Lung cancer risk associated with exposure to man-made fibers.

We show that available experimental data from long-term experiments are consistent with the hypothesis that the oncogenic potential of man-made fibers is determined completely by their biopersistence. We present an analysis of these data within the initiation-promotion-progression paradigm of carcinogenesis. Our method of analysis takes explicit account of the temporal pattern of fiber burden in the rat lung, and suggests that fibers act as initiators in the lung. We estimate a dose-dependent initiation parameter and show how it can be transported to human populations for assessment of the risk of lung cancer following exposure to man-made fibers.