The Importance and Quantification of Plutonium Binding in Human Lungs

Area of Science:

• Radiological Protection
• Internal Dosimetry
• Epidemiology

Background:

• Plutonium exposure poses risks, primarily lung cancer, necessitating accurate dosimetric models.
• Lung dose calculations are highly sensitive to the plutonium bound fraction (fb) in lung tissue.
• Quantifying fb is experimentally challenging but critical for risk assessment.

Purpose of the Study:

• To summarize efforts to quantify the bound fraction (fb) of plutonium in lung tissue.
• To evaluate the impact of fb on lung dose calculations in epidemiological studies of plutonium exposure.
• To corroborate findings on fb through experimental measurements and data analysis.

Main Methods:

• Bayesian techniques applied to human and dog data to estimate fb.
• Analysis of data from Mayak workers exposed to plutonium nitrate.
• Direct measurement of plutonium in respiratory tract tissues of exposed workers.

Main Results:

• Bayesian analysis suggests a small, non-zero fb (< 1%) for plutonium.
• Mayak worker data indicates an fb between 0% and 0.3% for plutonium nitrate exposure.
• Experimental measurements support inferences of a low bound fraction.

Conclusions:

• The bound fraction (fb) of plutonium is small but significant for lung dose assessment.
• Findings support the International Commission on Radiological Protection's consideration of a default 0.2% bound fraction.
• Further studies on plutonium oxide exposure are planned to corroborate findings.