Although most attacks of food poisoning are usually of a slight and apparently temporary nature, it does not follow that they are to be considered negligible or of trivial importance from the standpoint of public health. The human organism is always more or less weakened by such attacks, many of them, as we shall see, genuine infections; and, as is known to be the case with many infectious diseases, some permanent injurious impression may be left on the body of the affected individual. Under certain conditions it is possible that degenerative changes are initiated or accelerated in the kidneys or blood vessels by the acute poisoning which is manifested for a short time in even the milder cases. In yet greater degree these changes may follow those insidious forms of food poisoning due to the frequent ingestion of small quantities of mineral or organic poisons, which in each dose may cause little or no measurable physiological change, but whose cumulative effect may be vicious. In view of the grave situation evidenced by the increase in the degenerative diseases affecting early middle life in the United States,[1] the extent, causes, and means of prevention of food poisoning seem pressing subjects for investigation. THE EXTENT OF FOOD POISONING Since cases of food poisoning, "ptomain poisoning," and the like are not required by law to be reported, public health authorities in general possess no information respecting their occurrence. Very indirect and imperfect indications of the prevalence of certain kinds of food poisoning are afforded by casual press reports. Such as they are, these accounts are the only available material. Tables I and II summarize data I have gathered through a press-clipping bureau and other sources during the period October, 1913, to October, 1915. They serve to show at least the universality and complexity of the problem. The 375 group and family outbreaks together involved 5,238 persons. While it is not probable that all the instances reported as due to food poisoning can properly be so considered, there is no doubt that the number recorded in the tables falls far short of the actual occurrences. In the past few years the writer has investigated several large food-poisoning outbreaks which have never been reported in the press nor received public notice in any way. There is reason to think that the majority of cases escape notice. Probably several thousand outbreaks of food poisoning in families and larger groups, affecting at least 15,000-20,000 persons, occur in the United States in the course of a year. The assignment of causes indicated in Table I is of limited value. The tendency to incriminate canned food is here manifest. Proper investigation of the origin of an outbreak is so rarely carried out that the articles of food ordinarily accused are selected rather as the result of popular prejudice and tradition than of any careful inquiry. TABLE I