Human Foods and Their Nutritive Value Part 15

263. Importance.--Water is one of the most essential food materials.

It enters into the composition of the body, and without it the nutrients of foods would be unavailable, and life could not be sustained. Water unites chemically with various elements to form plant tissue and supplies hydrogen and oxygen for the production of organic compounds within the leaves of plants. In the animal economy it is not definitely known whether or not water furnishes any of the elements of which the tissues are composed, as the food contains liberal amounts of hydrogen and oxygen; it is necessary mainly as the vehicle for distributing nutrients in suspension and solution, and as a medium in which chemical, physical, and physiological changes essential to life processes take place. From a sanitary point of view, the condition of the water supply is of great importance, as impure water seriously affects the health of the consumer.[87]

264. Impurities in Water.--Waters are impure because of: (1) excessive amounts of alkaline salts and other mineral compounds; (2) decaying animal and vegetable matters which act chemically as poisons and irritants, and which may serve as food for the development of objectionable bacterial bodies; and (3) injurious bacteria. The most common forms of impurities are excess of organic matter and bacterial contamination. The sanitary condition of water is greatly influenced by the character of the soil through which it flows and the extent to which it has been polluted by surface drainage.[88]

[Ill.u.s.tration: FIG. 61.--DIRT AND IMPURITIES IN A SURFACE WELL WATER.]

265. Mineral Impurities.--- The mineral impurities of water are mainly soluble alkaline and similar compounds dissolved by the water in pa.s.sing through various layers of soil and rock. When water contains a large amount of sodium chloride, sodium sulphate or carbonate, or other alkaline salts, it is termed an "alkali water." Where water pa.s.ses through soil that has been largely formed from the decay of rocks containing alkaline minerals, the water dissolves some of these minerals and becomes alkaline. The kind of alkali determines the character of the water; in some cases it is sodium carbonate, which is particularly objectionable. The continued use of strong alkali water causes digestion disorders, because of the irritating action upon the digestive tract.

Hard waters are due to the presence of lime compounds. In regions where limestone predominates, the carbon dioxid in water acts as a solvent, producing hard waters. Waters that are hard on account of the presence of calcium carbonate give a deposit when boiled, due to liberation of the carbon dioxid which is the material that renders the lime soluble.

Calcium sulphate, or gypsum, on the other hand, imparts permanent hardness. There is no deposit when such waters are boiled. A large number of minerals are found in various waters, often sufficient in amount to impart physiological properties. Water that is highly charged with mineral matter is difficult to improve sufficiently for household purposes. About the only way is by distillation.[89]

266. Organic Impurities.--Water that flows over the surface of the ground comes in contact with animal and vegetable material in various stages of decay, and as a result some is dissolved and some is mechanically carried along by the water. After becoming soluble, the organic matter undergoes further chemical changes, as oxidation and nitrification caused by bacteria. If the organic matter contain a large amount of nitrogenous material, particularly of proteid origin, a series of chemical changes induced by bacterial action takes place, resulting in the production of nitrites. The nitrifying organisms first produce nitrous acid products (nitrites), and in the further development of the nitrifying process these are changed to nitrates. The ammonia formed as the result of the decomposition of nitrogenous organic matter readily undergoes nitrification changes. Nitrates and nitrites alone are not injurious in water, but they are usually a.s.sociated with objectionable bacteria and generally indicate previous contamination.[90]

267. Interpretation of a Water a.n.a.lysis.--"Total solid matter"

represents all the mineral, vegetable, and animal matter which a water contains. It is the residue obtained by evaporating the water to dryness at a temperature of 212 F. Average drinking water contains from 20 to 90 grains per gallon of solid matter. "Free ammonia" is that formed as a result of the decomposition of animal or vegetable matter containing nitrogen. Water of high purity usually contains less than 0.07 parts per million of free ammonia. "Alb.u.minoid ammonia" is derived from the partially decomposed animal or vegetable material in water. The greater the amount of nitrogenous organic impurities, the higher the alb.u.minoid ammonia. A good drinking water ought not to contain more than 0.10 part per million of alb.u.minoid ammonia. An abnormal quant.i.ty of chlorine indicates surface drainage or sewage contamination, or an excess of alkaline matter, as common salt. Nitrites should not be present, as they are generally a.s.sociated with matter not completely oxidized. Nitrites are usually considered more objectionable than nitrates; both are innocuous unless a.s.sociated with disease-producing nitroorganisms.

268. Natural Purification of Water.--River waters are sometimes dark colored because of large amounts of dissolved organic matter, but in contact with the sun and air they gradually undergo natural purification and the organic matter is oxidized. However, absolute reliance cannot be placed upon natural purification of a bad water, as the objectionable organisms often have great resistive power. There is no perfectly pure water except that prepared in the chemical laboratory by distillation.

All natural waters come in contact with the soil and air, and necessarily contain impurities proportional to the extent of their contamination.

269. Water in Relation to Health.--There are many diseases, of which typhoid fever is a type, that are distinctly water-born. The typhoid bacilli, present in countless numbers in the feces of persons suffering or convalescent from typhoid fever, find their way into streams, lakes, and wells.[91] They retain their vitality, and when they enter the digestive tract of an individual, rapidly increase in numbers. Numerous disastrous outbreaks of typhoid fever have been traced to contamination of water. Coupled with the sanitary improvement of a city's water supply, there is diminution of typhoid fever cases, and a noticeable lowering of the death rate. Many cities and villages are dependent for their water upon rivers and lakes into which surface drainage finds its way, with all contaminating substances. Mechanical sedimentation and filtration greatly improve waters of this cla.s.s, but do not necessarily render them entirely pure. Compounds of iron and aluminium are sometimes added in small amounts, under chemical supervision, to such waters to precipitate the organic impurities. Spring waters are not entirely above suspicion, as oftentimes the soil through which they flow is highly polluted. All water of doubtful purity should be boiled, and there are but few natural waters of undoubted purity. There is no such thing as absolutely pure water in a state of nature. The mountain streams perhaps approach nearest to it where there are no humans to pollute the banks; but then there are always the beasts and birds, and they, too, are subject to disease. There are very few waters that at some time of the year and under some conditions are not contaminated with disease-producing organisms. No matter how carefully guarded are the banks of lakes furnis.h.i.+ng the water supply of cities, more or less objectionable matter will get in. In seasons of heavy rains, large amounts of surface water enter the lakes, carrying along the filth gathered from many acres of land drained by the streams entering the lakes. Some of the most serious outbreaks of typhoid fever have come from temporary contamination of ordinarily fairly good drinking water.

In general, too little attention is given to the purity of drinking water. It is just as important that water should be boiled as that food should be cooked. One of the objects of cooking is to destroy the injurious bacteria, and they are frequently more numerous in the drinking water than in the food.

The argument is sometimes advanced that the mineral matter present in water is needed for the construction of the bone and other tissues of the body, and that distilled water fails to supply the necessary mineral matter. This is an erroneous a.s.sumption, as the mineral matter in the food is more than sufficient for this purpose. When water is highly charged with mineral salts, additional work for their elimination is called for on the part of the organs of excretion, particularly the kidneys; and furthermore, water nearly saturated with minerals cannot exert its full solvent action.

In discussing the immediate benefits resulting from improvement of water, Fuertes says:[92]

"Immediately after the change to the 'four mile intake' at Chicago in 1893, there was a great reduction in typhoid. Lawrence, Ma.s.s., showed a great improvement with the setting of the filters in operation in September, 1893; fully half of the deaths in 1894 were among persons known to have used the unfiltered ca.n.a.l water. The conclusion is warranted that for the efficient control of the death rate from typhoid fever it is necessary to have efficient sewerage and drainage, proper methods of living, and pure water. The reason why our large cities, which are all provided with sewerage, have such high death rates is therefore without doubt their continuance of the filthy practice of supplying drinking water which carries in solution and suspension the was.h.i.+ngs from farms, from the streets, from privies, from pigpens, and the sewage of cities.... And also we should recognize the importance of flies and other winged insects and birds which feed on offal as carriers of bacteria of specific diseases from points of infection to the watersheds, and the consequent was.h.i.+ng of newly infected matter into our drinking water by rains."

There is a very close relations.h.i.+p between the surface water and that of shallow wells. A shallow well is simply a reservoir for surface water acc.u.mulations. It is stated that, when an improved system of drainage was introduced into a part of London, many of the shallow wells became dry, indicating the source from which they received their supply. Direct subterranean connection between cesspools and wells is often traced in the following way: A small amount of lithium, which gives a distinct flame reaction, and a minute trace of which can be detected with the spectroscope, is placed in the cesspool, and after a short time a lithium reaction is secured from the well water.

Rain water is relied upon in some localities for drinking purposes. That collected in cities and in the vicinity of barns and dwellings contains appreciable amounts of organic impurities. The brown color is due to the impurities, ammonium carbonate being one of these. There are also traces of nitrates and nitrites obtained from the air. When used for drinking, rain water should be boiled.

270. Improvement of Waters.--Waters are improved by: (1) boiling, which destroys the disease-producing organisms; (2) filtration, which removes the materials mechanically suspended in the water; and (3) distillation, which eliminates the impurities in suspension and solution, as well as destroys all germ life.

271. Boiling Water.--In order to destroy the bacteria that may be in drinking water, it is not sufficient to heat the water or merely let it come to a boil. It has been found that if water is only partially sterilized and then cooled in the open air, the bacteria develop more rapidly than if the water had not been heated at all. It should boil vigorously five to ten minutes; cholera and typhoid bacteria succ.u.mb in five minutes or less. Care should be taken in cooling that the water is not exposed to dust particles from the air nor placed in open vessels in a dirty refrigerator. It should be kept in perfectly clean, tight-stoppered bottles. These bottles should be frequently scalded.

Great reliance may be placed upon this method of water purification when properly carried out.

272. Filtration.--Among the most efficient forms of water filters are the Berkefeld and Pasteur. The Pasteur filter is made of unglazed porcelain, and the Berkefeld of fine infusorial earth (finely divided SiO_{2}). Both are porous and allow a moderately rapid flow of water.

The flow from the Berkefeld filter is more rapid than from the Pasteur.

The mechanical impurities of the water are deposited upon the filtering surface, due to the attraction which the material has for particles in suspension. These particles usually are the sources of contamination and carry bacteria. When first used, filters are satisfactory, but unless carefully looked after they soon lose their ability to remove germs from the water and may increase the impurity by acc.u.mulation. Small faucet filters are made of porous stone, asbestos, charcoal, etc. Many of them are of no value whatever or are even worse than valueless. Filters should be frequently cleansed in boiling water or in steam under pressure. Unless this is done, the filters may become incubators for bacteria.

[Ill.u.s.tration: FIG. 62.--PASTEUR WATER FILTERS.]

273. Distillation.--When an unquestionably pure water supply is desired, distillation should be resorted to. There are many forms of stills for domestic use which are easily manipulated and produce distilled water economically.[93] The mineral matter of water is in no way essential for any functional purpose, and hence its removal through distillation is not detrimental.

[Ill.u.s.tration: FIG. 63.--WATER STILL.]

274. Chemical Purification.--Purification of water by the use of chemicals should not be attempted in the household or by inexperienced persons. When done under supervision of a chemist or bacteriologist, it may be of great value to a community. Turneaure and Russell,[94] in discussing the purification of water by addition of chemicals, state:

"There are a considerable number of chemical substances that may be added to water in order to purify it by carrying down the suspended matter as well as bacteria, by sedimentation. Such a process of purification is to be seen in the addition of alum, sulphate of iron, and calcium hydrate to water. Methods of this character are directly dependent upon the flocculating action of the chemical added, and the removal of the bacteria is accomplished by subsidence."

275. Ice.--The purity of the ice supply is also of much importance.

While freezing reduces the number of organisms and lessens their vitality, it does not make an impure water absolutely wholesome. The way, too, in which ice is often handled and stored subjects it to contamination, and foods which are placed in direct contact with it mechanically absorb the impurities which it contains. For cooling water, ice should be placed around rather than in it. Diseases have frequently been traced to impure ice. The only absolutely pure ice is that made from distilled water.

276. Mineral Waters.--When water is charged with carbonic acid gas under pressure, carbonated water results, and when minerals, as salts of sodium, pota.s.sium, or lithium, are added, artificial mineral waters are produced. Natural mineral waters are placed on the market to some extent, but most mineral waters are artificial products and they are sometimes prepared from water of low sanitary character. Mineral waters should not be used extensively except under medical direction, as many have p.r.o.nounced medicinal properties. Some of the const.i.tuents are bicarbonates of sodium, pota.s.sium, and lithium; sulphates of magnesium (Epsom salts) and calcium; and chloride of sodium. The sweetened mineral waters, as lemonade, orangeade, ginger ale, and beer, contain sugar and organic acids, as citric and tartaric, and are flavored with natural or artificial products. Most of them are prepared without either fruit or ginger. Natural mineral waters used under the direction of a physician are often beneficial in cases of chronic digestion disorders or other diseases.

277. Materials for Softening Water.--The materials most commonly used for softening water are sodium carbonate (was.h.i.+ng soda), borax, ammonia, ammonium carbonate, potash, and soda lye. Waters that are very hard with limestone should have a small amount of was.h.i.+ng soda added to them. Two ounces for a large tub of water is the most that should be used, and it should first be dissolved in a little water. If too much soda is used, it is injurious, as only a certain amount can be utilized for softening the water, and the excess simply injures the hands and fabric. When hard limewater is boiled and a very little soda lye added, a precipitate of carbonate of lime is formed, and then if the water is strained, it is greatly improved for was.h.i.+ng purposes. Borax is valuable for making some hard waters soft. It is not as strong in its action as is sodium carbonate. For the hardest water 1/4 pound of borax to a large tubful may be used; most waters, however, do not need so much. Ammonia is one of the most useful reagents for softening water. It is better than was.h.i.+ng soda and borax, because the ammonia is volatile and does not leave any residue to act on the clothes, thus causing injury. For bathing purposes, the water should be softened with ammonia, in preference to any other material. Ammonia should not be poured directly into hot water; it should be added to the water while cold, or to a small quant.i.ty of cold water, and then to the warm water, as this prevents the ammonia from vaporizing too readily. Ammonia produces the same effect as potash or soda lye, without leaving a residue in the garments washed. It is especially valuable in was.h.i.+ng woolen goods or materials liable to shrink. Waters which are hard with alum salts are greatly benefited by the addition of ammonia. A little in such a water will cause a precipitate to form, and when the water is strained it is in good condition for cleaning purposes. Ammonium carbonate is used to some extent as a softening and cleaning agent, and is valuable, as there is no injurious effect upon clothing, because it readily volatilizes.

Caustic potash and caustic soda are sometimes employed for softening water, but they are very active and are not adapted to was.h.i.+ng colored or delicate fabrics. They may be used for very heavy and coa.r.s.e articles that are greasy,--not more than a gram in a gallon of water. Bleaching powder is not generally a safe material for cleansing purposes, as it weakens the texture of clothing. After a contagious disease, articles may be soaked in water containing a little bleaching powder and a few drops of carbolic acid, followed by thorough rinsing and bleaching in the sun. But as a rule formaline is preferable for disinfecting clothing. It can be used at the rate of about one pound to 100 gallons of water. Bleaching powder, caustic potash or soda, and strong soap are not suitable for cleaning woodwork, because of the action of the alkali on paint and wood; they roughen the surface and discolor the paint.

Waters vary so in composition, that a material suitable for softening one may not prove to be the best for softening another. The special kind must be determined largely by trial, and it should be the aim to use as little as possible. When carbolic acid, formaline, bleaching powder, and caustic soda are used, the hands should be protected and the clothes should be well rinsed.

[Ill.u.s.tration: FIG. 64.--TYPHOID BACILLI.]

278. Economic Value of a Pure Water Supply.--From a financial point of view, the money spent in securing pure water is one of the best investments a community can make. Statisticians estimate the death of an adult results in a loss to the state of from $1000 to $5000; and to the losses sustained by death must be added those incurred by sickness and by lessened quality and quant.i.ty of work through impaired vitality,--all caused by using poor drinking water. Wherever plants have been installed for improving the sanitary condition of the water supply, the death rate has been lowered and the returns to the community have been far greater than the cost of the plant. Impure water is the most expensive food that can be consumed.

CHAPTER XX

FOOD AS AFFECTED BY HOUSEHOLD SANITATION AND STORAGE

279. Injurious Compounds in Foods.--An ordinary chemical a.n.a.lysis of a food determines only the nutrients, as protein, carbohydrates, and fats; and unless there is reason to believe the food contains injurious substances no special tests for these are made. There are a number of poisonous compounds that foods may contain, and many of them can but imperfectly be determined by chemical a.n.a.lysis. Numerous organic compounds are produced in foods as the result of the workings of microorganisms; some of these are poisonous, while others impart only special characteristics, as taste and odor. The poisonous bacteria finding their way into food produce organic compounds of a toxic character; and hence it is that the sanitary condition of a food, as influenced by preparation and storage, is often of more vital importance than the nutrient content.[95]

[Ill.u.s.tration: FIG. 65.--TUBERCULOSIS BACILLI. (After CONN.)

Often present in dust particles and contaminated foods.]

280. Sources of Contamination of Food.--As a rule, too little attention is given to the sanitary handling and preparation of foods.

They are often exposed to impure air and to the dust and filth from unclean streets and surroundings, and as a result they become inoculated with bacteria, which are often the disease-producing kind. Gelatine plates exposed by bacteriologists under the same conditions as foods develop large numbers of injurious microorganisms. In order to avoid contamination in the handling of food, there must be: (1) protection from impure air and dust; (2) storage in clean, sanitary, and ventilated storerooms and warehouses; (3) storage of perishable foods at a low temperature so as to r.e.t.a.r.d fermentation changes; and (4) workmen free from contagious diseases in all occupations pertaining to the preparation of foods. Ordinarily, foods should not be stored in the paper wrappers in which they are purchased, as unclean paper is often a source of contamination.

281. Sanitary Inspection of Food.--During recent years some state and city boards of health have introduced sanitary inspection of foods, with a view of preventing contamination during manufacture and transportation, and this has done much to improve the quality and wholesomeness. Putrid meats, fish, and vegetables are not allowed to be sold, and foods are required to be handled and stored in a sanitary way.

Next to a pure water supply, there is no factor that so greatly influences for good the health of a community as the sanitary condition of the food. While the cooking of foods destroys many organisms, it often fails to render innocuous the poisons which they produce, and furthermore the unsound foods when cooked are not entirely wholesome, and they have poor keeping qualities.

Often meats, vegetables, and other foods eaten uncooked, as well as the numerous cooked foods, are exposed in dirty market places, and acc.u.mulate large amounts of filth, and are inoculated with disease germs by flies. Protection of food from flies is a matter of vital importance, as they are carriers of many diseases. In the case of typhoid fever, next to impure drinking water flies are credited with being the greatest distributors of the disease germs.[96]

[Ill.u.s.tration: FIG. 66.--DIPHTHERIA BACILLI. (After CONN.)

Often present in dust particles and in food unprotected from dust.]

282. Infection from Impure Air.--The dust particles of the air contain decayed animal and vegetable matter in which bacteria are present; these find their way into the food when it is not carefully protected, into the water supply, and also into the lungs and other organs of the body.

When foods are protected from the mechanical impurities which gain access through the air, and fermentation is delayed by storage at a low temperature, digestion disorders are greatly lessened. From a sanitary point of view, the air of food storerooms and of living rooms should be of equally high purity. When foods are kept in unventilated living rooms, they become contaminated with the impurities thrown off from the lungs in respiration, which include not only carbon dioxid, but the more objectionable toxic organic materials.

Vegetable foods need to be stored in well-ventilated places, as the plant cells are still alive and carrying on life functions, as the giving off of carbon dioxid, which is akin to animal respiration; in fact, it is plant-cell respiration. Provision should be made for the removal of the carbon dioxid and other products, as they contaminate the air. When vegetable tissue ceases to produce carbon dioxid, death and decay set in, accompanied by fermentation changes.

283. Storage of Food in Cellars.--Cellars are often in a very unsanitary condition, damp, poorly lighted, unventilated, and the air filled with floating particles from decaying vegetables. The walls and shelves absorb the dust and germs from the foul air and are bacterially contaminated, and whenever a sound food is stored in such a cellar, it readily becomes inoculated with bacteria. There is a much closer relations.h.i.+p existing between the atmosphere of the cellar and that of the house than is generally realized. An unclean cellar means contaminated air throughout the house. When careful attention is given to the sanitary condition of the cellar, many of the more common diseases are greatly reduced. Cases of rheumatism have often been traced to a damp cellar. In some localities where the cellars are unusually unsanitary, there is in the season of spring rains, when they are especially damp and contain the maximum of decayed vegetation, a prevalence of what might be called "cellaritis." The symptoms differ and the trouble is variously attributed, but the real cause is the same, although overlooked, for, unfortunately, doctors do not visit the cellar.

Cellars should be frequently cleaned and disinfected, using for the purpose some of the well-known disinfectants, as formaline, bleaching powder, or a dilute solution of carbolic acid. It has been found in large cities, when the spread of such diseases as yellow fever was imminent, that a general and thorough cleaning up of streets and cellars with the improved sanitary conditions resulting greatly lowered the usual death rate.

[Ill.u.s.tration: Fig. 67.--DUNG FUNGUS. (After b.u.t.tERS.)