In my last article, Toxic Mold in Tobacco and Cigarettes, I explained how a lot of the tobacco that hits the market for consumers is notorious for being infected with mold (fungus) which can be very harmful to the person who consumes it.

Now I would like to show you how marijuana (cannabis) is another popular smoking product that is well known to contain mold. The main types of mold that affect marijuana: Aspergillus, Penicillium, Cladosporium, Rhizopus, Mucor, and Botrytis. Molds that can cause you to become ill, and cause diseases such as aspergillosis, asthma and cancer.

What you need to understand is that mold loves to eat plants and destroy any type of crop. It doesn’t matter if its vegetables, fruit and yes, even marijuana. Hell, mold will even eat drywall, wood, steel and humans if given the chance.

It is one of the oldest, and most deadly micoorganisms in the world with a voracious appetite that does not discriminate.

Mold also loves hot, and humid environments and over-watered plants. The same conditions that most marijuana growers also prefer. This combination equals the perfect environment for mold to grow and contaminate the crops. explains how marijuana becomes infected with mold:

“Molds like moisture and lack of air circulation. For grow rooms, fans act not only to strengthen stems, but to prevent insects from landing and molds from getting a foothold. Any grower worth his or her salt will make sure that they separate and discard any plants suspected of having mold before harvest.

Most mold actually starts after harvest. If moisture is too high in the drying process, mold will take hold. Some people like to use fruit peels to add moisture or flavor to buds that are too dry, inadvertently infecting them with spores from the fruit. Some less scrupulous growers or black market dealers might try to moisten weed to add weight, then store it in airtight containers, causing mold to occur. I have even known some people who would bury weed bricks in the backyard to “mature” them, intentionally causing mold in the false logic that it would increase potency.”

This image below from CBS News of marijuana under the microscope at the University of New Haven, shows a marijuana leaf covered with dozens of tiny bumps. It’s mold, and someone, somewhere could be smoking similarly contaminated pot and not have a clue.

Heather Miller Coyle, a forensic botanist and associate professor at the university, says all sorts of nasty things not visible to the naked eye have been found in marijuana – mold, mildew, insect parts, salmonella and E. coli, to name a few.

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Reports and pictures of moldy marijuana can be found all over the internet. This is no secret, and I’m sure many people who smoke marijuana have also come across a moldy batch of buds.

Even the deceased pop star, Michael Jackson had a batch of moldy marijuana that was found by investigators after he died. According to the LA Times, police investigating Michael Jackson’s death had mistaken moldy marijuana for “tar heroin” following the pop stars death.

The LA Times had reported:

“Rotting marijuana that Michael Jackson’s family members mistook for heroin briefly caused detectives to look for further evidence of the illegal drug in the pop star’s rented residence during the frenzied 48 hours after his death, according to sources close to the investigation.

Family members told coroner’s officials that they found “tar heroin” in the Holmby Hills home’s master bedroom. Only Jackson and his children had access to the room, according to court records unsealed Thursday. The discovery prompted authorities to obtain a search warrant for Jackson’s house for heroin, hypodermic needles, cutting agents, scales, balloons, condoms, razor blades, buyer lists, and seller lists, among other items, documents show.

But within days, police had ruled out heroin as a factor in the singer’s death, sources close to the investigation said. Lab tests showed that the purported heroin was actually moldy marijuana, sources said.”

Andy LaFrate, founder of Charas Scientific, one of eight Colorado labs certified to test cannabis and regularly finds mold had told Smithsonian Magazine;

“It’s pretty startling just how dirty a lot of this stuff is,” LaFrate says. His team commonly found fungi and bacteria in the marijuana products they tested. But for now it’s unclear just how much marijuana growers need to clean up their product. “Like ourselves, this plant is living with bacteria that are essential to its survival. In terms of microbial contamination, it’s kind of hard to say what’s harmful and what’s not.”

He adds, “You’ll see a marijuana bud that looks beautiful. And then we run it through a biological assay, and we see that it’s covered in fungi. So the questions become: What’s a safe threshold, and which contaminants do we need to be concerned about?”

A 2013 study titled, “Potential exposures associated with indoor marijuana growing operations,” found elevated fungal spore levels on the marijuana they tested.

“A total of 407 fungal spore samples were taken using both slit impactor plates and 400-hole impactors. Both methods identified elevated fungal spore levels, especially during the removal of plants from some of the IMGOs. After plant removal, spore counts increased to levels above 50,000 spores/m(3) with one sample over 500,000 spores/m.

In addition, we found that there was a shift in species between indoor and outdoor samples with Cladosporium sp. the predominant outdoor species and Penicillium sp. the predominant indoor species. We concluded that the potential increase in fungal spore concentrations associated with the investigation and especially removal of the marijuana plants could potentially expose responders to levels of exposure consistent with those associated with mold remediation processes and that respiratory protection is advisable.” (1)

In 1981, scientists at the Milwaukee County General Hospital published a report that found the mold known as Aspergillus fumigatus in 11 out of 12 marijuana cigarettes and evidence of the fungus in the blood of 11 out of 21 marijuana smokers. This is the same common mold that was found on most of the tobacco that was studied by researchers as well.(2)

I had written about how dangerous Apergillus can be in my article, “Aspergillus: One of the most common and deadly organisms in existence.” This toxic mold produces aflatoxins that are associated with both toxicity and carcinogenicity in human and animal populations. The diseases caused by aflatoxin consumption are loosely called aflatoxicoses.

Acute aflatoxicosis results in death; chronic aflatoxicosis results in cancer, immune suppression, and other “slow” pathological conditions

As I mentioned above, aspergillus also causes a group of diseases called aspergillosis. The symptoms include fever, cough, chest pain, or breathlessness, which also occur in many other illnesses such as tuberculosis or chronic obstructive pulmonary disease (COPD), aspergilloma or allergic bronchopulmonary aspergillosis (ABPA).

There was a report released in 1988 that a marijuana smoker had died after smoking marijuana contaminated with marijuana. It reads:

“A 34-year-old man presented with pulmonary aspergillosis on the 75th day after marrow transplant for chronic myelogenous leukemia. The patient had smoked marijuana heavily for several weeks prior to admission. Cultures of the marijuana revealed Aspergillus fumigatus with morphology and growth characteristics identical to the organism grown from open lung biopsy specimen. Despite aggressive antifungal therapy, the patient died with disseminated disease. Physicians should be aware of this potentially lethal complication of marijuana use in compromised hosts.” (3)

I also found this testimonial of a friend’s death that he contributed to moldy marijuana in the comment section of an article during the course of my research.

Mold Safe Solutions Conclusion

It is not only mold that marijuana users should be concerned about. A 2013 study by Werc Shop, that was released in the Journal of Toxicology, found pesticide residues on cannabis are transferred to inhaled marijuana smoke, possibly posing a “significant toxicological threat.”

This article is not to scare people. But to inform them of the dangers of mold and moldy marijuana (cannabis). I personally believe that pure marijuana that has no contaminants is not dangerous. But if marijuana is infected with mold and or pesticides, then it most definitely can be harmful and potentially deadly to the person who consumes it.


  1. PubMed: Potential exposures associated with indoor marijuana growing operations
  2. The Crimson
  3. PubMed: Fatal aspergillosis associated with smoking contaminated marijuana, in a marrow transplant recipient
  4. Other sources can be found via the blue links above

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