Service members need more protection against low-level blast exposure and its potential impact on the brain, a panel of experts testified before the Senate Armed Services subcommittee on personnel.

“Exposure to blast[s] ... can occur both in combat and in training,” Samantha McBirney, a biomedical engineer with the Rand Corp., testified during the Feb. 28 hearing. “Studies have shown that the cumulative effect of repeated low-level blast exposure can cause symptoms similar to traumatic brain injury.”

Between 2000 and 2023, at least 492,167 service members experienced a traumatic brain injury, according to DoD data. The Army accounts for more than half of those traumatic brain injuries, reporting 286,699 cases.

Injuries from low-level military occupational blasts, which DoD describes as blasts generated from firing heavy weapons or explosives in combat or training environments, can go undetected because they are “subconcussive injuries, which are not immediately detectable and would not qualify as a traumatic brain injury,” McBirney said.

Troops exposed to these blasts can suffer from concentration and memory problems, irritability, slowed thinking or reaction time, decreased hand-eye coordination, difficulty hearing, headaches and ringing in the ears, according to DoD.

“Blast exposure over a service member’s career was associated with increased neurobehavioral and post-traumatic stress symptoms following traumatic brain injury,” according to a February 2024 study from the Journal of Neurotrauma.

DoD has taken several steps in recent years to protect troops’ brain health, including creating the Warfighter Brain Health Initiative in June 2022, which coordinates care between the operational and medical communities.

Preventing subconcussive injuries should be a priority, said Frank Larkin, a former Navy SEAL and chief operating officer of the Troops First Foundation. He urged leaders to “get at this early, not wait until it gets to a catastrophic [level], ... [where] the disease process [and] the injury process …have gone too far.” Larkin’s son, Ryan, who also was a Navy SEAL, died by suicide in 2017 after struggling with the effects of four combat tours and an undiagnosed brain injury.

As the military modernizes, the need to protect troops against low-level blasts will only grow, McBirney said. “As our weapons systems continue to become more advanced and increasingly powerful, low-level military occupational blasts will remain an enduring challenge for service members,” she said. “Addressing the issue of repeated exposure to these blasts necessitates action and collaboration between the DoD and the research community.”