Certain features of the Public health are most prominent from the social standpoint. The development of industrial life has brought many problems of most pertinent concern. Among them are industrial diseases, such as arsenic, lead and phosphorus poisoning, child labor, hours of labor, the employment of women in certain industries, sanitation of working quarters, and the responsibility of employers for the life and activities of employees outside of the workroom. The rapid growth of facilities for travel and the enormous number of travelers on railroads and steamships presents some unexpected problems in the sanitation of common carriers. Several instances are recorded of smallpox spreading in Pullman coaches. Mosquitoes, fleas, bedbugs and flies may easily carry an infection over long distances by aid of the railroad. A typhoid carrier can infect every water supply traversed by his train between Los Angeles and New York. The prevention of accidents in mines, and other industries, improved methods of controlling epidemics, and preventable diseases, and of saving the victims of common accidents like drowning, prevention of overcrowding in cities, proper housing of the poor; these are but a few of the numberless problems in the new science of public hygiene, from the standpoint of social public health.
The physical public health is concerned with communicable disease and its direct results, as in epidemics, while mental public health considers the prevalence, prevention and care of mental disorders, and the new science of mental hygiene.
One of the most important of the factors having to do with the public health is immigration. Not in the world's history has so vast an ethnic movement been recorded as that from Europe to America. The tribal migrations of ancient Europe are puny indeed compared to the great tide of a million and a quarter souls coming every year to the
