Aspergillus is a genus of mold that is commonly found in the environment, including soil, plants, and decaying organic debris. In fact, there are several hundred species of aspergillus! Aspergillus species produce aflatoxins which are a family of mycotoxins produced by certain fungi. These aflatoxins are known as cancer causing substances and pose a dangerous threat to humans and livestock. Although this type of mold is commonly grown underground, the release of its spores into the air is the route of the problem in terms of contaminated product. Given there are many species of Aspergillus that are not harmful, a select few can cause life threatening issues. We aim to cover short aspergillus topics in hopes to educate and clarify conversations surrounding this fascinating fungus.


Aspergillus Exposure

While many species of Aspergillus are harmless, some species can be potentially dangerous to humans. Aspergillus can release incredibly small spores into the air. If these spores reach our sensitive respiratory system, they can cause various health issues. The lungs are a perfect breeding ground for the fungus and can quickly lead to infection. The infection can take a gnarly turn for individuals who have weakened immune systems or underlying respiratory conditions. If the infection is not treated early, it can cause serious and sometimes fatal bleeding in the lungs.

Health Impacts

Breathing in these contaminated spores causes a slew of known health issues. Fumigatus is the most prevalent Aspergillus species of fungus causing disease and is the leading cause of aspergillosis causing chronic pulmonary infections. Aspergillosis is a condition in which fungi infects the tissues. The most common manifestation of Aspergillus infection is allergic bronchopulmonary aspergillosis (ABPA), which is an allergic reaction in the lungs.

Individuals can contract aspergillosis in a surprising way…via organ transplants and stem cell transplants. Aspergillus is the most common invasive mold infection in solid-organ transplant (SOT) recipients, and it is the most common invasive fungal infection among lung transplant recipients. Because of the increased risks of contracting aspergillosis via organ transplants, there are many transplant programs who will remove patients who use cannabis from their donor recipient list.

Concerns for Cannabis Users

Like many other crops, cannabis plants can be susceptible to fungal infections, including Aspergillus. If cannabis is grown or stored in conditions that are conducive to mold growth, such as high humidity or improper drying and curing processes, it can provide an environment for Aspergillus to thrive.

When contaminated cannabis is consumed via the respiratory tract, it can potentially pose health risks, particularly for individuals with weakened immune systems or respiratory conditions. The issue with fungus spores and cannabis is when its spores are introduced into the lungs – smoking and inhaling contaminated product. This is especially concerning if the plant material is tainted with fumigatus spores is introduced into the lungs, which could create a perfect environment for infection. Infused edible products are typically not a concern when it comes to Aspergillus because the stomach is not conducive for the spores to survive.

Known Aspergillus Cannabis Cases

Sadly, there are several studies linking cannabis inhalation use and invasive aspergillosis. Invasive aspergillosis has been described in association with marijuana smoking in two cancer patients on chemotherapy, two leukemia patients, a renal transplant recipient, and a few patients with AIDS. In a 2011 study, chronic pulmonary aspergillosis (CPA) was associated with marijuana smoking. This study detailed the unfortunate case of a patient passing away at just 34 years of age and another patient at 46 years of age.


Given there are many types of illness causing microbiological contaminants, some states have only just required testing for aspergillus. In 2023, new rules were established by the Oregon Health Authority (OHA) that finally involve required microbiological contaminants (including aspergillus) testing for marijuana and hemp products. Specifically, OHA requires testing for these types of Aspergillus molds: pathogenic aspergillus flavus, fumigatus, niger and terreus.

Other states requiring aspergillus testing include Alabama, Alaska, Arizona, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Iowa, Michigan, Mississippi, Missouri, Montana, Nevada, New Mexico, New York, South Dakota, Utah, Vermont, and West Virginia.


Inhaling Aspergillus spores can lead to respiratory problems, allergic reactions, or even invasive aspergillosis. This is why it is important to ensure that cannabis is grown, processed, and stored under appropriate conditions to minimize the risk of Aspergillus contamination. Quality control measures, focus on preventive rather than reactionary, regular testing for molds and other contaminants, can be implemented in the cannabis industry to ensure consumer safety. It’s important to obtain cannabis products from reputable sources that adhere to strict quality standards to minimize the potential risks associated with Aspergillus or other contaminants.

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