RADIUM-BEARING PIPE SCALE DEPOSITS - IMPLICATIONS FOR NATIONAL WATERBORNE RADON SAMPLING METHODS

A point-of-use waterborne radon-222 (Rn-222) survey of a small Iowa to wn was performed to determine the cause of unnaturally high waterborne Rn-222 concentrations in the municipality. The source of the elevated Rn-222 concentrations was a newly discovered reservoir of waterborne Rn-222 originating from distribution-system radium-226 (Ra-226) adsorb ed internal pipe scale deposits. Because the proposed national drinkin g water regulations for Rn-222 require sampling at the origin of the d istribution system rather than at the point of use, the proposed schem e for collection of water samples may not represent actual consumer wa terborne Rn-222 exposure in all cases.