In vitro dissolution study of plutonium in aerosol particles from the Mayak PA: a tool for individualised dose estimates

Abstract

Chronic inhalation of Pu particles during Mayak processing is a potential concern for workers. Of the many particle properties that affect individualised dose estimates, particle solubility in lung fluids can be most important. This study compares in vitro dissolution rates of several plutonium industrial compounds present at different stages of the Mayak processing cycle using three different solvents. The results are then used to develop values of absorption parameters for individual dose assessments. In this study, the dissolution rates of nitrate, oxide and mixed plutonium aerosols were determined using a serum ultrafiltrate stimulant (SUF), phagolysosomal simulant fluid and Ringer's solution, all using a static system. According to the results obtained with SUF, Pu nitrate is absorbed into the blood to a larger extent than predicted using model parameters currently applied for Mayak workers. Absorption into the blood of 21.5 vs. 3% of deposited nuclide as current model predicts results in underestimation of systemic burden and overestimation of the lung dose. These data are being used to provide improved retrospective dose assessments for inhaled plutonium aerosols.

Chronic bronchitis incidence in the extended cohort of Mayak workers first employed during 1948–1982

“…The irritating effects of aerosols on the respiratory organs were known to be determined by their physical and chemical properties 22 23. Further, there is evidence in the literature that smoking may strengthen the irritating effects of occupational hazards to respiratory organs 24.…”

Implementation of an In Vitro Experimental Setup Simulating Pulmonary Dissolution Following the Inhalation of Radioactive Particulate Material

“…The compositions of the HBPS, SUF, and PSF were obtained from Sasikumar and colleagues’ study (Sasikumar et al 2017), from Ansoborlo and colleagues’ study from 1999 (Ansoborlo et al 1999) and from Aladova and colleagues’ study (Aladova et al 2007), respectively. The different solvents were prepared in samples of 1 L each, starting from a 700-mL volume of distilled water and sequentially adding the single reagents while magnetically stirring the solution.…”

Simulated biological fluids – a systematic review of their biological relevance and use in relation to inhalation toxicology of particles and fibres

“…However, 239 þ 240 Pu dissolved significantly faster in Gamble's than the modified version (pH 8.2), indicating the effects to be material specific. In an analogous study, Aladova et al (2007) presented the dissolution of Pu in aerosol particles (Pu oxide and Pu nitrate) in other SLFs of pH 7.4. One of these was a modification of Gamble's known as serum ultrafiltrate (SUF) and the other being Ringer's solution, which contains a far simpler salt formulation and practically no complexation agents.…”

“…As described previously, a lysosome will contain proteolytic enzymes and ROS used to digest the engulfed substances, with an acidic pH generally described as being pH 4.5 (see earlier discussions on pH variability within the intracellular compartments). Although the extent of phagocytosis is not completely verified (Dean et al 2017), and will be dependent upon dose and material physicochemical parameters, it has been hypothesised that within 24 h of deposition more than 90% of inhaled materials will be phagocytised by alveolar or airway macrophages (Aladova et al 2007). It is therefore important to also assess materials in this acidic intracellular environment to get an accurate picture of their bioaccessibility and durability within the lung.…”