Portable and discreet vape pens are a very profitable segment of legal recreational cannabis markets. For people who don't want to deal with the unpredictability of edibles but also don't want to smell like they just smoked a joint, these pocket-sized vaporizers are very popular, but people might start going back to joints and pot cookies after news broke that some vape cartridges contain potentially dangerous levels of lead.

"We've seen some issues," Josh Wurzer - founder of the cannabis testing facility SC Labs - told Leafly, adding that the number of hazardous cartridges is relatively small compared to the total number that his lab screens. "Out of the thousands we've tested, we've had a very small portion over the limit. I have heard anecdotally some people have had issues with weird, wonky metal results and a ton of failures."

Part of the reason those cartridges are failing is due to California's strict regulations for screening lead. Any cannabis products that exceed 0.5 parts per million (ppm) are deemed unfit for human consumption. In Washington that number is 1.2 ppm and Oregon hasn't established any limits on lead concentrations.

But while Wurzer says only about 0.5 percent of cartridges fail the lab test, that number is still too high for concerned consumers.

The source of the lead seems to originate in the Chinese factories that produce the vaporizer cartridges for the American market. These factories commonly add lead to metal products to increase their malleability. When these leaded metals are used to produce vaporizer cartridges, the concentrated cannabis liquid inside them may become contaminated by absorbing some of the lead from the metal, says Wurzer.

"Maybe some oil is picking up some of the lead and failing there. We have tested actual empty cartridges and confirmed a number of 'over the limit' hits for lead."

Even the highest quality cartridges, called CCELLs, are failing lead screening, being found with 0.6 or 0.7 ppm lead. And when they do pass, it isn't by very much, often 0.3 or 0.4 ppm lead. A number that is frankly still too high for people like Wurzer.

"If it's two or three parts per million lead, I don't want people smoking that," he said. "I'm glad we're catching it."

Peter Hackett, a vaporizer hardware expert with Air Vapor - a company that imports Chinese made vape cartridges - agrees with Wurzer.



"I don't want any lead in anything," Hackett says. "I don't want 4 percent, not 0.5 ppm. I don't want any in there."

Hackett says his company has ordered new, lead-free cartridges, but they won't hit the market until at least the end of February. Meanwhile, if you live in a legal state outside of California, you may continue to be exposed to contaminated vape cartridges. And if you source your cartridges from the illicit market, there may be no way of knowing how much lead you're vaping.

The CDC says there is no safe level of lead exposure and the highly toxic metal can be deadly.