SANITARY SCIENCE, the science which deals with the preservation of health and the prevention of disease. Considered broadly, disease is due to environmental conditions which cause in jury of the living body. The causes of disease are usually divided into the ex. ternal, which act from without, and the internal, due to imperfection of the body, but these imperfections in the first instance are due to external causes. Sanitary science then comes to be the study of the influence of unfavorable environmental conditions on the body during the entire course of life from conception to death. Public health, which deals with disease causes, of such a character as to produce an effect on the general population, personal hygiene or the preservation of the health of the individual, infectious diseases and the measures of protection against them, the influence of age, climate and occupation on health, water supplies, the nutritive values of foods and the methods of marketing and preserving foods, meth ods of the disposal of waste material, the construction of dwellings and fac tories and the influence of factory life on the workers, vital statistics by means of which the state of health of a com munity can be ascertained, social pa thology or the influence of poverty and social conditions in the production of disease; all these and many more are considered under sanitary science, and for the most part form separate de partments of it.
Health of its people is considered the most important asset of a state, and nothing contributes more to happiness and well being. Sickness renders the state not only less efficient in produc tion and less capable of defense, but the care of the sick and indigent, for poverty and sickness go together, is an enormous tax upon the well. Good health is not even a matter of indi vidual choice, but for the sake of the well-being of society the individual is restrained from actions which would be injurious to himself or to others. A great mass of laws, national, state and local, designed for the protection of tin; people against disease, have been en acted and large sums of money from the public funds appropriated to fur ther health measures. All conditions affecting health have increasingly be come the subject of intense study and a large amount of knowledge based upon experience and experiment is now avail able. As in all matters which involve consideration of living things there is still much which is uncertain, and with the scientific knowledge there is inter mingled much supposed knowledge based merely upon tradition and insufficient experience. Great changes are taking place, such as the increasing industrial ism bringing with it the depletion of the rural population and the increase of the urban, the greater facility of transpor tation increasing the range of the en vironment, and the full effect of such changes upon the general health cannot yet be fully ascertained. There is still
lacking such information of the condi tions in the past as to afford a proper basis for comparison with the present. We do not accurately know whether or no the general health of the people has been affected by the influence of mod ern conditions. From such statistics as have been gleaned from the medical examination of large numbers of drafted men in the late war, the figures show a large percentage of individuals who have become defective through disease. These statistics represent the general health of the males of military age in the state. In Great Britain the medical examinations have shown that of every nine men there were three perfectly fit and healthy; two were upon a definitely infirm plane of health and strength, whether from some disability or failure of development; three men were incapa ble of undergoing more than a very moderate degree of physical exertion, and could in justice to their age be de scribed as physical wrecks, and the re maining man was a chronic invalid with a precarious hold upon life. This ex amination brought out also the effect of occupation upon health, the agricultural population having the best showing, with a decided fall in the industrial occupations, culminating in the tailors and barbers. The examination of the drafted men in the United States showed that in the total male population of mili tary age there were four hundred and sixty-five defective individuals of every thousand examined. Although these ex aminations were of males only, there is no reason to think that the females would have made a better showing, for the causes act upon all alike. Certain districts in London, where overcrowded and bad hygienic conditions notoriously exist, showed an enormously higher per centage particularly of respiratory dis eases, affording a striking illustration of the baneful influence of bad environ mental conditions in relation to these particular diseases, and in almost every other disease these black list districts showed a higher percentage than did the normal areas. The numerical regis tration and tabulation of population, mar riages, births, diseases and deaths, with analysis of the resulting phenomena is not of recent origin, but the develop ment of their present form and the ac curacy attained is comparatively mod ern. There is difficulty always in the carrying out of laws, the necessity for which is not perfectly understood. They are not efficient without the co-operation of the people, and this co-operation can be attained only through education. For this purpose the instruction of school children in the elementary principles underlying health preservation, and in culcating in them good habits of life is of the utmost importance. The care of these children during school attend ance is assumed by the state, and their education in measures of health control is not less important than the other branches of study.