Underground miners are exposed to a number of agents, in addition to radon progeny which may adversely affect the lung. Several of these agents are known or suspect carcinogens (arsenic, diesel exhaust, and silica), and some may cause airways inflammation (blasting fumes and diesel exhaust). Silica exposure causes silicosis and several investigations have assessed modification of the effect of radon progeny by the presence of this fibrotic disorder.
These exposures of miners, in addition to radon progeny, are a source of uncertainty in extending risk estimates based on the epidemiologic studies of miners to the general population. Inflammatory changes in the epithelium might non-specifically affect the risk of lung-cancer from radon progeny and the additional exposure to other carcinogens might alter the risk of radon progeny as well. These other exposures were considered in the BEIR IV report (NRC 1988) and subsequently in the radon dose panel report (NRC 1991).
In this appendix, we update the earlier reviews for exposure to arsenic, silica, and diesel exhaust. Information on exposures of the miners to the agents is limited and only a few studies provide human information on arsenic and silica. None of the studies have direct information on exposure to diesel exhaust. The limited data available on these exposures are summarized by cohort in appendix D. Use of diesel engines in U.S. mines is described in the workshop summary that is part of appendix E annex 2. The more general topic of interactions between agents is addressed in appendix C in considering the combined effect of cigarette smoking and radon.