3 Important Considerations in Cannabis Contaminants Testing

Testing for Contaminants

A paramount process for the safety and quality control of cannabis and cannabis products, all cannabis producers and processors must consider contamination. Major sources of cannabis contamination include: residual solvents from extraction processes, excess moisture and microbial growth, and residual pesticides from cultivation. Each source comes with unique methods for monitoring and detection.

As more states legalize production and an increased number of operations open for business, the potential for contaminants continues to increase. Complex supply chains, such as those involving multiple cannabis handlers at the cultivation and processing levels, as well as storage, transportation, and distribution practices compound these concerns.

Analytical labs perform rigorous testing to ensure cannabis products are safe and are compliant with state regulations. Third-party testing labs provide essential services for cannabis operations to achieve compliance and provide the metrics trusted by their customers. Some cultivators and processors practice in-house testing to be sure products are reliable and safe prior to downstream processing and testing.

Despite these measures, contaminants testing challenges persist. Here we discuss three “C”s of contaminants testing – complexity, compliance, and costs, and the importance these bear on the success of operations.


The complexity issue is multidimensional. First, there is sample complexity. The sample matrix can vary in complexity depending on the location taken from the plant (leaves versus flower for instance), the plant type, growth conditions, and other factors. Furthermore, the preparation method (ground versus extracted) and the moisture content (growth, prep, and storage conditions) can have pronounced effects on the sample matrix. These factors can challenge methods of analysis and therefore require standard procedures to minimize variability. Many regulatory or analytical testing labs specify the type of sample, whole plant versus flower, the preparation methods, and the moisture content of incoming material. Once in the lab, robust methods and instrumentation play major roles in the accuracy and precision of contaminant analysis.

The next dimension is target complexity. Each state has unique testing requirements regarding potency and contaminants. Pesticide regulatory limits or maximum residue limits (MRLs) have thus far been adopted from regulatory bodies such as the USDA, and a panel of pesticides in one state may differ from that of another state. In addition, states routinely change pesticides requirements with respect to the type and acceptable MSLs. Again, analytical methods and instrumentation must be robust to account for the appropriate scope and possible changing conditions of pesticides analysis.

The final dimensional is analytical complexity. Generally speaking, the stricter the regulations, the more complex the methods and instrumentation required for analysis. Many new technologies and products focus on enhancing performance and resolution to better handle analytical complexity. From more thorough preparation and extraction protocols, to better compound separations and detection limits, new products and consumables offer distinct advantages for tightening and evolving cannabis regulations.


In order to achieve and maintain compliance, cannabis operations must demonstrate the ability to produce high-quality, reliable cannabis material. This first step in the process is thorough knowledge of the compliance details relative to the location of operation. Some states have internal compliance programs with performance metrics that must be met. Other states allow use of third-party accreditation programs to verify performance. Yet others require both state and third-party compliance testing.

Another key step is to be aware of changing test requirements and the advent of new testing standards. Awareness of the activities of standards bodies such as AOAC and knowledge of new technologies and products are vital in staying ahead of the compliance curve.

The development of in-house quality control and standard operating procedures are essential factors in helping to maintain compliance and rout out any issues that may arise in the production pipeline. Voluntary routine testing outside the mandates of compliance can offer an additional level of surveillance to unforeseen events.


The costs associated with compromised contaminants testing can be severe. The downstream health effects due to tainted cannabis products can not be imagined, especially for medically compromised consumers. Actual expenses resulting from substandard cannabis sourcing, processing, and/or testing can exceed most people’s expectations. Case in point, Oklahoma regulatory bodies recently shuttered a processing operation and levied a fine in excess of $500,000 for exceeding pesticide limits and other violations. In this particular case, use of third-party products may have contributed to the issue.

Even if monetary costs can be squared, the logistical costs associated with ceasing operations, investigating sources, repairing supply chains, and legally getting back up to speed may be prohibitive.


States are continuing to evolve regulations for contaminants testing. For example, potency and pesticides testing mandates are common, while moisture and microbial testing (such as pathogenic Aspergillus detection) are still gaining widespread enforcement. Independent standards initiatives and federal recommendations are helping to drive methods development and adoption. Absent federal testing guidelines, however, cannabis processors must pay steadfast attention to state compliance details and be aware and knowledgeable of new products and technologies to assist their operations.

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Updated August 2021