Lauren Fish is a research associate with the Defense Strategies and Assessments Program at the Center for a New American Security (CNAS) and former Capitol Hill staffer. Paul Scharre is a senior fellow at CNAS and a former Army Ranger who served in Iraq and Afghanistan.
Traumatic brain injury (TBI) is the signature wound of today's conflicts, affecting more than 370,000 service members, and emerging evidence suggests troops may be exposed to hazards to the brain during training as well.
TBI can come from many causes: falls, vehicle accidents, bullets, shrapnel, etc. In recent years, researchers have begun to understand that the primary blast pressure wave from explosions can also damage the brain, although the specific mechanism of injury from blast pressure is poorly understood.
Most concerning, emerging evidence suggests that service members may be exposed to significant levels of blast overpressure when firing heavy weapons, such as recoilless rifles, even in training.
Recent Defense Department studies have found that blast exposure from firing heavy weapons in training, such as the Carl Gustaf recoilless rifle, is associated with short-term cognitive deficits.
Even when used within currently approved firing limits, DoD studies have demonstrated that some service members may experience short-term deficits in delayed verbal memory, visual-spatial memory, and executive function after firing heavy weapons.
Service member cognitive deficits following a single day of heavy weapons firing in training took 72 to 96 hours to resolve to a level at which they were not statistically significant.
Other DoD studies have found higher rates of concussion and post-concussion associated symptoms among individuals with a history of prolonged low-level blast exposure from breaching and shoulder-fired weapons.
The study's authors concluded that the findings "support the hypothesis that there is a positive relation between the amount of blast exposure and reported symptoms." They noted that those repeatedly exposed to low-level blasts from breaching or shoulder-fired weapons could face "a potential occupational medicine concern."
Animal studies have also provided evidence of the cumulative effects of repeat, low-level blast exposures.
In large animals (such as a pig), three exposures in a day can result in a 30 percent to 40 percent greater physiological change than a single exposure, meaning more exposures lowered the threshold for injury. Additionally, these studies showed 24 hours was insufficient to recover from blast-related effects.
However, research in this area is still nascent, and scientists understand very little about the injury mechanism -- how blast exposure directly translates to these cognitive deficits and symptoms. Scientists need more data to better understand the effect of blasts on the brain.
This gap in data led to a previous deployment of blast gauges worn on soldiers to quantify the exposure, including overseas in combat, but this Army program ended last fall. The DoD is currently studying blast pressure exposure in training when firing heavy weapons.
Enemy-initiated blast events have different pressure signatures, however, making it critical to record data on combat blast events when they occur.
As with other occupational hazards that service members face in the service of their country, the effects of blast exposure will take years to understand.
Vietnam veterans were exposed to the defoliant Agent Orange, which is linked to at least a dozen health problems -- including multiple types of cancer.
Veterans suffering from Gulf War Syndrome, which is linked to unexplained illnesses, including chronic fatigue and fibromyalgia, have struggled to get approval from the Department of Veterans Affairs (VA) for claims. The VA is conducting a follow-up study to better understand Gulf War veterans' health.
Soldiers in Iraq and Afghanistan were harmed in burn pits, which burned all types of trash, including human waste. Studies are ongoing into the long-term effects of this exposure, and the VA is considering compensation on a case-by-case basis.
Unfortunately, in all of these cases, it has taken years for the DoD and VA medical community to fully understand these occupational hazards. In many cases, veterans still struggle to receive the care they require and deserve.
The 2018 National Defense Authorization Act (NDAA) requires a longitudinal study of service member exposure to blast pressure during training and combat.
It is the first step to better understanding blast exposure and possible injury mechanisms. Since TBI can take years to manifest, medical researchers need to record these events now in order to determine which exposure patterns and levels ultimately lead to injury. Collecting the necessary data is the first step to addressing this risk.
The NDAA also requires the DoD to consider the feasibility of a blast exposure log for service members to keep individual records of blast events, which is critical if the VA ultimately determines injury from blast exposure should be covered.
One only needs to look to jump logs, which count airborne parachute jumps, to see the military is already capable of maintaining this type of record over a service member's career.
The American people owe it to those who serve to take care of injuries they received from their military service, including from occupational hazards that may take years to manifest.
This NDAA requirement ensures the DoD is doing all it can to improve its understanding of blast exposure. It also lays the groundwork for current active-duty service members to have a record of their exposure so that if they later develop symptoms, they can receive the proper care and compensation.
In the past, it has often taken decades for the DoD and the VA to understand these health risks and respond accordingly. Congress, on behalf of the American people, should ensure those damaging delays do not occur again.
The NDAA provision will ensure the DoD takes the necessary steps today to supply medical researchers with the data they need to understand the health effects of blast exposure.
-- The opinions expressed in this op-ed are those of the author and do not necessarily reflect the views of Military.com. If you would like to submit your own commentary, please send your article to firstname.lastname@example.org for consideration.