Development of age-dependent dose modification factors for acute radiation lethality

Abstract

Purpose: The aim of our work was to develop an approach to account for the impact of age at exposure on acute radiation lethality risk for the purpose of improving casualty estimation tools when applied to a diverse population.

Materials and Methods: Age-dependent radiation lethality data were collected from published animal studies. The 50% lethal dose responses (LD₅₀) were extracted, grouped according to developmental stages in humans and average LD₅₀ values calculated for select age categories. Dose modification factors (DMFs) were developed by dividing LD₅₀ values of non-young, adult groups to the reference adult category within each study. DMFs were combined across each age group to provide a DMF for each age category.

Results: Data from 12 studies with age-dependent LD₅₀ values from 5 species (>21,000 animals) demonstrate increased sensitivity to acute radiation in elderly and young animals compared to young adults. DMFs were developed for infant (0.80), juvenile (0.86), late adult (0.86), and elderly (0.71) populations.

Conclusions: Animal and human data support increased radiosensitivity in infants, juveniles, and aging adults. DMFs provide a mechanism to account for age-dependent variability in health effects models and to determine the impact of age on casualty estimates.

Keywords:

• Acute radiation lethality
• radiosensitivity
• age
• LD₅₀
• radiation dose response

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by the Defense Threat Reduction Agency (DTRA) under contract HDTRA1-14-5-0003/0005.

Notes on contributors

Daniela Stricklin

Dr. Daniela Stricklin is a Senior Science Advisor at ARA. Her expertise is in environmental health and specializes in modeling the health effects from radiation. E-mail: [email protected].

Robert Prins

Dr. Robert Prins is a Medical Physicist at ARA. His research is primarily focused on radiation transport and the resulting health effects. E-mail: [email protected].

Jacob Bellman

Dr. Jacob Bellman is an Applied Mathematician at ARA. His research is primarily focused on the physiological response to injury and the resulting health effects. E-mail: [email protected].