Why Testing Weed for Fungus May Save Your Life

Marijuana with mold on it. (Image courtesy of Marijuana Growers HQ)
Marijuana with mold on it. (Image courtesy of Marijuana Growers HQ)

In a tragic irony, the marijuana several cancer patients used to alleviate side effects of chemotherapy may have been the very thing that made them sicker, and in one case may have been the cause of death.

According to this article from CBS, a rare fungal infection had doctors at UC Davis stymied until they made the connection between the patients’ already compromised immune system – due to intense chemotherapy – and medical marijuana use.

Dr. Joseph Tuscano of the University of California, Davis Cancer Center, noticed that a couple of his patients – including the man who died – had both fallen seriously ill, “It started with a couple patients that were undergoing very intensive chemotherapy and a stem cell therapy, and those patients were very immune compromised,” he said, “What struck me is both of these gentlemen were at least medicinal marijuana users, that helped them with nausea and appetite issues that come with the treatment.” 

Dr. George Thompson, a fungal infection expert with UC Davis Medical Center, agreed, stating, “We thought it was strange to have cases of such a bad fungal disease in such a short amount of time.”

Could a contaminant in the marijuana be a contributing factor, they wondered? To solve the problem, the two doctors decided to pair up to investigate further, only to run into another roadblock: federal law prohibited them from doing that research.

In the evolving landscape of legalized marijuana, one of the biggest issues emerging is the contamination of marijuana flowers with everything from pesticides and mold to dangerous fungi and other airborne pathogens. In several cannabis judging events, large numbers of contenders have recently been disqualified for contamination.

But, testing by legitimate, independent laboratories can find dangerous contaminants, but it can be costly for growers and producers, and isn’t yet mandated. 

The two doctors, knowing they couldn’t do anything more on their own, partnered with Steep Hill Laboratories in Berkeley, where Dr. Donald Land has been analyzing contaminated marijuana for over a decade.

The lab gathered 20 samples of medical marijuana from all over California and pulled out a range of bacteria and fungi found on them, analyzing them down to their DNA.

Dr. Land was surprised by the results, saying, “We were a little bit startled that ninety percent of those samples had something on them. Some DNA of some pathogen.”

Though deeply concerning, these results helped to answer the puzzle of what had been making the patients so ill.

“The cannabis was contaminated with many bacteria and fungi, some of which was compatible with the infections that I saw in my patients,” Tuscano said.

Thompson added, “Klebsiella, E.coli, Pseudomonas, Acinetobacter, these are all very serious infections for anybody in the hospital. But particularly in that population, the cancer population.”

This discovery brought more questions to the table, such as if the method of consuming the weed by smoking made the infection worse because it moved the deadly pathogens directly into the already vulnerable lungs of the cancer patients.

Without the ability to study marijuana further it’s going to remain a guessing game. “But we think now,” Thompson says, “with some of these patients, it’s really unknowingly self-inflicted from cannabis use.”

The takeaway from this unfortunate series of events is that marijuana consumers should check with their dispensary and ask for lab results to know if the weed they’re buying has been tested by an independent lab – their lives could depend on it.

  • Misternomer

    Wouldn’t the contaminants be prevalent on every surface exposed to the air? & wouldn’t breathing the air be the likely source of the infection?
    Or is the article implying that ecoli & the such comes from plants?

    • Liz

      Sometimes a plant will get moldy. And there is a white powder mold- leaf mold. These are cut out by the trimmer. But, the powder mold will dust healthy parts of the plant.

      • Misternomer

        Very different than fatal levels of ecoli.

        • Barfy

          Ecoli for Me coli

      • Sarky Fish

        It’s impossible to “cut out” all mold.

      • Dave Kaylor

        They get washed with a lemon or lime juice mixture

  • Robert Jacobsen

    Why does anyone call marijuana medical ?There is significant legitimate research documenting the massive mind and healthy risks. Why the Drug madness ?.Will Mr Trump soon strike ?Impeach Santa Rosa’s Drug promoting Gang of 7.

    • theseeker1111

      Which research is this? You DO realize the DEA just this week removed dozens of their lies about the “harms” of cannabis because of laws preventing the government from lying to the populace?

  • Sarky Fish

    Misleading article. Already, most oncologists treating patients with chemo will not administer chemo to marijuana smokers. Death by fungal infection can ensue and the majority know it. The claim that the government is preventing studies in this area is patently false. As to so called healthy cannibis smokers, ever notice that persistent cough?

    • theseeker1111

      Hmm. Let’s see… an ever increasing number of hospitals allow cancer patients to use cannabis in their rooms. And many oncologists recommend cannabis as an adjunct to treatment- even in states where it is not legal. (Indeed, the first time I heard of medical cannabis was in 1987 when a friends younger brother was going through Lukemia treatment- and chemo was killing him faster then the cancer. The oncologist recommended cannabis).

      And you are FOS. NIDA/DEA controls the supply of cannabis for research. It is very hard to get approval (and government supplied cannabis) for any research not looking at harms. It is actually easier to get approval for studies using MDMA (ecstasy/xtc) then it is with cannabis.

      And you do realize the largest ever meta-review of studies on cannabis and lung health, done a couple years ago, found not only know long term ill effects but actually found a slight (but statistically signifigant) INCREASE in lung health among heavy users.

      Yes- fungal/mold issues in cannabis can be an issue for those with compromised immune systems- which is why all cannabis should be fully lab tested. But you must also realize that those who are immuno compromised are also advised to avoid countless raw foods because of the same risk.

  • Any form of plant is susceptible to fungi. That’s why it’s critical to understand the role F B I plays in decomp, and prepare SOIL proper. Fungi | Bacteria | Invertibrate… what did you think I mean
    L😄L 🍂

    • Dave Kaylor


  • silverlining

    Some of the organic products to treat for mold ( serenade ) list the active ingredients as forms of bacillus.

  • Zak Carillo

    No differentiation between outdoor and indoor grown, or indoor dirt vs hydroponic grown. Seems indoor growing in clean hydroponic media and using Hepa filters for all the flow through incoming air could eliminate many of these dangerous forms. Of course a controlled indoor environment and good plant housekeeping can also create a situation where mold etc are not likely to ever occur. Too bad these Docs don’t know about stuff like this. It does not take a Pharma Lab to synthesize fake components of MJ to be safe and effective. It does take careful and talented growers who know what to look out for. Note the article says 90% was contaminated, which means 10% was clean. It is that 10% stuff they should look into, and find out why. I already know why, but they did not ask me.

    • theseeker1111

      IRonic statement- given that the experiences in CO,OR, &WA, as well as ancedotal evidence released by some of the labs here in CA, is that the biggest health concern is the level of chemical fertelizers, pesticides, and fungicides- including many that are banned in the cannabis industry, showing up in high levels in indoor cannabis.
      The evidence so far is that outdoor/greenhouse cannabis is generally far safer across the board- but that a (not insubstantial) portion of growers need to learn control practices and not chase peak volume but peak quality- and remove diseased plants.

  • PJ

    These patients should be consuming edibles and concentrated oils instead of smoking.

    • theseeker1111

      Hmm- I disagree with this statement. First off, regardless of the debate as to whether various concentrating methods kill off various molds, we DO know that all concentration methods will also concentrate most chemical pesticides/fungicides/fertelizers present- which is potentially as large or a larger risk to many patients.

      Second, many patients do not want an eedible that takes 2hrs to kick in and lasts for many hours, and many do not want a super concentrated form of cannabis oil that is hart to titrate a proper dosage for their needs.

      • PJ

        Sorry, there was an unwritten implication that patients should not be consuming any untested medicine. I was simply stating other methods that most experienced cannabis providers and consumers would acknowledge as generally less hazardous than smoking. Small, measured and easy to dose edibles (THC and/or CBD) have been around for several years now. These generally act more quickly and according to dosages, last as little or long as a patient might want. Also, dosing from concentrated cannabis syringes that measure down to one tenth of a gram isn’t that difficult either. Finding a desired dosage does, however, take a little experimentation. Most advise patients to start off at very low dosages and increase slowly if necessary.

  • Stewart Williams

    Instead of city and county officials only focusing on getting their hands on some of the money associated with marijuana, how about focus more on the quality of the marijuana that is grown and sold. Mold and fungi are common issues with growing marijuana. When you have thousands of dollars at stake, many will mix in the contaminated junk to maximize profits. There should be more focus on quality control than the legalization and taxation of it.

    • theseeker1111

      Uner MCRSA and Prop 64 ALL cannabis sold in this state will have to go through lab testing for mold and other contaminants, pesticide residues, as well as potency.

      As we have seen in other states- it does take time and money to get labs certefied and in compliance. As we already know with the labs we have- not all are created equal and there is a strong financial incentive for labs to return high potency/low mold/pesticide results.

  • theseeker1111

    It is a shame our local lab (pure anaylitics) is incapable of giving a hard and fast number when testing for molds, instead just giving a result ranging from none detetecded to severe).

  • Art Perez

    I wont say I told you so!!! But I did!

    • itsmesucka707

      Lmao….I wonder what you look like….for some reason i picture a pot bellied fat man that considers himself “husky” has a quite a few health issues stemming from that,possible high blood pressure, some hair but balding, umm you probably drive some sort of truck. O wait u wear a hat too! Oh and your a meat and potato guy! Am i close? (: