MINERALOGY CONTROLLED DISSOLUTION OF URANIUM FROM AIRBORNE DUST IN SIMULATED LUNG FLUIDS (SLFS) AND SIMULATED GASTRIC FLUIDS (SGFS): POSSIBLE HEALTH IMPLICATIONS (Invited Presentation)

The recent increase in cardiovascular and metabolic disease in the Navajo population residing close to the Grants Mining District (GMD) in New Mexico is suggested to be due to exposure to environmental contaminants, in particular uranium in respirable dusts. However, the chemistry of uranium-containing-dust dissolution in relevant body fluids, such as those in lungs and stomach, and the role of mineralogy are poorly understood, as is their impact on toxic effects. The current study is focused on the dissolution of respirable-sized U-containing-dust, collected from several sites near Jackpile and St. Anthony mines in the GMD, in two simulated lung fluids (SLFs): Gamble’s solution (GS) and Artificial Lysosomal Fluid (ALF). We observe that the respirable dust includes uranium minerals that yield the uranyl cation, UO₂²⁺, as the primary dissolved species in these fluids. Dust rich in uraninite and carnotite is more soluble in GS, which mimics interstitial conditions of the lungs. In contrast, dust with low uraninite and high kaolinite is more soluble in ALF, which simulates the alveolar macrophage environment during phagocytosis. Moreover, geochemical modeling, performed using PHREEQC, is in good agreement with our experimental results. Further geochemical modeling conducted in simulated gastric fluids suggests extensive dissolution of uranium in the stomach, controlled by the mineralogy of particles present. Thus, the current study highlights the importance of site-specific toxicological assessments across mining districts with the focus on their mineralogical differences.