The Neurological Impact of Repetitive Low-Level Blast Overpressure Exposure

Area of Science:

• Neuroscience
• Occupational Health
• Biomedical Engineering

Background:

• Repetitive low-level blast overpressure is an occupational hazard for military and law enforcement.
• Unlike high-level blasts, low-level exposures don't typically cause overt traumatic brain injury in isolation.
• Concerns exist regarding cumulative biomechanical stress and long-term adverse brain effects.

Purpose of the Study:

• To review human evidence on the neurological impact of repetitive low-level blast exposure.
• To examine potential mechanistic pathways and clinical manifestations.
• To evaluate neuroimaging and biomarker findings related to occupational blast exposure.

Main Methods:

• Narrative review of human epidemiological, clinical, neuroimaging, and biomarker studies (2010-2025).
• Analysis of blast physics, mechanistic pathways (axonal stress, BBB dysfunction), and clinical domains (cognitive, vestibular, etc.).
• Evaluation of fluid biomarkers and advanced neuroimaging for signs of neural stress and dysfunction.

Main Results:

• Evidence suggests cumulative low-level blast exposure can cause subtle, subclinical neurological effects.
• Neuroimaging and biomarkers indicate astroglia activation, axonal stress, and neurovascular perturbation.
• Repetitive low-level blast exposure alone does not cause neurodegenerative disease.

Conclusions:

• Cumulative low-level blast exposure may modify neural vulnerability, especially with mixed exposures or risk factors.
• Critical gaps exist in exposure quantification, longitudinal data, and dose-response modeling.
• Future research and occupational brain-health surveillance are needed.