Elemental phosphorus slag exposure study in Southeastern Idaho, USA

Phosphorus slag containing elevated concentrations of radionuclides in the uranium series with radium-226 ranging from 750 to 1100 Bq/kg has been used in Southeastern Idaho communities as a construction material. An exposure study was conducted in the region to identify residences that incorporated phosphorus slag in the construction material, to determine the dose from the slag to residents, and to find slag in public structures and roads. Measurements were made with calibrated, commercial “Micro Rem” instruments and with commercial Al2O3 TL dosimeters. A total of 1472 residences were surveyed, and we estimate that less than 12% of the residences in Soda Springs contain slag; while no houses in Pocatello or Fort Hall were found to have slag in the construction. Individual dose estimates for nine individuals in this study exceeded 1 mSv/year above background, while the highest estimated individual dose was 1.32 mSv/year. Few of the public structures surveyed were found to contain slag. A significant fraction of the public roads, however, contained slag: 27% in Pocatello, 23% in Soda Springs, and 20% in Fort Hall.