A biokinetic model for carbon dioxide and bicarbonate.

Area of Science:

• Radiological Science
• Biokinetics
• Environmental Health

Background:

• Radiocarbon (carbon-14) intake occurs via inhalation (carbon dioxide) or ingestion (bicarbonate).
• Accurate biokinetic models are crucial for estimating internal radiation doses.
• Existing models may not fully capture radiocarbon's complex behavior in the human body.

Purpose of the Study:

• To develop and present a new systemic biokinetic model for radiocarbon.
• To refine parameter values for carbon retention and excretion based on empirical data.
• To compare model predictions with established radiological protection guidelines.

Main Methods:

• Utilized data from human studies involving radiolabeled bicarbonate injection and carbon dioxide inhalation.
• Incorporated data from animal studies with radiolabeled bicarbonate, carbonate, and carbon dioxide.
• Developed a systemic model to describe time-dependent distribution and retention of carbon.

Main Results:

• Parameter values for early retention and excretion were derived from human subject data.
• Tissue distribution and long-term retention data from animal studies informed the model.
• The new model's predictions significantly differed from International Commission on Radiological Protection (ICRP) models.

Conclusions:

• The presented biokinetic model provides a more detailed and potentially accurate assessment of radiocarbon fate.
• Findings suggest a need to review and potentially update current biokinetic models for radiocarbon.
• This research contributes to improved internal dosimetry for radiocarbon exposure scenarios.