Methods: We have notified and invited approximately 5,000 former NTS workers to a medical screening session. Workers complete an occupational and medical questionnaire, participate in a screening examination, and have biomedical tests performed including spirometry, chest x-ray, and audiometry. Individuals with specific exposures and/or screening abnormalities are invited back for routine follow-up screening.

Results: Of our 1100 participants to date, 88% report exposure to silica containing rock dust, 66% report exposure to asbestos, and 35% report accidental exposure to radiation. The participants are 60 years old and worked at the NTS for approximately 18 years, 30% never smoked, and 18% currently smoke. 24% have an FEV-1 less than 80% predicted and 15% have an FVC less than 80% predicted. Approximately 15% have B read chest x-rays of 1/0 or greater. The data will be considered in light of the cohort's known lung cancer risk factors.

Conclusions: Underground nuclear weapons workers were exposed to numerous respiratory fibrogenic and carcinogenic agents. Their risk for pneumoconiosis and lung cancer suggests that current occupational standards for these agents may be inadequate.