Thirty-nine percent of Oregon cannabis users say they consumed pot using a vaporizer pen in the past year.

That finding by Portland polling firm DHM Research and communications firm Quinn Thomas hints at the massive stakes behind an Aug. 3 announcement by the Oregon Health Authority: An Oregonian died in July from a severe respiratory illness related to vaping, and that person had gone shopping at a cannabis dispensary.

The case fits into a larger national epidemic of similar respiratory illnesses linked to vaping. OHA has reported two cases. The Centers for Disease Control and Prevention put the number of similar e-cigarette cases at 450, including five reported deaths.

All the national cases reported that patients showed up at the hospital with severe lung inflammation, chest pain and a cough after using a vaping device. Essentially, the patients were suffocating.

No one knows what exactly killed the Oregonian—just that the person inhaled cannabis oil through a vaping device. But Oregon's case stands out for one reason: The victim bought products from two licensed cannabis dispensaries before dying.

That does not necessarily mean a product bought from one of the stores killed the person—the victim could have added other substances to the vape pen—but it raises huge questions for a cannabis industry that has been allowed to expand rapidly with little interference from state regulators.

Beau Whitney, an economist who studies the cannabis industry, says the national investigation and the lack of a clear culprit in the spate of mysterious lung illnesses presents an "existential threat" to the vape pen and cartridge market.

Whitney thinks the investigation will prompt the state to tighten regulations. "There's going be some type of strengthening of the rules associated with vape pens," says Whitney, "but we just don't know where."

The widespread popularity of vaping among cannabis users adds urgency to solving the mystery of what element in vapes is proving fatal.