Hazards of the Job traces the development of the field of occupational health from a "highly diverse, localized, and contradictory" body of knowledge to a more modern science based on quantitative, experimental techniques. In late-19th-century America, occupational diseases such as lead poisoning and silicosis were on the rise but went unrecognized. Physicians were stymied by nonspecific clinical presentations, the lack of scientific data, an orientation toward individual patients rather than groups, and their own loyalties to factory owners. Workers tended to ignore symptoms, avoid doctors, and resist attributing their illnesses to their occupations, which could lead to job loss. Legal traditions favored employers and usually precluded linking workplace exposures to illnesses.