Controversies in asbestos-related lung cancer.

Despite clear agreement that asbestos exposure causes lung cancer and despite prodigious research efforts in clinical, epidemiologic, toxicologic and mineralogic aspects of the problem, wide disagreement exists in the scientific community on many crucial points. Put in the simplest way neither the biologically relevant measure of dose nor the full shape of the dose-response curve at either the high or (especially) low end is understood. Nor is the relationship between the carcinogenic potential of the fibers and their fibrogenic properties. In the long run, full resolution of these issues will probably require the unravelling of the basic mechanisms by which the fibers induce cancer; unfortunately, despite recent progress, this understanding is probably too far off to be of use in the solution to the very real, omnipresent clinical and public health cancer-control problems. Decisions will have to be made using data sets far less satisfactory. Hopefully, by pursuing some of the avenues suggested in the sections above, enough can be learned to facilitate more rational approaches to the problems at hand.