Why it matters: With the number of vaping-related lung disease cases continuing to rise, the US Food and Drug Administration (FDA) is warning the public to stop using THC vaping products, along with any vaping goods obtained off the streets or from unknown sources.

There have now been more than 1,000 reports of lung injuries identified by the Centers for Disease Control and Prevention. The death toll from the mystery illness stood at seven last month. Now, it has risen to 18 deaths across 15 states.

While the exact cause of the disease is still unknown, federal investigators have linked 78 percent of the cases to THC vaping devices, while just 17 percent of cases involved people using vapes that only contained nicotine. As reported by Gizmodo, recent lab tests showed toxic additives in black market vaping products, which is why the FDC advises also avoiding them.

The FDC also urged people not to modify or add substances, such as THC, to vaping products and recommends youths and pregnant women avoid vapes. It did add, however, that any adults who are using e-cigarettes instead of regular cigarettes shouldn’t return to smoking cigarettes.

“More information is needed to better understand whether there is a relationship between any specific products or substances and the reported illnesses,” the FDA writes. “To help gather and analyze as much information as possible, the FDA is working closely with federal and state partners to identify the products or substances that may be causing the illnesses.”

In California, popular e-cigarette manufacturer Juul is under criminal investigation, and the company has stopped all advertising. Meanwhile, a number of states have banned flavored vapes.