(Editor's note: This is the second of two columns focused on pathogens and cannabis.)

Mold is everywhere. It’s on the food we eat, in the air we breathe -- and according to a 2017 study conducted by physician researchers at the University of California Davis Medical Center in Sacramento, 90 percent of the 20 medical cannabis samples purchased from dispensaries throughout the state tested positive for bacteria and fungi. The study was organized after a man being treated at the medical center for what was believed to be curable cancer suddenly contracted a rare fungal disease and died. Physicians were certain the disease was caused by contaminated cannabis, and their findings coincided with this.

Immunocompromised individuals, like the aforementioned, are especially susceptible to serious illness if ingesting fungus-ridden moldy cannabis. Even healthy individuals can experience acute symptoms such as asthma, coughing, vomiting and nausea.

I, along with several current and former medical cannabis industry employees, have spoken about this issue publicly on the radio, in print, at cannabis rallies and in front of the Cannabis Control Commission during their earliest public listening sessions. But as public attention shifted to the race for recreational cannabis licensing, and away from the sins of several businesses found to be selling contaminated cannabis to medical patients, bringing awareness to this issue has been difficult.

Now that this same cannabis is being consumed by a much larger population in the wake of recreational sale, it’s important to bring this closeted public health hazard back to the forefront for those who weren’t privy to the early controversies of medical cannabis’ arrival in the commonwealth. The lack of oversight by governing agencies has left the responsibility of reporting contaminated grows in the hands of those familiar with the nuances of cannabis.

Widespread cannabis contamination was rarely an issue before the advent of mega-grow facilities, housing tens of thousands of plants, packed on top of each other in humid flowering rooms. Any personal grower can attest to the difficulty of containing mold and mildew on just six or seven plants, so imagine attempting to contain and control 20,000 infested plants.

The increase in mold-ridden cannabis in commercial grow facilities could potentially be attributed to factors including stressful conditions for the plants -- such as high heat, humidity, lack of airflow and most commonly, a non-hygienic environment. Maintaining a sterile grow space is sustainable in one’s own personal garden, but with some of the larger facilities housing hundreds of employees going in and out of the building all day, it’s impossible to ensure each one has disinfected themselves by changing clothes, washing their hands and passing through an air shower.

Hundreds of different mold strains could potentially find their way into cannabis, but the most common is powdery mildew or PM -- every cultivator’s nightmare.

Powdery mildew can render an entire crop destroyed. It often occurs later in the flowering stage, making it impossible to completely kill. This can result in the loss of exorbitant amounts of money for large commercial grow facilities.

And this is where things take a dangerous turn in legal cannabis’ journey from seed to sale.

If one plant is found to have PM in a grow room of 300 flowering plants, and not quarantined immediately, it can spread to the other plants at a stunning pace -- destroying an entire harvest and costing a business hundreds of thousands of dollars. In a small, personal garden of seven plants, powdery mildew can easily be remedied with safe treatments such as milk or baking soda -- but when you have 25,000 plants, much stronger fungicides are often the only hope of masking contaminated product and getting it onto shelves.

The number of organizations shut down each month in Colorado upon testing positive for banned pesticides has grown exponentially, and already in the commonwealth several dispensaries have seen a similar demise.

Unable to afford losing entire harvests, large grow facilities have resorted to practices such as “peroxide dipping” to mask the mildew for testing. In more serious cases, the very dangerous pesticide Eagle 20 is being used. Eagle 20, a petroleum-based fungal pesticide, is easily the most commonly used pesticide for facilities battling major powdery mildew infestations.

While Eagle 20 is approved for use on some fruits, the key ingredient, myclobutanil, can transform into hydrogen cyanide when burned. Since consuming an apple doesn’t require a flame, Eagle 20’s dangers are much different when used on cannabis, which is typically ingested by smoking it.

So, by this point you’re probably wondering how you can avoid consuming moldy cannabis.

Although it’s impossible to know if your bud is 100 percent clean without having it tested independently, there are some precautions which can be taken as a first defense. Invest in a 10X magnifying glass -- look at the buds closely for white powdery spots. A black light will also illuminate many mold strains. Moldy cannabis will smell musty and taste like hay, with none of the familiar taste of quality product. If the cannabis has been treated using a hydrogen peroxide bath, you will feel a numbness in your mouth and will most likely get a headache after smoking. Some of the more-serious symptoms of moldy cannabis are chest pains and allergic reactions close to the time of consumption.

The best way to combat the commercial sale of contaminated cannabis is to know the signs, read testimonials online, be mindful of your health prior to ingesting cannabis purchased from unfamiliar sources -- and always speak up if you’re feeling off prior to ingesting cannabis, regardless of whether it is smoked or ingested in edible form.

Remain vigilant. Testing laboratories continue to fail us, and grow facilities aren’t exactly eager to report contaminated batches. The bulk of the responsibility has unfortunately been placed on the consumer; therefore the consumer must know the tell-tale signs of hazardous products. And as always, I will keep my ear to the ground.

Gregg Padula is an employee of GateHouse Media New England. He has experience in several areas of the cannabis industry, and now serves as an advocate for both patients' and workers’ rights. He can be reached at gpadula@wickedlocal.com.