A SURVEY OF THE CZECHOSLOVAK FOLLOW-UP OF LUNG-CANCER MORTALITY IN URANIUM MINERS

The major Czechoslovak cohort of uranium miners (S-cohort) is surveyed in terms of diagrams illustrating dependences on calendar year, age, and exposure to radon and radon progeny. An analysis of the dose depen dence of lung cancer mortality is performed by nonparametric and, subs equently, by parametric methods. In the first step, two-dimensional is otonic regression is employed to derive the lung cancer mortality rate and the relative excess risk as functions of age attained and of lagg ed cumulated exposure. In a second step, analytical fits in terms of r elative risk models are derived. The treatment is largely analogous to the methods applied by the BEIR IV Committee to other major cohorts o f uranium miners. There is a marked dependence of the excess risk on a ge attained and on time since exposure. A specific characteristic of t he Czechoslovak data is the nonlinearity of the dependence of the lung cancer excess risk on the cumulated exposure; exposures on the order of 100 working level months or less appear to be more effective per wo rking level month than larger exposures but, in the absence of an inte rnal control group, this cannot be excluded to be due to confounders s uch as smoking or environmental exposures. A further notable observati on is the association of larger excess risks with longer protraction o f the exposures.