The committee concluded that the findings in the miners could be reasonably extended to the general population; there is no basis for considering that effects would be observed in the range of typical exposures of the general population that would not be observed in the underground miners exposed at generally much higher levels. The studies in the general population are ecologic and subject to many potential biases. The committee agrees with the conclusion of Darby and others that there is no need to consider cancers other than lung-cancer in setting protection standards and guidelines for radon. The dose calculations suggest that radon and progeny could contribute to some proportion of skin-cancer cases.
Only 2 new studies had been reported on nonmalignant respiratory diseases. The report from New Mexico again documented that uranium mining adversely affects lung function (Mapel and others 1996). Archer and colleagues (1996) described an intriguing series of cases that support the possibility that exposure to radon progeny cause fibrosis of the pulmonary interstitium, often referred to as pulmonary or interstitial fibrosis. However, this clinical case series is insufficient to establish the link to radon progeny specifically, and there is a need for more research on the persistent question of the existence of radon-related pulmonary fibrosis.
The new case-control study of reproductive outcomes in Shiprock, New Mexico, was limited by sample size and the possibility of measurement error because of the reliance on self-reported exposure measures. The committee was unable to reach any conclusion with regard to adverse effects of radon exposure on reproductive outcome.