This testimony concerned the efforts of NIOSH in the area of cancer and respiratory disease. The number of recognized occupational carcinogenetic substances was long and continued to grow. The effort to identify these hazardous elements in the work place was complex as many of the agents work in concert with others, clouding the picture of cause and effect. Individual lifestyles also played a part. The long latency period of cancer in the human body has prevented us also from knowing now the real prevalence of work related cases of the disease. Very high levels of production of many of these toxic chemicals have only occurred since the 1960s. While there has been a large amount of attention focused on occupationally related cancer, this should not obscure the fact that workers are also at risk of contracting a wide variety of nonmalignant occupational diseases and disorders such as respiratory disease. Inhalation was by far the most important route by which industrial substances could enter the worker's body. Such inhalation could result in irritation, inflammation, allergic reactions, edema, emphysema, fibrosis, or cancer. The most important nonmalignant occupational respiratory diseases included coal worker's pneumoconiosis, asbestosis, byssinosis, and silicosis. Offending agents include cotton dust, coal dust, asbestos (1332214) fibers, and silica (14808607) dust. Recent epidemiologic studies suggestive of a relationship between occupation and cancer were listed.