Cover: Neurological Effects of Repeated Exposure to Military Occupational Levels of Blast

Neurological Effects of Repeated Exposure to Military Occupational Levels of Blast

A Review of Scientific Literature

Published Mar 18, 2020

by Molly M. Simmons, Charles C. Engel, Emily Hoch, Patrick Orr, Brent Anderson, Gulrez Shah Azhar


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Research Questions

  1. What is known about the occurrence of repeated occupational blast exposure incurred during military service?
  2. What is the scientific evidence relating to the potential neurological health effects of repeated occupational blast exposure?
  3. What are promising strategies for preventing the potential neurological effects of repeated MOB exposure?
  4. What are promising early detection indicators for the potential neurological consequences of repeated MOB exposure?

Over the past decade, there has been increasing awareness of the central nervous system (CNS) effects of exposure to explosive blast. A key driver of that awareness has been the blast-related injuries suffered during combat operations in Iraq and Afghanistan. With the near cessation of U.S. combat operations in these regions, concern has grown over common, repetitive forms of blast exposure during military service that are, most often, unrelated to combat. An example of such an exposure is routine military training involving heavy weaponry, such as artillery, recoilless rifles, and shoulder-held rocket launchers. These blast exposures are of a lower intensity than those causing acute combat-related injuries; however, repeated exposure may also have impacts on CNS structure, function, and development, as well as on the broader health of military service members.

The authors of this report review the relevant literature on the effects of repeated, military occupational blast (MOB) exposures; prioritize the key research and policy gaps related to repeated MOB exposure; and examine the projects and initiatives that attempt to address those research and policy gaps.

Key Findings

The research team found no generalizable military-wide or service-specific population data (or ongoing studies) from which to estimate the occurrence of repeat, low-level MOB exposure or its potential health consequences

  • The research team identified no research on the overall frequency with which low-level MOB exposure occurs.
  • Most research on the issue of blast-related brain injury is generally concerned with a magnitude of blast exposure that is stronger than low-level MOB exposure.
  • Among animals, studies in mouse and rat models suggest it is plausible that low-level MOB exposure could result in neurological effects.
  • Among humans, completing carefully designed prospective, longitudinal research is essential.
  • There is some evidence that improvements to helmets and improved adherence to hearing protection may mitigate the neurological effects of blast exposure.


  • The authors' main recommendation is to develop and conduct research that advances understanding of the specific health effects of low-level MOB exposure.
  • Epidemiologic and other research is needed to better establish whether low-level MOB exposure poses neurological or other health risks to service members and what, if any, the specific risks are.
  • Implementing aggressive preventive programs against this threat without adequate evidence of preventable injury may yield unintended consequences and require considerable resourcing without commensurate benefit.
  • Other recommendations include the development and testing of preventive interventions, identification of biomarkers, and biosensor validation studies.

Research conducted by

The research described in this report was sponsored by the United States Army and conducted by the Personnel, Training, and Health Program within RAND Arroyo Center.

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