EXPERIMENTAL ASSESSMENT OF THE SHORT AND LONG-TERM EFFECTS OF RN-222 FROM DOMESTIC SHOWER WATER ON THE DOSE BURDEN INCURRED IN NORMALLY OCCUPIED HOMES

Previous studies of the effects of Rn-222 in drinking water have cente red on the long-term or chronic exposure to Rn-222 and its decay produ cts. In this study, the possible effects that the transient increase c aused by the release of Rn-222 from, shower water can have on the Rn-2 22 concentration have been studied. In addition, the increment in the lung dose incurred by the occupants of a normally occupied home and th e long-term increase in the Rn-222 concentration and the associated do se in the home has also been examined. Various parameters are of inter est including the release of the Rn-222 from the shower water, the rol e of ventilation as a removal mechanism, and the behavior of the aeros ol present in the home. Experimental work was performed in a shower st all constructed in the laboratory and in a bathroom in a normally occu pied home. The home was supplied with water containing around 550 kBq m(-3) of Rn-222. A transfer coefficient around 0.70 and equilibrium fa ctors up to 0.69 were measured in the laboratory. The ventilation rate s measured in the home were in agreement with those found in the liter ature, 0.5-4.0 h(-1). The dose incurred was assessed using the lung do se model developed by the International Commission an Radiological Pro tection (ICRP). Calculations indicated that for homes with Rn-222 in t he domestic water similar to the experimental home, the short-term exp osure during showering could contribute a 17% increase in dose over th e average daily dose. However, the increase in the long-term average c oncentration caused by the release of Rn-222 from water use in the hom e could more than double the average daily dose. Thus, the focus of co ncern regarding radon in domestic water should be primarily on its eff ects on the long-term airborne Rn-222 concentration.