Lung dose estimates from 222Rn in Arizona groundwater based on liquid scintillation measurements

Since August 1989, 222Rn groundwater samples from across the state of Arizona have been collected and analyzed using liquid scintillation. Of the 253 specimens acquired, 65% have 222Rn concentrations above 11 Bq L-1 (300 pCi L-1), while 16% have 222Rn activities over 37 Bq L-1 (1,000 pCi L-1). The geometric mean 222Rn concentration for all the wells tested is 13 Bq L-1 x divided by 4; the arithmetic mean is 37 +/- 122 Bq L-1. Using the geometric mean, it is estimated that an additional tracheobronchial lung dose equivalent of 0.19 mSv y-1 x divided by 13.9 is delivered to Arizona residents from the well water to home pathway.