a wetting agent such as Aerosols OT and OS ( I ) , or sulfonated corn oil. Labels must be removed and the package relabeled. Other Methods. In cases in which toxic smokes settle on packaged articles, i t should be possible to remove the dust by means of an efficient vacuum cleaner. It may be possible to reclaim the interior of bags containing powdered foods by immersing the bag in water to form a paste of the outer layers of the food against the bag, and then removing the inner contents by suction. Foods which are wholesome but whose palatability has been seriously affected may be salvaged by diluting them with similar uncontaminated foods. Decontamination of Water. It would be difficult to pollute the water supply of a large city to an extent sufficient to render the water harmful, because of the enormous amounts of chemical agent needed for this purpose. Furthermore, many of the chemical agents are relatively insoluble in water. Others react and hydrolyze to form innocuous compounds. Still others react with some of the compounds in the water to form harmless substances. However, the portion of the reservoir subjected to attack must be considered in evaluating the effect on pollution of the water supply. In any event, if the water purification system of the city is operating, the processes of coagulation, sedimentation, filtration, chlorination, etc., with the accompanying addition of alum and lime, ferrous sulfate and lime, activated carbon, ammonia, chlorinated lime, liquid chlorine, or even ozone, would tend to remove the war gases as a routine part of the potable water treatment process. Water supplies obtained from wells, cisterns, etc., and used as a private water supply, must be analyzed by the proper authorities if any suspicion of gas pollution exists.
SAMPLING
Purpose. The fundamental purpose of sampling, and for that matter, of field testing, is to enable the gas reconnaissance agent: (1) to detect the presence of gas, (2) to recognize its physiological classification, (3) to determine the concentration and potential hazard, (4) to ascertain the extent of the polluted area, (5) to aid in selecting the best means of decontamination, and (6) following decontamination to determine its completeness prior to reoccupancy. The sampler should he adequately clothed and equipped. The Chemical Warfare Service requests that samples be sent to their laboratories in the appropriate region. All pertinent information concerning any sample should be sent to the laboratory to which the sample is being shipped. Type of Sample. It will generally be necessary to take only four types of samples; namely, samples of air, water, food, and materials. In contradistinction to ordinary sampling, it is unnecessary to obtain a socalled representative sample. Obtain the most polluted sample possible. Air Sam$ling. Air samples may he taken by using a gas collector or by passing the air through an ahsorbent or adsorbent, or through an absorbing solution (4).
Sampling Water, Food, and Materials. To sample water, food, and materials, wide mouth screw cap bottles should be used. The exact details are described by Jacobs (5). It will generally be best to obtain samples from the surface of foodstuffs and from the inner portions, in order to obtain some knowledge of the extent to which a chemical agent has penetrated. One of the difficulties is to sample the food in such a way that clean food is not contaminated by the sampling equipment previously used for polluted food. It is necessary in the case of food sampling to obtain samples of the unpolluted food as well as of the polluted portion. WATER, MILK, AND FOOD (6) Necessity fur Being Alert. It is necessary for us to guard ourselves not only against chemical attack from without but also from chemical attack from within our ranks. Chemical sabotage is the term applied to the addition of chemical poisons to water or foods, such as milk, which are distributed in hulk quantities from central points. Chemical and bacteriological analysis will safeguard us against such forms of attack. As an example of the possibilities of such attack one can cite the case of one worker, a typhoid carrier, who caused 5000 cases and 500 deaths in Montreal in 1927 through contamination of a supply of pasteurized milk. Organoleptic Analysis. An organoleptic analysis, (3) or a sensory analysis, is one which is made by use of our senses, principally sight, odor, and taste. Using milk as an example, we can illustrate the subjective method. All personnel handling milk must be cautioned to he on the alert for any deviation from the normal in the appearance, odor, or taste of the milk CHEMICAL SABOTAGE OF
a t any stage of its handling. If an off-color, off-odor, or off-taste is noted, a report to a superior should he made immediately. Personnel must be taught to smell and taste cautiously. In order to make a smell test, s n B once or twice gently and try to recall the odor. In order to make a taste test, roll a small amount of milk over the tongue; do not swallow, but discard. Gross contamination of milk will-often be readily detected by these simple tests. The value of organoleptic analysis as an aid in the detection of poisons should neither be underestimated nor overestimated. Thus, for instance, poisonous suhstances added to milk may be sufficiently acid to curdle milk and so will readily be detected. Or another poison may have sufficientcoloring power to give the milk an off-color. These are examples of information to be obtained by noting the appearance of the milk. So too, if a poison having a characteristic odor such as a phenol, hydrogen cyanide, or nitrobenzene, is added, attention to the off-odor will assist in the detection. Any bitter taste or other off-taste in milk should he noticed. Among the poisons which have a very bitter taste are piaotoxin, colchicin, picric acid, veronal, strychnine, brucine, and similar substances, especially alkaloids. General Tests on Waler. Our principal means of detecting the addition of poisons to water is based upon the change in the reactions of the water. The tests commonly used are the organoleptic tests mentioned previously and chemical determinations of the pH, alkalinity, chloride content, chlorine demand, and oxygen consumption. These general tests will almost invariably enable us to detect harmful additions of poisonous materials. Special Tests. The special tests to be performed in the field (6) (8), which will enable us to detect the common poisons may be tabulated as follows: INORGANIC POISONS Srbrlonca
Test
White or ycllow phornhorua Cyanidu Borate3 Oxidizing agenfcchlorine, hyp* chlorite., nitrites, peroxides. iodates, ete. Nitrate4 Fluorides Heavy metals Arsenic and antimony Selenium and tellwivm
AgNOi tut paper Pinie acid test paper Tumcrie test paper Starch-iodide test Diphenylamine test Sodium dreonium alizarinate paper Sulfide test Hoffman t u t Reduction with svlfw dioxide and bydrorylamine hydrochloride
ORGANIC POISONS Sub3lrlnnrc Phenol, eresol, trieresyl phosphate Formaldehyde O d i c acid Alkaloidal nnd nonalkaloidal poisons Glumside. nnd saponins
Test Gibb'~reagent-2,6-dibromoqoiuiouiuichIoroiiidd Rosaoiline-sulfitc test Ethyl ether extraction and ealeium oxalate pre Cipitation It would be most unlikely fhst there subrtances muld be used in large quantities because of price and unavailability. Note organolcptie methods. Extraction method. Ditto above. Saponins might impart e p ~ ~ i i t t t t foam
These field tests should be verified in the laboratory.
LITERATURE CITED
BRADLEY,CASSADAY,MOORE,AND MOORE,C h . Eng. N m s , 21, 373 (1943). CADDICK. "Decontamination of Foodstuffs." Sanitary Publishing Company, London. 1941. JACOBS, "Chemical Analysis of Foods and Food Products," D. Van Nostrand, New York, 1938. JACOBS. "Analytical C h y i s t r y of Industrial Poisons. Hazards, and Solvents. Interscience Publishers, New York. 1941. J~cpss,"WarCases, Tbeu Identification and Decontaminatron, Intersc~encePubhshers, New York, 1942.
AND S T E E B ~ "Technical S, Manual for Gas Reconnaissance Officers." Department of Health, City of New
JAMBS
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Vnrk . . .-, lo&? . .-
KATZ.Ind. Eng. Chem., 35, 20 (1943). KORFF AND KAPLAN, Am. I.Pub. Health, 32,1110 (1942). Ind. Eng. Chen., 35, 16 (1943). MELSON, Ministry of Food (Brit.), "Food and Its Protection Against Poison Gas," London. 1941. Proceedings, Inst. Food Technologists, 121 THROCKMORTON, ,A"-,. WENDLER, P~o~eedings. Inst. Food Technologists, 344 (1942). WOOLDRIDGE, vet. Record. 53, 661 (1941).
