DETROIT— Scott Becker was sitting at a conference table conducting a work meeting when the lithium ion battery that powers his e-cigarette exploded in his pocket.

"It was like having a firework go off in your pocket," said Becker, 46, of Washington Township, Mich. "I threw my chair back, I started hitting my pants and my hip. I saw the sparks shooting out of my jeans."

Becker suffered third-degree burns. A year later, they still require treatment three times a day.

Injuries like Becker's are becoming more common, said Karla Klas, managing director for injury prevention and community outreach at the Trauma Burn Center at the University of Michigan in Ann Arbor.

The batteries can explode with enough force to knock out teeth and crack vertebrae if they fail in the mouth of the user.

Scott Becker, 46, of Washington Township, suffered a third-degree burn on his right hip last year when a battery he used in his vaping pen exploded.

"We've been seeing some pretty deep burns," Klas said.

Klas made a presentation on the topic at the American Burn Association's annual conference last month in Boston. While she hasn't heard of any deaths caused by exploding e-cigarettes, an informal poll of representatives from about 20 burn centers around the country tallied almost 300 recent burn cases that required hospitalization, she said.

"Not only are the burns deep, but because of the chemicals that are in the batteries, it's almost like they are having a chemical burn on top of the thermal burn," Klass said.

The Federal Aviation Administration banned the devices from checked baggage because of the fire risk.

Vaping proponents insist the incidents are rare and preventable through proper use of the products and their batteries.

"When used and charged properly, those lithium-ion batteries pose no more of a fire risk than other products that use other similar batteries," said Gregory Conley, president of the American Vaping Association, a nonprofit group that advocates vaping as a way to help people stop smoking. "It is a remote risk that is almost entirely avoidable."

Conley said he worries that exaggerated fears of fires could cause some people to avoid vaping and instead, continue a deadly habit, cigarette smoking. But critics say the problem is real and it's growing.

"Even if it's somewhat rare, these things are so dangerous that when it happens, these are horrific injuries," said Wolfgang Mueller, a Detroit-area lawyer who has sued on behalf of three injury victims, including Becker.

Mueller, who worked as a mechanical engineer before studying law, said the batteries can short-circuit internally because of poor manufacturing or externally by coming in contact with metal in someone's pocket, like coins, keys or jewelry.

"That's what makes it so important for these retailers and manufacturers to warn the consumer," he said.