Eight people have now died and 530 are hospitalized with vaping-linked illness. Some TV networks have stepped up to say they will stop accepting advertising for the products, Michigan and New York have banned flavored vapes, and now Walmart says it will stop selling all e-cigs in its stores.

Some experts suspect black-market marijuana vaping cartridges are to blame and the CDC has activated it’s Emergency Operations Center, signaling that they see vaping as a serious health threat:

“CDC has made it a priority to find out what is causing this outbreak of e-cigarette or vaping-related injuries and deaths,” said CDC Director Robert Redfield, M.D. “Activation of CDC’s Emergency Operations Center allows us to enhance operations and provide additional support to CDC staff working to protect our Nation from this serious health threat.”