U.S. Transuranium Registry report on the 239Pu distribution in a human body

Area of Science:

• Radiological health
• Human biokinetics
• Nuclear medicine

Background:

• Understanding the internal distribution of radionuclides like plutonium-239 (239Pu) is crucial for accurate dose assessment and health risk evaluation.
• Human biokinetic models are used to predict radionuclide behavior in the body, but their accuracy depends on validated data.

Observation:

• A human whole-body analysis revealed 246 Bq of 239Pu, with 52.8% localized in the lungs and lymph nodes.
• Systemic deposition (47.2%) showed significant concentrations in the skeleton (44%) and liver (42%), with an unexpected high level in the pituitary gland.

Findings:

• The observed distribution suggests an initial plutonium partitioning ratio between skeleton and liver of less than one.
• A proposed initial distribution model indicates 25% to skeleton, 50% to liver, and 25% to other tissues with early excretion.
• Recent biokinetic models demonstrated close agreement with autopsy results, outperforming older models that overestimated deposition.

Implications:

• Accurate human biokinetic models are essential for refining internal dosimetry and improving radiation protection strategies.
• This case study provides valuable data for validating and enhancing models predicting plutonium behavior in the human body.
• Understanding specific organ deposition, like the pituitary, can inform targeted health monitoring and research for exposed individuals.