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Nate Seltenrich, Leafly

In brief: Legal cannabis gets tested for heavy metals in most states. That’s good because we know weed sucks up metals from the ground. And now, researchers have published a link between cannabis use and metal exposure among a group of smokers from 2005 to 2018. Read the details below.

What’s in McGraw’s marijuana metal study of 2023?

Cannabis sativa is what scientists call a hyperaccumulator. Plants in this class, of which there are more than 700 (other members include sunflowers, barley, and tobacco) accumulate metals from soil, water, and fertilizers at levels hundreds or thousands of times greater than average.

But the fact is that most smokers still are not buying from tested sources—and in some legal states the illicit market reigns. In the country’s biggest market, California, an estimated two out of three cannabis dollars are spent in the illegal market where growers don’t test for anything.

But a new study suggests some of those metals may also be accumulating in the bodies of cannabis users—arguably driven by contamination in the illicit markets…