DENVER -- New research may have E-Cigarette users think twice about using the devices.
A study by researchers at Roswell Park Cancer Institute shows the vapors from electronic cigarettes leave behind a potentially toxic residue known as "third-hand smoke."
The residue -- which also occurs in regular cigarette smoke -- clings to clothing, furniture and walls, and it's nearly impossible to get rid of.
Doctors say more research is needed to fully understand exactly how E-Cigarettes affect the body.
"I can't go and tell you it's as dangerous as a cigarette -- we don't know that, it may be less dangerous but how less dangerous? It's unclear," says Dr. David Beuther, pulmonologist at National Jewish Health in Denver. "It's the devil you know vs. the devil you don't know."
Doctors say the only way you can completely avoid any third-hand smoke is simply to not smoke at all.