SAN DIEGO -- Pesticides, mold, bacteria -- these are boogeymen that technicians at cannabis testing labs are intimately familiar with and look for daily as part of California's rigorous requirements to legally bring THC products to market.
In the past month, they've increasingly been asked to look for something else: vitamin E acetate.
The synthetic form of vitamin E in black market THC vape cartridges has been linked as a possible contributor to the lung illness outbreak that has swept the nation.
Now, manufacturers in the legal market are doing everything they can to ease consumer worries, including paying higher costs for lab-verified proof that their cannabis-filled cartridges, or "carts" for short, are free of the additive.
But that hasn't been enough for some cannabis consumers -- especially when faced with the recommendation by the Centers for Disease Control and Prevention to refrain from vaping any products containing THC for now.
Some San Diego dispensaries reported a 20% dip in vape sales in the past month, with some customers switching to other delivery systems -- from edibles to tinctures to pre-rolled joints -- until the mysterious source of illness is revealed.
Southern California as a whole has seen the market share of cannabis vaping products contract by 20% since the vaping scare has grown in the past month -- more than in other parts of the state, according to New Frontier Data, a market analysis firm.
The long-term outlook is the "billion dollar question," said John Kagia, the firm's chief knowledge officer.
"It is going to hinge prominently on the findings of the CDC investigation to prove -- what so far is still rampant speculation -- what the culprit is here," he said.
The crisis has legal cannabis markets around the country and in California fighting to distinguish themselves even further from the unregulated illicit market, which so far appears to be culpable for the outbreak.