The cannabis industry is growing at an unprecedented pace, driven by the legalization wave across the globe. However, as the market expands, so too does the need for robust testing to ensure the safety, quality, and consistency of products. 

Testing is a crucial safeguard for consumer health, but it faces significant challenges. From inadequate standards to economic pressures that compromise testing integrity, the path toward reliable cannabis testing is far from straightforward.

This subject is one of immense personal and professional importance to me, as I’ve worked closely with the Association of Cannabinoid Specialists to address cannabis testing and quality. As a board member, I have been deeply involved in these efforts because ensuring rigorous testing is vital to our mission of delivering quality patient care. Protecting our patients and our profession is a top priority, but we also recognize the need to provide clear guidance to our broader audience of health care providers, educators, researchers, regulators and legislators. Our work in this area helps inform both the public and healthcare professionals about how to safely and effectively approach cannabis use.

Below, I explore some key aspects of cannabis product testing, incorporating insights from recent literature, to paint a clearer picture of the industry’s current state and its future needs.

Effective Testing for Contaminants and Byproducts

Cannabis, like any agricultural product, is susceptible to contamination. Pesticides, heavy metals, residual solvents, and mycotoxins are among the most common threats. Each contaminant requires different methodologies for identification and quantification.¹ For instance:

• Pesticides and heavy metals are best identified through techniques such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS).
• Residual solvents, such as butane or ethanol from extraction processes, are analyzed using gas chromatography (GC).
• Mycotoxins, toxic chemicals produced by mold, often require enzyme-linked immunosorbent assays (ELISA) or liquid chromatography techniques for effective detection.

Further, products that are hemp-derived and then chemically altered after extraction (called semi-synthetic products) can be contaminated in the chemical conversion steps.  These conversions are often done in less-than professional environments by chemists with little experience with purification of products for human use.  Byproducts of the reactions and isomers of the target molecule are common and not easy to identify or remove.

At present, testing inconsistencies persist due to the absence of universal protocols, leading to variability in the contaminant levels detected across laboratories. These inconsistencies could have consequential impacts on consumers, particularly those relying on cannabis for medical purposes.

Accurate Testing for Cannabinoid Levels

Cannabinoid profiling is critical, particularly for medicinal users who depend on predictable THC and CBD levels for therapeutic outcomes. High-performance liquid chromatography (HPLC) remains the gold standard for quantifying cannabinoids because it avoids heat processing, which preserves the natural state of cannabinoids. Despite this, discrepancies between reported and observed cannabinoid levels are troublingly common.

For example, a study analyzing products from dispensaries revealed that average THC content was 23.1% lower than the lowest reported label value, highlighting a lack of standardized protocols and potential economic motivations to inflate potency figures.² Similarly, systematic differences between laboratory-reported cannabinoid levels have been observed, with some labs consistently reporting higher THC content for economic gain.³

The economic consequences of these discrepancies should not be ignored, as prices for cannabis products are closely tied to potency, driving a consumer preference for higher-THC products.

Testing for Biological Contaminants Like Mold and Bacteria

Biological contaminants such as mold present a clear health risk, particularly to immunocompromised individuals. Mold testing, typically done through culturing methods or DNA-based polymerase chain reaction (PCR), is widely regarded as essential.¹  However, there is debate about the best methods of detection: several companies are advocating for the cessation of mold cultures in favor of their proprietary PCR tests.  While PCR is less costly it fundamentally lacks the ability to detect mold species that are not specifically included in the assay and will miss many potentially pathogenic species of mold that have yet to be identified.

The necessity of routine bacterial testing remains a contentious issue. Critics argue that soil or plant-associated bacteria are largely benign, while testing resources might be better focused on dangerous pathogens, such as Salmonella or E. coli. Even pathogenic species like Salmonella and E. coli are unlikely threats as ordinarily people do not eat raw cannabis, and processes like vaporization, smoking, or chemical extraction of cannabis kill such bacteria.  A more targeted approach could strike a balance between safety and cost-effectiveness.

Trustworthiness of the Certificate of Analysis (COA)

Certificates of Analysis (COAs) serve as a key tool for consumers seeking information about a product's cannabinoid profile and contaminant levels. However, COA reliability is compromised when testing is conducted by labs paid by the product manufacturer. This has created a conflict of interest, as labs have felt financial pressure to produce favorable results to retain clients.¹

Currently consumers are being forced to take a proactive approach by seeking out third-party testing from reputable laboratories with demonstrable independence. However, it is fundamentally unfair and unreasonable to put this burden onto consumers and even more so onto patients.  Strong government uses regulation to ensure that products are safe for human consumption and similar strong regulation must be enacted in the cannabinoid space for that purpose.

The Problem of Lab Shopping

Lab shopping is a practice where growers and producers select laboratories known to deliver results aligned with their preferences, such as higher THC readings or no detection of contaminants. This incentivizes some labs to compromise their testing integrity, leading to a "race to the bottom" in terms of reliability. Analysis shows distinct spikes in THC levels just above certain market-favored thresholds (e.g., 20%), a trend likely driven by economic benefits of higher-potency products.³

Reforms requiring randomized lab assignments or blind samples could curb this unethical practice and restore trust in the testing system.

Politics and Regulatory Influences on Testing

The cannabis industry operates under a fragmented regulatory landscape, with testing standards varying across jurisdictions. Political and economic pressures often shape these standards, sometimes prioritizing market interests over consumer safety. For example:

• Some states mandate rigorous pesticide screening and reject entire batches if contamination is found, while others lack robust enforcement mechanisms.⁴
• Industry lobbying may influence regulatory decisions, delaying the adoption of universal protocols.

A push toward harmonized national or international standards is critical to ensure fairness, accuracy, and safety across the board. Standardized testing methods and certification processes could eliminate the variability that currently undermines consumer trust.

Additional Considerations

Several other factors complicate cannabis testing:

• Batch-to-batch variability: Even within a well-tested product line, nutritional and chemical profiles can vary due to differences in growth conditions or processing methods.⁵
• Within batch variability: Even within batches, cannabis flower can be variable depending on the flower’s location on the plant. Testing and sales of cannabis flower by pre-grinding and homogenization solve this problem and lead to more consistent chemical profiles.
• Edibles and concentrates: Products like edibles are particularly challenging to test given their non-homogenous nature, which can lead to inaccurate cannabinoid-level reports.
• Cost barriers: Smaller producers face significant financial challenges in meeting rigorous testing requirements, further widening the gap between large and small cannabis businesses.⁴

Building a Safer Future for Cannabis Testing

Ensuring the safety and quality of cannabis products is a collective responsibility involving regulators, producers, and independent laboratories. The current gaps in testing protocols and enforcement highlight the urgent need for standardized frameworks grounded in robust science. By resisting economic pressures and prioritizing consumer safety, the cannabis industry, including both medical and non-medical use, can realize its full potential while protecting its most valuable stakeholder: the consumer.

References:

1. . https://doi.org/10.1080/10826076.2021.1996390
2. Schwabe, Anna L., et al. "Uncomfortably high: Testing reveals inflated THC potency on retail Cannabis labels." PLoS One4 (2023): e0282396.
3. Zoorob, Michael J. "The frequency distribution of reported THC concentrations of legal cannabis flower products increases discontinuously around the 20% THC threshold in Nevada and Washington state." Journal of cannabis research3 (2021): 1-6.
4. Valdes-Donoso, Pablo, Daniel A. Sumner, and Robin Goldstein. "Costs of cannabis testing compliance: Assessing mandatory testing in the California cannabis market." PLoS one 15.4 (2020): e0232041.
5. Jikomes, N., and M. Zoorob. "The cannabinoid content of legal cannabis in Washington state varies systematically across testing facilities and popular consumer products. Sci Rep. 2018; 8 (1): 4519."