Aspergillus in cannabis: The silent threat of a dangerous mould

The ubiquitous presence of moulds

Moulds and their spores are an integral part of our environment, with millions present in the air we breathe daily. While most of these are harmless, certain conditions can make some moulds, especially those on improperly processed or stored cannabis, a significant health risk.

This is particularly true for medical cannabis users, many of whom suffer from chronic illnesses that compromise their immune systems, making them more susceptible to fungal infections.

Aspergillus: A potent threat in cannabis

Among the various moulds that can develop on improperly dried, processed, or stored cannabis, the Aspergillus group stands out as particularly dangerous. Spores from this mould can lead to a condition known as Aspergillosis in immunocompromised patients, which can be fatal.

Beyond the direct health risks, mould contamination also leads to the degradation of the desired active compounds, reducing the medical efficacy of the cannabis.

Smoking and the heat-resistant Aspergillus

A significant concern with Aspergillus is its remarkable heat resistance. Many consume cannabis by smoking, but the temperatures achieved during this process are insufficient to reliably kill the spores.

This means that the spores are directly inhaled into the lungs, the very organ from which Aspergillosis can most aggressively spread. While a healthy individual is unlikely to contract the disease, it poses a life-threatening risk for patients with conditions like HIV or those undergoing chemotherapy, both of which weaken the immune system.

Documented cases and consumption alternatives

Medicinal Genomics, a renowned US platform on medical cannabis, has documented over 20 cases where smoke from contaminated cannabis led to Aspergillosis in immunocompromised patients. It's crucial to understand that this risk is primarily associated with smoking.

If one's immune system is compromised and there's uncertainty about whether the cannabis product has been tested for Aspergillus, it's advisable to consider alternative consumption methods. Oral consumption, such as through baked goods, doesn't transmit this mould. Similarly, pharmaceutically pure cannabis products like Dronabinol are free from fungal spores.

Countermeasures: Testing and irradiation

Medical cannabis producers have been aware of the Aspergillus issue for several years. Almost all states offering medical cannabis test their products for this mould. The United States Pharmacopeia (USP) identifies the qPCR method as the most reliable standardised procedure to detect this dangerous mould.

This PCR test covers all genetic subtypes of Aspergillus. However, a simple home-use rapid test remains unavailable.

In Germany, irradiation of the harvest is employed to control this problem. Over half of the cannabis harvested in Germany undergoes irradiation to kill moulds and other microbes.

Gamma irradiation: A controversial solution

There are two primary irradiation methods: gamma radiation and electron irradiation. Gamma radiation, in particular, is a subject of debate. Critics argue that it produces radioactive isotopes and alters the cannabinoid profile. However, current scientific understanding refutes these concerns.

The dose of gamma radiation used for sterilisation is so low that it doesn't degrade compounds like cannabinoids. Chromatographic analyses of cannabis samples before and after gamma irradiation have shown no changes in the cannabinoid profile, with only minor variations in terpene composition.

The FDA and WHO have deemed food sterilisation through gamma radiation safe, and it's a common practice for many other foods.

The prohibition problem

Beyond medical cannabis, street cannabis is particularly prone to Aspergillus contamination. Patients who resort to easily accessible street cannabis due to the bureaucratic hurdles associated with prescribed medical cannabis might inadvertently expose themselves to this mould.

Depending on their health condition and the primary illness for which they use cannabis, this could lead to fatal Aspergillosis. This risk underscores the need for full cannabis legalisation, ensuring widespread access to quality-controlled products.