By Jill Ellsworth MS, RDN, Tess Eidem, Ph.D. No Comments
As an emerging field in cannabis, contaminant testing remains a gray area for many businesses. The vast differences in state-by-state regulations, along with the frequent changes of previously established rules make testing a difficult, time-consuming process. But at its core, the science and reasoning behind why we test cannabis is very clear – consumer safety and quality assurance are key factors in any legal, consumer market. The implications of federal legalization make cannabis testing even more important to the future of the cannabis supply chain. Understanding the types of contaminants, their sources and how to prevent them is essential to avoiding failures, recalls and risking consumer safety.
When talking about cannabis contaminant testing there are four groups of contaminants: pesticides, heavy metals, foreign materials and microbes. The microbes found on cannabis include plant pathogens, post-harvest spoiling microbes, allergens, toxin release and human pathogens. While all of these can be lurking on the surface of cannabis, the specific types that are tested for in each state vary widely. Understanding the full scope of contaminants and looking beyond state-specific compliance requirements, cultivators will be able to prevent these detrimental risks and prepare their business for the future.
Environmental controls are essential to monitor and regulate temperature and humidity
Beyond just the health of the plant, both medical patients and adult use consumers can be adversely affected by microbial contaminants. To immunocompromised patients, Aspergillus can be life-threatening and both adult use and medical consumers are susceptible to allergic reactions to moldy flower. But Aspergillus is just one of the many contaminants that are invisible to the human eye and can live on the plant’s surface. Several states have intensive testing regulations when it comes to the full breadth of possible harmful contaminants. Nevada, for example, has strict microbial testing requirements and, in addition to Aspergillus, the state tests for Salmonella, STEC, Enterobacteriaceae, coliforms and total yeast and mold. Over 15 states test for total yeast and mold and the thresholds vary from allowing less than 100,000 colony forming units to allowing less than 1,000 colony forming units. These microbes are not uncommon appearances on cannabis – in fact, they are ever-present – so understanding them as a whole, beyond regulatory standards is a certain way to future-proof a business. With such vast differences in accepted levels of contamination per state, the best preparation for the future and regulations coming down the pipeline is understanding contamination, addressing it at its source and harvesting disease-free cannabis.
The risk of contamination is present at every stage of the cultivation process and encompasses agricultural practices, manufacturing processes and their intersection. From cultivation to manufacturing, there are factors that can introduce contamination throughout the supply chain. A quality control infrastructure should be employed in a facility and checkpoints within the process to ensure aseptic operations.
Microbial monitoring methods can include frequent/consistent testing
Cultivators should test their raw materials, including growing substrates and nutrient water to ensure it is free of microbial contamination. Air quality plays an important role in the cultivation and post-harvest processes, especially with mold contamination. Environmental controls are essential to monitor and regulate temperature and humidity and ensure unwanted microbes cannot thrive and decrease the value of the product or make it unsafe for worker handling or consumers. Developing SOPs to validate contact surfaces are clean, using proper PPE and optimizing worker flow can all help to prevent cross-contamination and are part of larger quality assurance measures to prevent microbes from spreading across cultivars and harvests.
Methods of microbial examination include air quality surveillance, ATP surface and water monitoring, raw materials testing, and species identification. Keeping control of the environment that product is coming into contact with and employing best practices throughout will minimize the amount of contamination that is present before testing. The solution to avoiding worst case scenarios following an aseptic, quality controlled process is utilizing a safe, post-harvest kill-step, much like the methods used in the food and beverage industries with the oversight of the FDA.
The goal of the grower should be to grow clean and stay clean throughout the shelf life of the product. In order to do this, it is essential to understand the critical control points within the cultivation and post-harvest processes and implement proper kill-steps. However, if a product is heavily bio-burdened, there are methods to recover contaminated product including decontamination, remediation and destroying the product. These measures come with their own strengths and weaknesses and cannot replace the quality assurance programs developed by the manufacturer.
Microbial contamination on cannabis products represents one of the most significant threats to cannabis consumers, particularly immunocompromised patients who are at risk of developing harmful and potentially fatal infections.
As a result, regulatory bodies in the United States and Canada mandate testing cannabis products for certain microbes. The two most popular methods for microbial safety testing in the cannabis industry are culture-based testing and quantitative polymerase chain reaction (qPCR).
When considering patient safety, labs should choose a method that provides an accurate account of what is living on the sample and can specifically target the most harmful microbes, regardless of the matrix.
1. The Method’s Results Must Accurately Reflect the Microbial Population on the Sample
The main objective of any microbial safety test is to give the operator an indication of the microbial population present on the sample.
Figure 1: MA data collected directly from plant material before and after culture on 3M petrifilm and culture-based platforms.
Culture-based methods measure contamination by observing how many organisms grow in a given medium. However, not all microbial organisms grow at the same rate. In some cases, certain organisms will out-compete others and as a result, the population in a post-culture environment is radically different than what was on the original sample.
One study analyzed fifteen medicinal cannabis samples using two commercially available culture-based methods. To enumerate and differentiate bacteria and fungi present before and after growth on culture-based media, all samples were further subjected to next-generation sequencing (NGS) and metagenomic analyses (MA). Figure 1 illustrates MA data collected directly from plant material before and after culture on 3M petrifilm and culture-based platforms.
The results demonstrate substantial shifts in bacterial and fungal growth after culturing on the 3M petrifilm and culture-based platforms. Thus, the final composition of microbes after culturing is markedly different from the starting sample. Most concerning is the frequent identification of bacterial species in systems designed for the exclusive quantification of yeast and mold, as quantified by elevated total aerobic count (TAC) Cq values after culture in the total yeast and mold (TYM) medium. The presence of bacterial colonies on TYM growth plates or cartridges may falsely increase the rejection rate of cannabis samples for fungal contamination. These observations call into question the specificity claims of these platforms.
The Live Dead Problem
Figure 2: The enzyme is instantaneously inactivated when lysis buffer is added
One of the common objections to using qPCR for microbial safety testing is the fact that the method does not distinguish between live and dead DNA. PCR primers and probes will amplify any DNA in the sample that matches the target sequence, regardless of viability. Critics claim that this can lead to false positives because DNA from non-viable organisms can inflate results. This is often called the Live-Dead problem. However, scientists have developed multiple solutions to this problem. Most recently, Medicinal Genomics developed the Grim Reefer Free DNA Removal Kit, which eliminates free DNA contained in a sample by simply adding an enzyme and buffer and incubating for 10 minutes. The enzyme is instantaneously inactivated when lysis buffer is added, which prevents the Grim Reefer Enzyme from eliminating DNA when the viable cells are lysed (see Figure 2).
2. Method Must Be Able to Detect Specific Harmful Species
Figure 3: The team spiked a known amount of live E. coli into three different environments
Conversely, qPCR assays, such as the PathoSEEK, are designed to target DNA sequences that are unique to pathogenic Aspergillus species, and they can be run using standard qPCR instruments such as the Agilent AriaMx. The primers are so specific that a single DNA base difference in the sequence can determine whether binding occurs. This specificity reduces the frequency of false positives in pathogen detection, a frequent problem with culture-based cannabis testing methods.
Additionally, Medicinal Genomics has developed a multiplex assay that can detect the four pathogenic species of Aspergillus (A. flavus, A. fumigatus, A. niger, and A. terreus) in a single reaction.
3. The Method Must Work on Multiple Matrices
Figure 4: The team also placed TSB without any E. coli onto a petrifilm to serve as a control.
Marijuana infused products (MIPs) are a very diverse class of matrices that behave very differently than cannabis flowers. Gummy bears, chocolates, oils and tinctures all present different challenges to culture-based techniques as the sugars and carbohydrates can radically alter the carbon sources available for growth. To assess the impact of MIPs on colony-forming units per gram of sample (CFU/g) enumeration, The Medicinal Genomics team spiked a known amount of live E. coli into three different environments: tryptic soy broth (TSB), hemp oil and hard candy. The team then homogenized the samples, pipetted amounts from each onto 3M™ Petrifilm E. coli / Coliform Count (EC) Plates, and incubated for 96 hours. The team also placed TSB without any E. coli onto a petrifilm to serve as a control. Figures 3 and 4 show the results in 24-hour intervals.
Table 1: DNA was spiked into various MIPs
This implies the MIPs are interfering with the reporter assay on the films or that the MIPs are antiseptic in nature.
Many MIPs use citric acid as a flavoring ingredient which may interfere with 3M reporter chemistry. In contrast, the qPCR signal from the Agilent AriaMx was constant, implying there is microbial contamination present on the films, but the colony formation or reporting is inhibited.
Table 3: SenSATIVAx DNA extraction can successfully lyse the cells of the microbesTable 2: Different numbers of DNA copies spiked into chocolate
This is not an issue with DNA-based methods, so long as the DNA extraction method has been validated on these matrices. For example, the SenSATIVAx DNA extraction method is efficient in different matrices, DNA was spiked into various MIPs as shown in Table 1, and at different numbers of DNA copies into chocolate (Table 2). The SenSATIVAx DNA extraction kit successfully captures the varying levels of DNA, and the PathoSEEK detection assay can successfully detect that range of DNA. Table 3 demonstrates that SenSATIVAx DNA extraction can successfully lyse the cells of the microbes that may be present on cannabis for a variety of organisms spiked onto cannabis flower samples.
No matter the size of your cannabis greenhouse operation, keeping your plants alive and healthy requires the best possible growing environment. This means greenhouse managers and personnel must frequently monitor the status of environmental conditions and equipment. The sooner someone discovers extreme temperature fluctuations, rising humidity or equipment failure, the more inventory you can save.
Cloud-based remote monitoring system in protective enclosure
That’s why integrating a remote monitoring system into your greenhouse operation can save you time, money and anxiety. Monitoring systems that use cloud-based technology let you see real-time status of all monitored conditions and receive alerts right on your mobile device.
Installing a monitoring system and sensors can be easier than you might think. Here are answers to ten questions to ask before installing a cloud-based monitoring system:
What is required to use a remote monitoring system?
Most remote monitoring systems require an internet or WiFi connection and access to an electrical outlet. Programming is done through a website, so it’s easiest to use a computer for the initial setup. If you don’t have an internet connection at your location, you’ll want to choose a cellular system. Make sure that there’s sufficient signal strength at your site, and check the signal quality in the area before purchasing a cellular device.
2. How do we determine what kind of monitoring system and sensors we need?
A reputable manufacturer will have a well-trained support team that can assess your needs even without a site visit to determine which products are best for your application. If you feel you need them to check out your greenhouse operation,many companies can set up a video conference or FaceTime chat to substitute for being on site.
You will want to provide details about the scope and purpose of your cannabis growing operation. Important factors to discuss include:
Skeletal structure of the greenhouse (metal, plastic, wood, etc.) and the covering material (glass or plastic).
Floor space square footage and height of each of your greenhouses.
Number of greenhouse structures in your operation.
Outdoor climate to determine if you rely more on heating or air conditioning and the level of humidity control needed.
Space dedicated to phases of growth (cloning and propagation, vegetative, flowering) and the microclimates needed for each.
Types of lighting, ventilation and irrigation systems.
Level of technological automation versus manual operation in place.
The monitoring system representative will then determine the type of system that would best serve your operation, the number of base units you will need and the types of sensors required.
Temperature display provides quick view of sensor data
The representative should also be able to provide tips on the placement of the sensors you’re purchasing. For example, to ensure thorough air temperature coverage, place sensors throughout the greenhouse, next to the thermostat controlling the room temperature and in the center of the greenhouse out of direct sunlight.
Note that there shouldn’t be a cost for a demo, consultation or assistance throughout the sales process. Be sure to ask if there are any fees or licenses to keep using the monitoring equipment after you purchase it.
3. Are sensors included with the monitoring system?
In most cases, sensors are sold separately. The sensors you select depend upon the conditions you want to monitor and how many you can connect to your base unit. Certainly, temperature is critical, but there are many other factors to deal with as well, such as humidity, CO2, soil moisture, water pH, power and equipment failure, ventilation and physical security.
For example, humidity has a direct impact on the photosynthesis and transpiration of plants. High humidity can also cause disease and promote the growth of harmful mold, algae and mildew. Sensors can detect changes in humidity levels.
Water pH sensor
Like any other plant, cannabis needs CO2 to thrive, so it’s a good idea to include a CO2 sensor that will signal to the monitoring device when readings go out of the preset range. There are even sensors that you can place in the soil to measure moisture content to help prevent over- or underwatering, budget water usage costs, promote growth and increase crop yield and quality.
Of course, all the critical systems in your growing facility—from water pumps to irrigation lines to louvers—rely on electrical power. A power outage monitoring sensor detects power failure. It can also monitor equipment for conditions that predict if a problem is looming, such as power fluctuations that occur at specific times.
Ventilation systems not only help control temperature, they also provide fresh air that is critical to plant health. Automated systems include features like vented roofs, side vents and forced fans. Sensors placed on all these systems will send personnel an alert if they stop running or operate outside of preset parameters.
To monitor the physical security of your greenhouses, you can add sensors to entrance doors, windows, supply rooms and equipment sheds. During off hours, when no staff is on duty, you can remain vigilant and be alerted to any unauthorized entry into your facility.
4. Do monitoring systems only work with the manufacturer’s sensors?
Not necessarily. For example, certain monitoring units can connect with most 4-20mA sensors and transmitters regardless of the brand. When selecting sensors, you might have a choice between ones that are designed by the manufacturer to work specifically with the monitoring system or universal components made by a third party. If the components aren’t made by the system manufacturer, you’ll want to find out if they have been tested with the monitor you are choosing and if you need to work with another vendor to purchase the parts.
A humidity sensor mounted in a weatherproof enclosure
5. Is a monitoring system easy to set up, or do we need to hire an electrician?
Many monitoring systems are quick and easy to install, and users can often set them up without hiring an outside expert. Look for one that requires only a few simple physical installation steps. For example:
Mount the device to the wall or somewhere secure;
Plug it into an electrical outlet and an internet connection;
Connect the sensors.
You connect the sensors to the base unit’s terminal strip using wire, which is included with many sensors. The range of many wired sensors can be extended up to 2,000 feet away from the base unit by adding wire that can be easily purchased at any home store. It’s a good idea to hire an electrician if you need to run wires through walls or ceilings.
Usually, once you plug in the device and connect the sensors, you then create an account on the manufacturer’s designated website and begin using your device. There should be no fee to create an account and use the site.
If the manufacturer doesn’t offer installation services, ask if they can recommend a local representative in your area who can set up your system. If not, make sure they provide free technical support via phone or email to walk you through the installation and answer any questions you might have about programming and daily usage.
6. Is there a monthly fee to access all the functionality of a monitoring device?
Many web- or cloud-based systems provide free functionality with some limitations. You might have to purchase a premium subscription to unlock features such as text messaging, phone call alerts and unlimited data logging access.
7. Should we get a system that is wired or wireless? Will we need to have a phone line, cable, internet or something else?
Wireless can mean two different things as it relates to monitoring: how the system communicates its data to the outside world and how the sensors communicate with the system.
The most popular systems require an internet or WiFi connection, but if that’s not an option, cellular- and phone-based systems are available.
A hardwired monitoring system connects the sensors to the base device with wires. A wireless system uses built-in radio transmitters to communicate with the base unit. Some monitoring systems can accommodate a combination of hardwired and wireless sensors.
8. Can one system monitor several sensor inputs around the clock?
Once the monitoring system is installed and programmed, it will constantly read the information from the sensors 24/7. Cloud-based systems have data logging capabilities and store limitless amounts of information that you can view from any internet-connected device via a website or app.
If the system detects any sensor readings outside of the preset range, it will send an alarm to all designated personnel. The number of sensors a base unit can monitor varies. Make sure to evaluate your needs and to select one that can accommodate your present situation and future growth.
When a monitoring system identifies a change in status, it immediately sends alerts to people on your contact list. If you don’t want all your personnel to receive notifications at the same time, some devices can be programmed to send alerts in a tiered fashion or on a schedule. Multiple communications methods like phone, email and text provide extra assurance that you’ll get the alert. It’s a good idea to check the number of people the system can reach and if the system automatically cycles through the contact list until someone responds. Some systems allow for flexible scheduling, so that off-duty personnel don’t receive alerts.
9. Do monitoring systems have a back-up power system that will ensure the alarming function still works if the power goes out or if someone disconnects the power?
The safest choice is a cloud-based system that comes with a built-in battery backup that will last for hours in the event of a power failure. Cloud-based units constantly communicate a signal to the cloud to validate its online status. If the communication link is interrupted—for example by a power outage or an employee accidently switching off the unit—the system generates an alarm indicating that the internet connection is lost or that there is a cellular communications problem. Users are alerted about the disruption through phone, text or email. All data collected during this time will be stored in the device and will be uploaded to the cloud when the internet connection is restored.
If you opt for a cloud-based monitoring system, make sure the infrastructure used to create the cloud platform is monitored 24/7 by the manufacturer’s team. Ask if they have multiple backups across the country to ensure the system is never down.
10. What should we expect if we need technical support or repairs to the system?
Purchase your system from a reputable manufacturer that provides a warranty and offers full repair services in the event the product stops working as it should. Also, research to make sure their tech support team is knowledgeable and willing to walk you through any questions you have about your monitoring system. Often, support specialists can diagnose and correct unit setup and programming issues over the phone.
It helps to record your observations regarding the problem, so the tech team can look for trends and circumstances concerning the issue and better diagnose the problem. Ideally, the manufacturer can provide loaner units if your problem requires mailing the device to their facility for repair.
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