Long man-made fibers and lung cancer risk

We show that available experimental data from long-term oncogenicity experiments in Fisher rats are consistent with the hypothesis that the oncogenic potential of long man-made mineral fibers is determined mainly by their biopersistence. We present analyses of these data within the initiation-promotion-progression paradigm of carcinogenesis. Our method of analysis can take the temporal pattern of the burden of long fibers in the lungs of individual animals into explicit account. For this analysis, the temporal pattern of lung burden for each animal was imputed from the information obtained from sacrificed animals. The data are consistent with the hypothesis that fibers act as initiators in the rat lung. We present an estimate of the dose-dependent initiation parameter that is based on all the available data.