XXV SOME SANITARY ASPECTS OF MILK SUPPLIES AND DAIRYING* BY SEVERENCE BURRAGE It has been gen This subject of public milk supplies is not a new one. erally known for some time that milk and butter may be, and often are adulterated, and the legislature, by the enactment of laws, have in several cases protected the citizens against this fraud. But a far more serious fact from the sanitary standpoint is this: that milk and butter are commonly polluted, containing filth and foreign materials which are more or less dangerous to the health. Infected milk has frequently carried the germs of disease and caused severe epidemics. This paper has been written for the purpose of attracting attention to this bacteriological side of the subject, to show its importance to community life, and by the diffusion of facts to make it possible to blot out in the near future some of the dangers that now exist. The following figures, taken from the eleventh United States census, will show the importance of the dairying industry in our State: Production of milk in Indiana for 1889, Production of cheese 200,510,797 gallons. 48,477,776 pounds. Figuring at eight cents a gallon for milk, ten cents a pound for butter, and five cents a pound for cheese, gives a total value of $20,906,687.76. These figures have undoubtedly increased considerably since 1889, and could the corresponding figures be obtained for 1895 they would give a much more striking illustration of the value of dairying to the commonwealth. It is certainly possible to raise the general standard of dairying throughout the State. Much trouble arises from the ignorance or carelessness of the milkmen. If they are uncleanly in their habits, if they do not take the proper care of their own bodies, and of the cattle and stable, they add an important factor toward making serious and dangerous conditions. The more unfavorable these conditions, just so much more is the chance that the milk will depart from the normal. NORMAL MILK Cow's milk is essentially an animal secretion, the direct product of certain glands, whose function it is to manufacture this liquid food for the calf while it is too young to partake of the more solid food. The milk is secreted *Permission to reprint has been kindly granted by Purdue University, Department of Sanitary Science, located at Lafayette, Indiana. Monograph No 2. These prices were suggested by Prof. C. S. Plumb, Director of the Purdue Agricul tural Experiment Station. by these mammary glands, the cells of which actually contribute a certain portion of their own substance that they have manufactured from the blood. Thus we find stored in the udder a liquid made up largely of real animal substance, a rich food material suitable for human use. The chemical composition of milk will not be touched upon, as the proportions of its various constituents have little to do with the problems at hand. Suffice it to say, that this white, innocent looking liquid which is such an excellent food for the human family, is likewise a most fertile soil for various minute plants, micro-organisms belonging to one of the lowest divisions of the vegetable kingdom, scientifically known as "Bacteria." It has been shown that milk in the udder of a perfectly healthy cow is absolutely free from bacteria or germs of any kind; in other words, it is sterile or germ-free. If the milk could be used when first drawn from the cow, as was done by people in a more primitive or patriarchal state, who domesticated many of the milk-giving animals, as the cow, goat, mare, and camel, this object, viz.: germ-free milk, would be partly attained. They did not have to store the milk for any length of time, nor did they have to transport it from one place to another, but in the modern civilized community real fresh milk is seldom obtained. It is delivered several hours after milking, and it often has to pass through several different handlings before it is placed upon the table for consumption. Therefore, it is not surprising that we rarely find normal milk in city households. COMMERCIAL MILK IS NOT NORMAL MILK It has been proven that normal milk in the healthy cow's udder is free from bacteria. City milk, on the other hand, shows an entirely different condition. It is swarming with bacteria. The average number of bacteria in fifty-seven samples of milk taken in Boston, in the spring of 1890, was 2,355,500 per cubic centimeter, a quantity equal to a small thimbleful. In some fifteen samples, taken in the suburbs of Boston, from the tables of well-to-do families, whose milkmen were exceptionally good, the average number of bacteria per cubic centimeter was 69,143. American cities appear to have better milk from a bacterial standpoint than European cities. In the latter, milk seldom contains less than 5,000,000 per cubic centimeter In the milk supply of Middletown, Connecticut, the number of bacteria was found to be comparatively low. In this case the milk is delivered to the consumer within a few hours of milking, as it does not have to be sent on an extended railroad journey, as ordinary city milk often does. The bacteria varied from 11,000 to 300,000 per cubic centimeter. An examination of milk made at the end of a milking under the usual conditions, viz.: wide pail, and a more or less shaking of the udder during the process, showed an average of 30,500. Other figures might be given, showing the number of bacteria in the milk supplies of cities and towns, foreign and American, all showing that commercial milk had departed from the normal condition. It contains myriads of vegetable organisms. The examples cited above are sufficient to give an idea of the large numbers and will serve better as a demonstration than a long table of figures. MAJORITY OF BACTERIA IN MILK ARE HARMLESS All bacteria are not disease germs. A very small proportion of them are dangerous or harmful in any way. In this way they may be compared to the larger and more familiar forms of the vegetable kingdom, which can be seen every day in the field, the forest, and the garden. Here are hundreds of trees, shrubs, and plants, nearly all perfectly harmless, but there are some ten or fifteen forms, including the poison ivy (Rhus toxicodendron) and the poison oak (Rhus venenata), both poisonous to the touch, and spotted cow-bane (Cicuta maculata), and wild carrot (Daucus Carota), poisonous to eat, and have to be avoided. Just so it is with these minute bacteria. There are countless species that are perfectly harmless, and many are exceedingly useful. At the same time several dangerous disease-producing forms exist, causing such diseases as diphtheria, Asiatic cholera, and typhoid fever, which are much more to be dreaded than the poisons of the more familiar plants mentioned above. The conditions, moreover, which favor the growth of the harmful forms are usually favorable for the more dreaded ones, also, just as in the case of the higher plants. Of the enormous number of bacteria found in milk, cited on previous pages, it is possible that none were pathogenic, or disease producers, and would not in any way harm the public health. The fact remains true that where these harmless or non-pathogenic bacteria thrive it is possible for the dangerous ones to thrive also. It is believed by some authorities that the large number of bacteria existing in milk may have an important relation to the high death-rate among children under five years of age, as will be discussed on another page. Many of the common phenomena, as putrefaction and fermentation, are due to some of these minute organisms. The souring of milk will occur only when the lactic acid bacteria are present. If milk could be kept absolutely free from any contamination-from contact with any germs-it could be preserved indefinitely. All canning and preserving of fruits and vegetables is based upon this principle. The materials are cooked thoroughly, the high temperature killing all the germs; the cans are then sealed while still hot, and the air, always laden with spores of bacteria and molds, does not have access to the preserves. Consequently, if properly sealed, they should last indefinitely. Any means by which the milk can be protected from these germ-spores in the air must necessarily lengthen the time that the milk will keep fresh; and any method, such as cooling immediately after milking, thus retarding the growth of the organism, would give a similar result. SOURCES OF BACTERIA IN MILK (a) In the Barn and Vicinity If the normal milk in the udder of the cow is sterile, the first opportunity for bacteria to reach it would be during the operation of milking. It must be borne in mind that the bacteria are omnipresent, being in the air and soil, and particularly where dampness, dust, and dirt exist. Ordinary dust is made up of many spores of bacteria and molds, and it is evident that the conditions existing in a barn where cows are kept must be most favorable for the production of such dust. All animal refuse contains bacteria, and there is of necessity much such filth about the barn or stable, and even about the cows themselves, unless they are unusually well-kept. In order to show how many opportunities are afforded the milk to become contaminated, it will be instructive to follow closely the operation called milking, the usual method of drawing the milk from the udder. If it is in the morning, the man starts from the house perhaps without having washed himself, takes the milk pail, which is supposed to be clean, opens the barn, seats himself on a stool near the cow to be milked, and holding the milk pail between his knees, he seizes the teats with more or less violence, and proceeds to fill the pail. With the shaking of the udder, the switching of the cow's tail, and the possible rubbing of the cow's sides by the hat or head of the milker, much disgusting material is often dropped into the pail; in fact, the following impurities have been found in unstrained fresh milk: Manure particles (numerous), fodder particles (which have not passed the alimentary canal of the animals), molds and other fungi, cow hair (numerous), particles of the skin, human hair, parts of insects, down from birds, small wooden pieces, shavings, and pieces of fir-leaves, woolen threads, linen threads, soil particles (rather frequent), and moss particles, fine threads (most likely cobwebs), etc. Admitting that many of these coarser materials are strained out before the milk is delivered to the consumer, nevertheless, the bacteria that were on them would remain in the milk, and finding a warm rich soil, would increase most rapidly. The example given above is supposed to be carried out under average circumstances, but if we imagine the milkman or farm hand to be untidy about the care of himself, the barn and the herd of cows, it is not difficult to imagine that a much worse state of affairs might exist, and a great deal more filth of the most disagreeble kind be found in the milk. It sometimes happens that a farmer is careful about the care of his barn, and just before milking he conscientiously takes the precaution to sweep the floor and stalls most carefully. He has obviously chosen the worst possible time to do this, for he has stirred up the dust and dirt so that it will settle into the pail, onto the cow and onto himself; consequently much of this dust stirred up by his sweeping is likely to reach the milk. Many men will moisten the hands with the milk, as this makes the operation easier for them. Unless their hands, and the cow's udder and teats are unusually clean this is an exceedingly unfortunate practice. These illustrations, although very familiar to many of us, indicate clearly that under the most favorable circumstances, with the best conditions of barn, of men and of surroundings, it is only too easy for the milk to become an unpleasantly dirty food. This operation of milking seldom if ever occupies less than five minutes, and in that time, with the activity and stir within the vicinity of the pail, there would naturally much of the ordinary dust settle. It will not be required to further emphasize the fact that the barn and stable are the principal sources of bacteria in milk. (b) On the Road to the Consumer Much milk, especially city milk, has to travel a considerable distance before reaching the consumer, the journey sometimes taking several hours. During this time it is subjected to various temperatures, seldom low enough to in any way retard the growth of the organisms. In many places where it is transported by railroad, particularly in cities of the Eastern United States, ice is so extensively used that the numbers of bacteria are comparatively low; but if the milk cans have to s and upon the depot platform in the sun, as often happens; if the milk has to be changed from one set of cans to another, the chances are enhanced that the number of bacteria will be greatly increased. The effect of this is clearly demonstrated in milk which has been cooled directly after milking, such milk keeping fresh many hours after that which has been hurried directly from milking to the consumer. It has been observed that afternoon milk keeps much longer than morning's milk, which may be explained in this way, there being much more hurry and carelessness in the early morning. It not infrequently happens that certain circumstances arise, after the milk leaves the barn or the place of milking, which allow water to be added to the milk. Whether this be premeditated or not is out of the province of this paper to discuss, as it has been the purpose here to emphasize the contamination and pollution and not the adulteration of milk. It is an interesting fact, however, that milk to which water has been added contains, as a rule, less bacteria than ordinary milk. The reason for this is apparent. The food is a more dilute one and the bacteria will not multiply as rapidly in it, and the addition of water presumably containing not as many bacteria will lessen the number ordinarily found in the straight milk. But there is a danger right here that must be carefully guarded against. This water, although containing comparatively few bacteria, may have come from a contaminated well; it may contain the germs of disease, particularly typhoid fever, as will be seen on a subsequent page. These facts illustrate that the journey of the milk from the barn to the consumer is often a productive source of bacteria, and sometimes of dangerous ones. (c) In the Dwelling of the Consumer The house of the consumer, as a source of bacteria in milk, depends largely upon the habits of the family and servants with special reference to cleanliness. Milk pans and cans are difficult things to clean thoroughly. If the housewife or servant is at all careless some of the milk will remain lodged in the angles, and bacteria falling upon this, encouraged by the warm temperature of the kitchen, will flourish, awaiting the addition of fresh milk. The consumer's family should set a good example to the milkman by always returning to him the can or cans perfectly clean. (d) Diseased Cows, Farm Hands, and Milkmen In all previous illustrations it has been taken for granted that the cows have been healthy ones; that the farmer and his help have not been diseased in any way, and that the men afterwards handling or delivering the milk have been in perfect health. In the case of the cows, statistics seem to indicate that there is a far larger proportion diseased than has been generally supposed. Many cows suffering from tuberculosis appear even to the veterinarian to be in good health, thus making it difficult to separate the diseased cows from the healthy ones. Today, however, this has been partially remedied by the introduction of the tuberculin test, which seems to indicate without fail the animals suffering from this disease. It has been demonstrated conclusively that the bacillus tuberculosis, the germ of the disease, has been found in the milk of the diseased cow, particularly if the udder is affected. It may happen that these germs get into the milk from the dust of the barn as often as they do directly from the animal itself. But the fact remains that the milk of tuberculosis cows is apt to contain the germs of the disease. In regard to the persons that handle the milk after it leaves the cow, if they have suffered, or are suffering, from some sickness or disease, it is more than likely that some excretions or secretions from their bodies will reach the milk, unless they are exceedingly careful about their own personal cleanli |
