CHAPTER VI WATER AND ITS RELATION TO DISEASE Water is a vehicle for certain infections such as cholera, typhoid fever, dysentery, and other diseases, having their primary seat in the digestive tract. It may carry inorganic poisons such as lead. It is responsible for a large group of nutritional and dietetic disorders less well understood. It may contain qualities which bring about derangements of metabolism resulting in such conditions as goiter; further, it may be the medium for carrying infections now not generally regarded as water-borne, or it may lower resistance so as to favor infections not water-borne. It is also occasionally responsible for conveying animal parasites, amebæ, worms, etc. While water has an established place among the carriers of certain infections, it has not a supreme or exclusive place, and this should be kept carefully before us. The tendency to exaggerate the importance of water as a bearer of disease and death has sometimes led to overstatement. The facts are bad enough and do not require extravagant language to emphasize their importance. The greatest danger in water is pollution from human sources. All the discharges from the body: urine, feces, expectoration, secretions from the nose, and washings from the skin, find their way sooner or later into our streams, especially where modern water-carriage systems are installed for the disposal of wastes. All sewage-polluted water must be regarded as dangerous, whether there are any known cases of typhoid fever on the watershed or not. It is highly probable that the sewage of large communities always contains typhoid bacilli in larger or smaller numbers, because in large communities typhoid fever does not die out completely at any time, and carriers and missed cases are growing in interest and importance. Water differs in several essential particulars from any other article of diet. Above all, it is partaken of raw, while perhaps 90 per cent. of all our other food is disinfected by cooking before it is used. Again, it is a vehicle which comes in contact with many objects spread over broad acres, and it is the natural vehicle for the removal of wastes from these Its great solvent and erosive powers favor this action. areas. The relation of water supply to sickness and death has been shown with force in many cities, notably at Lowell and Lawrence, Mass.; in Albany, N. Y.; at Jersey City and Newark, N. J.; at Philadelphia and Pittsburgh, Pa.; at Chicago, Ill.; and abroad at London, Paris, Hamburg, Altona, Berlin, and many other cities. THE MILLS-REINCKE PHENOMENON Following the filtration of the water supply of Lawrence, Mass., in September, 1893, Mr. Hiram F. Mills, a member of the State Board of Health of Massachusetts, noted that a marked decrease in the general death rate of the city, and not merely in the death rate from typhoid fever, was taking place. About the same time (May, 1893) filtered Elbe River water was furnished the city of Hamburg, and Dr. J. J. Reincke, health officer of that city, in his successive annual reports, noticed that the general death rate was declining more rapidly than could possibly be accounted for by the deaths from typhoid fever alone. To this important discovery Sedgwick and MacNutt have given the name of the "Mills-Reincke phenomenon." In 1904 Mr. Allen Hazen, a sanitary engineer, formulated a numerical expression for the comparative effect of water purification upon typhoid fever mortality and total mortality. He said that, "where one death from typhoid fever has been avoided by the use of a better water, a certain number of deaths, probably two or three, from other causes have been avoided." The Mills-Reincke phenomenon and Hazen's theorem have been searchingly studied by Sedgwick and MacNutt, and the student is advised to read the original article referred to in the footnote. These authorities examined the vital statistics of the cities of Lawrence, Mass., and Hamburg, Germany, and also of Lowell, Mass., Albany, Binghamton, and Watertown, N. Y. They found abundant evidence of the great life-saving power of a purified water in preventing many diseases other than typhoid fever in the cities studied, except Watertown, and in this case it is possible that the purification of the public water supply has been as yet relatively imperfect.. It is further to be noted that the method of purification used at Watertown is mechanical filtration. Sedgwick and MacNutt express the opinion that Mr. Hazen's theorem applied to the cities they studied, with the exception of Watertown, appears to be sound and conservative. In Hamburg the saving in typhoid mortality was slight in comparison with the saving of mortality in other diseases combined; that is, roughly, only about 1 W. T. Sedgwick and J. S. MacNutt: "The Mills-Reincke Phenomenon and Hazen's Theorem Concerning the Decrease of Mortality from Diseases Other Than Typhoid Fever Following the Purification of Public Water Supplies," Jour. Infect. Dis., Vol. VII, No. 4, Aug. 24, 1910, pp. 489-564. 1 to 16. In the other cities the ratios differed widely from this. Thus, at Lawrence it was 1 to 4.4, at Lowell 1 to 6.0, in Albany about 1 to 4.1, and in Binghamton only about 1 to 1.5. It is clear, therefore, that Hazen's theorem is merely a convenient formula rather than a precise methematical expression. One of the most surprising results of these studies is the disclosure of the remarkable relation subsisting between polluted water and infant mortality. This was emphasized especially by Dr. Reincke at Hamburg. Closely associated with infant mortality stand diarrhea and gastrointestinal disorders in relation to polluted water, which now bids fair to assume a causal importance in these diseases second only to that of contaminated milk. In regard to tuberculosis the evidence, though less striking, is interesting and suggestive. Sedgwick and MacNutt state that, "inasmuch as they have been unable even after the most careful investigation to discover any other possible explanation of the figures, they are forced to the conclusion that a considerable portion of the decline in mortality from tuberculosis in Lawrence and Lowell during the years immediately following a change from a polluted water supply was due to that change, and in line with this conclusion a similar explanation appears more than probable for Hamburg. A somewhat similar relation stands for pneumonia, bronchitis, and the acute respiratory diseases." The question naturally arises as to what such decline of mortality observed in the Mills-Reincke phenomenon for diseases other than typhoid fever is due. The natural suggestion is that it either results from an increased vital resistance resulting from the use of purer water or an exclusion of the disease germs, or perhaps the phenomenon might be due to a combination and coöperation of these two factors. 2 McLaughlin has also stated the relation of a sewage-polluted water to infant mortality, and concludes that it is certain that in practically every instance, in addition to a lessened number of deaths from typhoid fever, the substitution of a safe for a polluted water supply results in the saving of many lives from diseases which are not reported as typhoid fever. Hazen's theorem has also been studied by Arthur Lederer, who finds a large number of affirmative statistical results from which, together with our direct and indirect proof of the prevalence of waterborne diseases, it seems safe to assume that the influence of an improved water supply upon the death rate in general is correct. The theorem seems well borne out by the figures in the following table: 'Pub. Health Reports, Vol. XXVII, No. 17, Apr. 26, 1912. Impure water is responsible for disorders other than the specific gastrointestinal infections, but these disorders are often obscure or overlooked. It is not always plain just what quality or what impurity in the water is responsible for these non-specific disorders, and the diseases themselves may present a vague and ill-defined clinical picture. The relationship has been worked out in only a few instances. A turbid or malodorous water may not in itself be particularly injurious to health, but, on account of its unattractive appearance or repulsive condition, less may be taken than is necessary for the maintenance of good health. In this way water may be indirectly responsible for much harm. The drinking of too little water is a very common dietetic error. While a polluted water may not carry specific germs, it may so undermine health or lower resistance as to favor infections not usually associated with the digestive tract, such as pneumonia and tuberculosis and the diseases responsible for infant mortality. From the nature of the case the effects of an impure water cannot always be measured by gross results, but the cumulative or separate action of small effects often repeated may result in deranged digestion, altered metabolism, irritation of delicate membranes or sensitive organs and structures, which may lead to or hasten the course of chronic diseases. The organic matter in the quantities usually contained in a natural water is not of itself harmful. This organic matter, however, does not stay in its native state, but soon putrefies, and it is suspected that some of the intermediate products of putrefaction may have toxic potency. Ordinarily these toxic substances are in minute quantities, or at least in great dilution, but under certain circumstances they may accumulate in noticeable concentration. Further, while persons habitually taking such toxic substances may soon become immune, the new-comer will not be so fortunate. The case of organic matter in water is not a clear one, and sanitarians have ever erred on the safe side in condemning waters containing much organic matter. It is well known that if the organic matter is not derived from sewage it is probably harmless. Thus, in the case of organic matter of vegetable origin, Mason has been able to find but few cases of illness traceable to peaty waters. In such instances the patients suffered from a mild and transient form of diarrhea. I am familiar with an outbreak of diarrhea traced to a dead fish caught in the water meter of a hospital. This is probably a type of water-borne disease due to organic pollution which is not infrequent. Whether in such cases the trouble is due to bacteria or to bacterial toxins, or to the degradation products of protein decomposition, cannot always be made out. As far as the inorganic impurities usually found in water are concerned, the chlorids, carbonates, sulphates, and silicates, and lime, magnesia, and aluminium can scarcely be harmful in the amounts ordinarily found. It is commonly stated that water containing 500 parts per million, or 30 grains per gallon, of clay and silt is unfit for drinking purposes, on account of its irritating effects upon the gastrointestinal tract; but beyond this probability, turbidity is of no special sanitary significance, unless the water also contains metallic poisons or objectionable chemicals. An attempt has frequently been made to correlate the formation of concretions such as urinary and biliary calculi with the inorganic salts in water. We now know that biliary calculi usually form about a colon bacillus or a typhoid bacillus or about some pathological particle as a nucleus, and that urinary calculi probably have a similar pathogenesis. There is no known relation between these concretions in the body and the inorganic salts in water, even those in a very hard water. The relation of inorganic substances in water to goiter will be discussed separately. Goiter.-Goiter or struma is a chronic enlargement of the thyroid gland. It occurs as epidemics, is endemic in places, and sporadic cases may arise anywhere. Goiter has many of the earmarks of an infectious disease, although it is not communicable from person to person, the cause being derived from his environment. The epidemics are usually of short duration, limited extent, and commonly occur in goiter regions. The classic home of endemic goiter is in the Swiss Alps. In certain regions of these mountains it is very prevalent. Thus, in Piedmont it sometimes affects more than two out of every three of the inhabitants. It also occurs in the mountains of Austria, France, and |