Doctors at the University of Washington Region Burn Center in Seattle report a growing number of patients who are being harmed by exploding e-cigarettes. The center has treated 22 people for burns and other injuries caused by exploding e-cigarettes since October 2015. The explosions are caused by lithium-ion batteries in the devices. The batteries can overheat, causing an explosion or fire. “Once we realized this was a trend at our center, we felt the need to get the word out,” Dr. Elisha Brownson, a burn/critical care surgical fellow at the hospital, told HealthDay. “We want consumers to know this is a risk.” The findings are published in the New England Journal of Medicine .