Document jmEZDX8Krw8J3OBR94ko9yKeZ

10 OCCUPATIONAL TUMORS AND ALLIED DISEASES age of forty years, any addition to existing information on the causation and causative mechanism of cancer is a highly important matter. This statement receives additional emphasis from the fact that in spite of definite advances made in the diagnosis and therapy of malignant diseases, and in spite of the increased cancer-consciousness of the general public, there has not been noted any appreciable reduction in the rate of cancer mortality (Wood). The farreaching practical significance of the study of industrial cancers is derived from the light which such investigations shed upon the importance of pre ventive measures in the fight against cancer and upon the causes and causative mechanism responsible for these growth manifestations. 2. DEFINITION AND CLASSIFICATION OF OCCUPATIONAL TUMORS The term "occupational tumor" is applied to blastomatous reactions orig inating in individuals during the course, and as the result of, the regular and usually prolonged exercise of certain occupational activities entailing contact with some exogenous, physical or chemical, carcinogenic agent acting in proper intensity. These occupational neoplasms proper are caused in general by specific factors which form an integral part of ordinary working conditions. They must be distinguished from accidental occupational tumors which result from or fol low upon some extraordinary, unforeseen, accidental injury sustained while at work. The blastogenic factors allegedly responsible for these accidental neoplasias are of nonspecific nature, and consist primarily and usually of a single or repeated physical or chemical trauma unrelated to regular occu pational influences. Occupational tumors thus represent a variety of thie environmental neo plasms, i.e., blastomatous responses to the action of certain specific extraneous cancerigenic factors of natural or artificial origin. The existence of nonoccupational environmental cancers provides not only additional proof of the importance of exogenous agents in the causation of malignant and benign growths, but represents also a material source of information for the study of. occupational blastomas. Non-occupational environmental tumors and related manifestations are, like the occupational variety, the result of extraneous in fluences of various kinds, such as habits (carcinoma of the oral cavity in betel nut chewers; carcinoma of the skin of the abdominal region in carriers of kangri [Kashmir] or kairo [Japan]); carcinoma of'the penis due to un cleanliness and the use of caustic therapeutics in Chinese; customs (keloids in colored races caused by decorative scarring); climatic factors (skin cancers among light pigmented inhabitants of dry and sunny regions [Australia, Argentina, Midwestern States]); geological influences (cancer of the skin among inhabitants of areas in which the water supply is contaminated by arsenic from arsenic-containing ores [Silesia, Argentina]); adenomas and carcinomas of the thyroid among inhabitants of regions in which endemic goiter occurs because of iodine deficiency of the soil (Switzerland, Great Lakes