X-ray evidence of increased asbestos exposure in the US population from NHANES I and NHANES II, 1973-1978. National Health Examination Survey.

OBJECTIVES

Jobs involving heavy asbestos exposure increase risk for lung cancer and mesothelioma substantially, and low-level exposures may carry some risk. At least one indicator of asbestos exposure, mesothelioma, has been increasing in the US for decades. We investigated the prevalence of another indicator, pleural thickening on x-ray, in a defined sample of the US population.

METHODS

Certified physicians read 1060 x-rays from the second National Health and Nutrition Examination Survey (1976-1980) for pleural changes consistent with pneumoconiosis, which are a reasonably specific indicator of asbestos exposure.

RESULTS

Prevalence estimates, in NHANES II, in the age group 35-74 years, are 6.4% (+/- 0.9%) among males, 1.7% (+/- 0.6%) among females, and 3.9% (+/- 0.6%) overall. These prevalences are approximately twice those estimated from NHANES I data (1971-1975).

CONCLUSIONS

X-ray evidence of asbestos exposure was common in the late 1970s and increasing. The increase may be due to occupational asbestos exposure, but it is so large as to suggest some contribution from environmental, non-occupational asbestos exposure.