Though the Golden State likes to think of itself as creating some of the best weed on earth, much of it continues to be tainted with some pretty nasty stuff, including dangerous pesticides heavy metals and mold, according to another recent report.

This week, San Francisco Magazine reported that California cannabis marijuana sold in many dispensaries could be tainted. In the past months, a number of media outlets including Leafly and NBC news have reported similar findings.

Working with scientists at Anresco Laboratories, San Francisco Magazine contends that 80 percent of the product entered at the recent HempCon tested dirty, tainted with mold, pesticides, and harmful solvents. The biggest offenders, not surprisingly, were concentrates.

In states that already sell recreational cannabis, including Colorado, Washington, and Oregon, marijuana has to go through quality-control testing before hitting dispensary shelves, but California won’t adopt its own controls until January. Though guidelines haven’t yet been released, many expect them to be even more stringent than what other states currently allow. But for now, there’s still plenty of cannabis that contains substances you wouldn’t want to smoke.

tainted weed

San Francisco Magazine: A worker at Anresco Labs arranges petri dishes of marijuana being tested for toxins.

Here are a few of the key results…

Pesticides And Fungicides: Mostly present in cannabis extracts, Anresco’s Kyle Borland told San Francisco Magazine, “We’ve seen pesticide levels 1,000 times higher in concentrates than what we might normally find in foods.” Used to control mold, spider mites, and other cannabis gremlins, some of the more toxic products can cause reproductive problems or cancer.

Mold, Fungi, And Bacteria: A fungus found in numerous samples of cannabis flower sold in Bay Area dispensaries could be the same mold that recently sickened cancer patients at UC Davis Medical Center, causing rare lung infections. Because of marijuana’s medicinal value to immune-suppressed patients with AIDS or cancer, it’s of serious concern.

Residual Solvents And Chemical Accelerants: Cannabis concentrates (wax, oil, shatter, etc.) can have residual propylene glycol or butane used in the extraction method. At high levels both are toxic.

Heavy Metals: Although heavy metals like arsenic, lead, cadmium, and mercury are frequently found in water and soil, in high enough concentrations these metals can be dangerous if they build up over time.

Other stories about California’s pesticide problem: