Is micronuclei yield variability a problem for overexposure dose assessment to ionizing radiation?

Area of Science:

• Radiation Biology
• Cytogenetics
• Biomonitoring

Background:

• Micronuclei (Mni) scoring in lymphocytes is a promising alternative to dicentrics analysis for biological dosimetry after radiation overexposure.
• Challenges include interpreting Mni rates at low doses due to individual variability and background frequency, and processing large sample numbers during emergencies.

Purpose of the Study:

• To optimize the micronuclei assay for faster scoring and improved interpretation in biological dosimetry.
• To establish a reliable dose-effect relationship for gamma irradiation using Mni analysis in a cohort of healthy individuals.

Main Methods:

• Comparison of two techniques to enhance micronuclei yield in binucleated cells after gamma irradiation (up to 6 Gy).
• Assessment of Mni response in 47 healthy male blood donors exposed to gamma radiation (0-4 Gy) to build a reference curve.
• Statistical analysis to fit a dose-effect relationship and determine background incidence.

Main Results:

• Optimized micronuclei assay techniques were evaluated for efficiency and yield.
• A realistic dose-effect relationship for gamma irradiation was successfully fitted using data from 47 individuals.
• The calculated background incidence of Mni was higher than anticipated, increasing the detection limit for overexposure to 0.32 Gy.

Conclusions:

• The refined micronuclei assay provides a more robust method for biological dosimetry, particularly for detecting radiation overexposure.
• The established dose-effect relationship and improved detection limit enhance the utility of Mni scoring in emergency scenarios.
• While individual radiosensitivity poses challenges, a standardized approach with a larger cohort can yield reliable dose-response data.