In a very few cases moldy marijuana has resulted in a fatal or nearly-fatal disease called aspergillosis. The Aspergillus mold is very common in nature, but it only attacks people whose immune systems have been compromised. It may stay in the lung and cause an allergic reaction, or it may get into the bloodstream and attack organs all over the body.
Aspergillosis from contaminated, moldy marijuana is not a common disease. There are only a few dozen cases reported in the medical literature. Aflatoxin, a poison produced by a few specific species of Aspergillus, is even rarer in marijuana. But because the infection can be devastating in people who have cystic fibrosis, sarcoidosis, HIV, tuberculosis, or immune systems compromised by radiation or chemotherapy, some basic precautions are worthy of mention:
• Molds of any kind in marijuana are introduced during curing, not during cultivation. Aspergillus, Fusarium, and Penicillium molds attack freshly harvested, wet cannabis. You can’t really tell which kind of mold is in the product, whether it is the relatively benign Penicillium or the potentially deadly Aspergillus, just by inspection with the naked eye.
• The error in curing marijuana that introduces mold is allowing the product to stay too wet for too long. Getting the harvested marijuana to less than 15 percent moisture as quickly as possible eliminates mold.
• Using wet marijuana to make marijuana oil is also problematic. The oil will suffocate many kinds of molds and bacteria, but provides an ideal environment for the growth of the microbes that cause botulism. Occasionally people using marijuana for seizure disorders will be diagnosed with seizure disorders that actually are caused by changes in the way the liver metabolizes Dilantin (phenytoin), which may or may not have anything to do with marijuana use.