A popular marijuana-alternative is taking the country by storm, and it can be hard to turn away from an up-and-coming industry. But growing concerns from law enforcement have shown that some of the substitutes may not be so different after all.

Cannabidiol (CBD) is on its way to becoming a $16 billion industry by 2025, with users looking for ways to ease ailments like anxiety, restlessness and sleep loss. Users take it in many forms, from pills to lotions to coffees, but those that are handling it in vape form may want to stay wary.

Investigators are beginning to take a hard look at vaping products following rampant health problems, but what has caught the attention of some is one of the ingredients that you won’t find on the label.

What began as law enforcement agencies trying to curb the use of dangerous cartridges turned into a hunt for criminal activity. Authorities, mostly in the South, tested over 350 products that claimed to contain only CBD. More than 128 of the samples actually contained significant amounts of marijuana, usually in the form of synthetic strains, and often no CBD at all.

Synthetic marijuana comes in thousands of dollars cheaper per pound than CBD, which has led to companies using it as filler in vape cartridges. Just because it’s a manufactured form, doesn’t make it any less illegal. Knowingly dealing in the synthetic stuff can still lead to serious consequences, running all the way up to federal charges.

Like any booming industry, regulations are trying to play catch-up and governing bodies are having a hard time controlling the flow of products onto the market. Companies looking to cash-in are rushing their wares to store shelves, but the merchandise may wind up doing more harm than good.