Differences in dissolution behavior in a phagolysosomal simulant fluid for single-constituent and multi-constituent...

Particle dissolution within macrophage phagolysosomes is hypothesized to be an important source of dissolved beryllium for input to the cell-mediated immune reaction associated with development of beryllium sensitization and chronic beryllium disease (CBD). To better understand the dissolution of beryllium materials associated with elevated prevalence of sensitization and CBD, single-constituent (beryllium oxide (BeO) particles sampled from a screener operation, finished product BeO powder, finish product beryllium metal powder) and multi-constituent (particles sampled from an arc furnace during processing of copper-beryllium alloy) aerosol materials were studied. Dissolution rates were measured using phagolysosomal simulant fluid (PSF) in a static dissolution technique and then normalized to measured values of specific surface area to calculate a chemical dissolution rate constant (k) for each material. Values of k, in g/(cm2 day), for screener BeO particles (1.3 +/- 1.9 x 10(-8)) and for BeO powder (1.1 +/- 0.5 x 10(-8)) were similar (p = 0.45). The value of k observed for beryllium metal powder (1.1 +/- 1.4 x 10(-7)) was significantly greater than observed for the BeO materials (p < 0.0003). For arc furnace particles, k (1.6 +/- 0.6 x 10(-7)) was significantly greater than observed for the BeO materials (p < 0.00001), despite the fact that the chemical form of beryllium in the aerosol was BeO. These results suggest that dissolution of beryllium differs among physicochemical forms of beryllium and direct measurement of dissolution is needed for multi-constituent aerosol. Additional studies of the dissolution behavior of beryllium materials in a variety of mixture configurations will aid in developing exposure-response models to improve understanding of the risk of beryllium sensitization and CBD.