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Walter Armstrong Walter Armstrong

Why Potency Labels on Legal Pot Are Unlikely to Be Accurate

3 Substance

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Marijuana users in Colorado, now able to buy pot legally, have begun comparison-shopping in the standard ways—including checking the labels. The new state-regulated marijuana market requires every pot item to have a label, which includes information about the strain of weed and its THC potency. But some shoppers are in store for a surprise when they get home and toke up: Many of the labels are simply wrong. Don’t blame human error. It may be impossible to know with any confidence a bag of pot’s potency because the science of the system for testing is not up to dealing with the real-world effects on the substance.

Here, Jeremy Daw explains part of the problem:

…to determine the levels of THC, CBD, mold and pesticides on pot, one must completely destroy the bud through incineration. Because accurately testing each and every bud in a pound would therefore mean the complete destruction of that pound, testing facilities must necessarily operate under the assumption that every bud in the pound is more or less equally potent (an improved method of testing would test multiple buds in the pound and average out the results – but such a destructive move would only improve the precision of what is still, fundamentally, a guess).