Under Colorado’s new recreational-marijuana law, all retail pot products—from joints to laced brownies—will have to be labeled according to their potency starting next January.
But pot growers are running into a hurdle: There are no state or industry standards to test marijuana for tetrahydrocannabinol, or THC, the substance mainly responsible for its high-inducing properties.
The labels are intended to inform consumers on the nature of the product they are buying, not unlike alcohol-content labels on beer or wine. But current test results are haphazard, owners of medical-marijuana dispensaries complain, with the same marijuana receiving different marks depending on where it was analyzed.
Laboratory owners acknowledge results vary due to differing methodologies and advise growers not to compare ratings from different labs.