Cannabis vape cartridges are filled with butane hash oil—that's the honeylike goo extracted from the cannabis plant to produce an intense high. Electricity in the vape pen heats the oil so users can inhale the vapor. But the cartridges also contain additives, like thickeners—which dilute the THC oil without thinning the consistency.

Those products are at the center of intense national speculation. Some health figures suspect that vitamin E acetate, which is found in some thickeners sold online and believed to be in many black market cartridges, is to blame. (Others say leaky cartridges could have been the reason, or counterfeit cartridges sold on the street.)

State regulators, cannabis extractors and budtenders all tell WW the same story: Cartridges with dilutants are on the shelves of Portland cannabis dispensaries. But cartridges with vitamin E acetate aren't being sold in stores—and would have to be labeled.

Dilutants are not sold directly to cannabis shops. Instead, they are sold to companies that put the oil in cartridges that are used in the vaping devices sold at the shops. The Oregon Liquor Control Commission requires that cartridge manufacturers provide a full list of ingredients to the agency.

But Erin Purchase, director of operations for the dispensary Kind Leaf Pendleton, says she pulled 15 vape cartridge brands off her shelves because she doesn't know what's in them. She says stores only receive a blanket label reading "natural and artificial flavors."

"The retailer does not even have access to the 'proprietary' ingredients or the methods behind the extraction done by the processor," Purchase says.

WW talked to four local cannabis retailers. Three of them, who asked not to be named, said they have not discontinued the sale of any products.

Belmont Collective in Southeast Portland told WW it has not discontinued any products, but it did tape the OLCC's press release about the dangers of vaping to its counter.

OLCC spokesman Mark Pettinger says the agency is considering a blanket ban on additives. "Because of the vaping illness crisis," he says, "the OLCC will consider taking whatever action is necessary to protect consumer health, including the recall of tainted product, and banning inclusion of questionable additives into marijuana products that threaten human health and public safety."