The question whether mold material is safe to use, regularly comes up on multiple forums, and there is no more a yes or no answer to the question, than there is about eating wild mushrooms. All molds were not created equal!
Like mushrooms, molds belong to families, and while some are salubrious and even used by us in manufacturing processes, others can be deadly.
All of us have smoked moldy material, whether we knew it or not, because it is all around us, but unless you have a compromised immune system or are allergic to the spores, you don't notice it.
In quantities large enough to create an allergic reaction, or with compromised immune systems however, the results range from a runny nose, to death.
The mold spores are the principle source of allergic reactions, but allergic reactions aside, some of the molds produce aflatoxins that attack our central nervous system and livers. Mold material can easily be removed by filtration, but filtration doesn't remove aflatoxins.
When considering what to do with moldy material, the pregnant question is what kind of mold? What caused the mold is a clue, but the only reliable way to tell, is with a microscope, and I recommend that you do a microscopic examination to determine exactly what you are dealing with.
Locally, due to our short growing season, Botrytis bud rot is the bane of outdoor growers, and because of our high humidity, Powdery Mildew is everywhere.
The good news is that while the spores of both are capable of producing a Type I allergic reaction to those sensitive to them, neither produce know aflatoxins, so simply removing all the spores and mold material, makes it useable by removing allergens, as well as the ghastly moldy taste and smell.
Botrytis is actually the mold that produces Noble Rot in grapes, which is highly prized by wine makers for producing sweet wines. I know of no prized use of ubiquitous powdery mildew and it is known by many other names, some of them not repeatable in polite company.
Of serious concern, and not to be taken lightly, are the Aspergillus and Penicillum molds, which are hard to distinguish from one another with simple microscopic examination, so are generally classified as Pen/Asp types.
They are easy to spot, as they were named Aspergillus because their shape, consisting of a shaft with a head like the religious water flinger the priests use, called an Aspergillum. http://en.wikipedia.org/wiki/Aspergillus_fumigatus
Aspergillus is primarily a composting mold living off dead plant material, while Botrytis and Powdery Mildew target living material.
As previously noted, it has spores everywhere, but poorly cured material is the primary reason for an infestation. It likes to grow in dark damp places.
Aspergillus is the more serious actor when it comes to serious health effects, both from allergic reactions to its spores, invasive colonization, and from its aflatoxins, but Penicillium sp. is known to cause keratitis, external ear, respiratory and urinary tract infections, so it isn't soft and cuddly.
The allergenic effects seen by Aspergillus spores include: Type I allergies; Type III hypersensitivity pneumonitis and others.
Some Aspergillus species are known to produce aflatoxins. A. fumigatus causes allergic bronchopulmonary aspergillosis and allergic fungal sinusitis.
Members of this genus cause a disease called Aspergillosis, which is an invasive infection, colonization, toxicoses or allergy.
Many species grow at body temperature and they are opportunistic pathogens, causing infection in individuals with compromised immune systems.
Many toxins are generated by this genus, however, the full range of effects of these toxins are not well researched at this time. They do fluoresce under ultraviolet light however, so their presence may be detected by examination under a black light inspection lamp, such is used in Magnetic Particle and FPI Non-destructive Inspection techniques.
While not a mold, a bacteria anaerobic conditions created by poor curing practices promotes the growth of, and which has been found in poorly cured cannabis, is the Clostridiums.
The Clostridiums includes C botulinum causing botulism in food, and from which Botox is derived, as well as C Perfringens, which causes food poisoning and gas gangrene, as well as C Tetani, the pathogen causing tetanus.
Soooo, now that you know what to look for, if after examining your moldy material under a microscope, you still want to recover it, here is how we remove Botrytis and Powdery Mildew filaments and spores, as well as any of the Clostridium bacteria that may be present.
Our next step is to extract the essential oil from the plant material, using either an alkane or an alcohol.
If we use hexane or an alcohol, we do the filtration before evaporating off the solvent, or if we extract with butane, we redissolve the BHO in at least ten times its volume in ethanol for filtration.
In industry, I used 0.2 micron cross flow micro filtration units to scrub radio active effluent streams at up to 100 gpm, but for small needs like ours, the syringe filter suffices.
They are readily available relatively cheap on E-Bay, or at reasonable prices at American Scientific, as are the syringes.
Once we have filtered at 0.2 microns, we remove the solvent by one of several methods, and the oil will have no hint of mold flavor or taste.
Since it is the spores that cause the Type I allergic reactions, that hazard is eliminated as well.
Any Clostridiums are removed, so subsequent storage in anaerobic conditions can't provide favorable conditions.
To repeat, filtration doesn't remove aflatoxins, so we don't recommend this process for mold strains that produce them.
The attached read is a good overview on some of the other things you may find in cannabis: