DAVID GREENE, HOST:
There's a new report out today that finds that people in the military may be putting their own brains at risk when they fire certain high-powered weapons. Here's NPR's Jon Hamilton.
JON HAMILTON, BYLINE: They look like bazookas, and they're good at jobs like blowing up an enemy tank.
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UNIDENTIFIED PERSON: Rocket.
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HAMILTON: But Paul Scharre, at the Center for a New American Security, says there's a downside to this sort of weapon.
PAUL SCHARRE: When you fire it, the pressure wave feels like getting hit in the face.
HAMILTON: Scharre should know. He was an Army Ranger in Iraq and Afghanistan. Now he's a co-author of the center's new report, "Protecting War Fighters From Blast Injury." The report was commissioned by the Army. It looks at injuries caused by blast waves, pulses of high-pressure air that come from an explosion. The blast wave from a bomb can damage a person's brain without leaving any visible sign of injury. And Scharre says there's growing evidence that the blast wave from certain weapons can also affect the brain.
SCHARRE: If you're looking at a large antitank rocket that a soldier would carry on his or her shoulder, that's now a pretty large explosion, and it's happening right next to your head.
HAMILTON: Scharre says small studies have found that people who fire these weapons repeatedly can experience short-term problems with memory and thinking.
SCHARRE: If you're exposed to these weapons throughout the course of your military career, this might have some subtle and insidious long-term effect that doesn't materialize until later.
HAMILTON: Might. No one knows, and a definitive answer is years off. Even so, the report says military officials should make changes now. It recommends much wider use of devices known as blast gauges. They're about the size of a wristwatch and are usually worn on a service member's helmet and upper body. Scharre says the gauges offer a way to quantify exposure to blast waves.
SCHARRE: Every service member who is in a position where he or she might be exposed to blast waves should be wearing these devices. And we need to be recording that data, putting it in their record and then collecting that data in a database for medical studies.
HAMILTON: The report also recommends reducing the number of times a person can fire certain weapons in a single day and over several days, and it suggests efforts to develop helmets that protect against blast waves. The report's findings are no surprise to Kyle Sims, a former Army medic who helped deploy the first blast gauges in Afghanistan. Sims says he realized something disturbing while studying brain damage in football players.
KYLE SIMS: Holy cow. It's not that one time that the guy got knocked unconscious. It's the 500 times the guy got hit prior to that that he didn't get laid out on a field.
HAMILTON: So repeatedly firing a heavy weapon might be as risky as being knocked out by a roadside bomb. Sims is most concerned about service members involved in training others to fire these weapons. He says one retired officer told him about a day when he'd been exposed to more than 100 blasts from antitank weapons.
SIMS: When he got done talking, I said, well, don't tell me. Let me guess how you felt. At the end of the day, you felt nauseous. You had a headache. You felt tired. All you wanted to do was go take some Motrin, lay down and go to bed. He's like, yeah. I was like, well, that's typical post-concussive symptoms there, buddy.
HAMILTON: Sims says the military should treat blast waves like radiation. That means first measuring the exposure and then setting limits. An Army spokesperson said the military is reviewing the report and will offer a response and recommendations. Jon Hamilton, NPR News.
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