TENORM aerosols in the Florida phosphate industry—assessment of lung fluid solubility and annual effective dose to workers

Inhalation exposure to workers in the Florida phosphate industry due to TENORM aerosols has not been adequately addressed owing to lack of aerosol information. One of the more critical factors is the absorption rate of inhaled radionuclides into blood. In this study, this parameter was characterised using an in vitro dissolution test. The solubility data and other aerosol information were then used for individualised dose assessments at six different Florida phosphate facilities. The solubility data support the selections of ICRP Publication 66 Type M for uranium and lead isotopes and Type S for thorium isotopes. Total annual effective doses are 0.34 +/- 0.12 mSv at granulator areas, 0.30 +/- 0.10 mSv at storage areas and 0.23 +/- 0.02 mSv at shipping areas. These findings are considerably lower than originally postulated in previous studies where no site-specific information on particle size and lung fluid solubility had been available.