Lung injuries tied to e-cigarettes may have more than one cause, according to the Centers for Disease Control and Prevention (CDC). Many different substances and product sources are under investigation, the agency said.

There have been 1,299 lung injury cases associated with the use of e-cigarettes as of October 8, and 26 deaths have been confirmed in 21 states, the CDC said.
Investigators say vaping oils containing THC, the psychoactive ingredient in marijuana, is especially risky, Reuters reports. No specific product or compound has been tied to the cases.

“I think there will be multiple causes and potentially more than one root cause,” Dr. Anne Schuchat, principal deputy director of the U.S. Centers for Disease Control and Prevention (CDC), told reporters. She noted the source of the illness may vary in different parts of the country.