Rate of malignant tumor mortality among coal burning power plant workers occupationally exposed to arsenic.

The mortality pattern was retrospectively analyzed among the workers of a power plant A (exposure group) combusting coal with high arsenic levels and among the workers of power plants B, C and D (control group), where arsenic concentrations in coal were by one order of magnitude lower. The exposed group consisted of 88 and the control group of 159 male subjects deceased over the period of the last 15--18 years. The rate of tumor mortality among the exposed subjects who died during their productive age was 38% (in the control group 23%), among those died after 60 it was 51% (in the controls 43%). This increase in the tumor mortality rates was not statistically significant. What was, however, statistically proved to be significant is the fact that malignancy-caused deaths in the exposed group occurred in younger age categories and after a statistically shorter exposure time (in both cases p < 0.05). Combusted coal is known to contain a variety of biologically active microelements, but the amount of arsenic alone (950--1500 g/1 tonne of coal) most probably fully justifies the suspected link between the tumor incidence and the overexposure to arsenic.