Microbial Testing in Cannabis: Regulatory and Analytical Challenges

September 24, 2018
Table I: APHL regulatory guidelines
Table I: APHL regulatory guidelines
Abstract / Synopsis: 

Cannabis testing regulations are constantly evolving with the industry as it grows and gains acceptance. Currently, microbial contaminant testing regulations vary on a state-by-state basis and sometimes are lacking or inconsistent. As a result of the variability and continuous and sometimes hasty changes, the testing of cannabis product for microbial contamination faces constant and evolving challenges. Of the many current challenges facing regulators and laboratories regarding both testing and product safety, the most glaring are varying sample sizes, impossibly short testing deadlines, enumerable product types released to the market, a lack of standardized industry testing conventions, and incongruities in testing requirements. These challenges amount to a sizable regulatory and testing gap in the industry; a gap in which cannabis is tested for contaminants, but the collected data can sometimes lack statistical validity or mislead to assumptions of product safety. Despite these difficulties, numerous industries outside of cannabis have faced and solved similar problems and can offer solutions directly applicable to the cannabis industry. This article outlines some of the current major challenges for both regulators and laboratories regarding the microbial testing of cannabis products. The article is further intended to provide information and resources to aid laboratories and regulators in the eventual resolution of the highlighted difficulties.

Microbial testing in cannabis has become standard practice and a requirement across most states with legal markets. Although the regulations vary from state to state, the general challenges facing microbiologists are more consistent. Rapid regulatory changes and a lack of general consensus on methods seem to be the only true constants. In general, states usually require an array of tests, including total yeast and mold or select mold species identification, Salmonella (<1 colony forming unit [CFU]/g), toxigenic E. coli (<1 CFU/g), total aerobic plate count, total enteric count, as well as other specific bacterial contaminants. But very seldom do state regulations exactly match one another. New York, for example, requires a vast array of testing not seen in other legal states (Clostridium spp., Streptococcus spp., Penicillium spp, Aspergillus spp, and Mucor spp), while Colorado requires only three microbial tests (3,15). These inconsistencies as well as industry lobbying have led to skepticism regarding microbial testing as a legitimate need in the cannabis industry. However, depending on the product type and the end consumer for which the product is destined, microbial testing is absolutely necessary; but it is a valid concern that testing requirements are simply applied to all matrix types regardless of the intended use or consumer.

To add to the complexity, methodologies adopted in various microbial testing categories vary tremendously and include older, tried and true compendial methods adopted from other industries (or variations of compendial methods) that are run alongside innovative new methods which are less heavily vetted. New methods generally are faster and have better sensitivity, but often are not nearly as well tested in application. Although the challenges seem daunting, it is important to keep in mind that every fledgling industry has faced similar challenges and, while cannabis can, at times, appear as though it is completely new, it does have striking similarities to both the food and environmental industries.

Challenges to the Legitimacy of Microbial Testing

“Is microbial testing really necessary?” That’s a question often raised in Colorado.

At first glance, the answer should be a resounding “yes!” but legitimate concerns are being raised about what is being tested for and why. However, a far less valid argument, but one still faced by microbiologists and regulators, is the question: “why test if no one has gotten sick from . . . Salmonella, E. coli, and so on?” While it might be true that contamination of certain products by say, E. coli or Salmonella might be unlikely, “what if’s” must always play a role when analyzing the risks involved with product manufacture and distribution. The cannabis industry is young, and historical outbreak data is extremely limited, but the problems faced by other manufacturing industries are directly similar and it is never acceptable to base testing solely upon what has happened in the past (12). To address the issue of determining appropriate target contaminants in cannabis products, a few basic questions should be considered (12):

  • Who is the product destined for?
  • What is the likelihood of contamination in the product?
  • What impact would there be if the product was contaminated?
  • Are there process controls or steps in manufacturing during which contamination is likely controlled?

Although these questions seem like the logical place to start, regulators often are challenged with getting rules into place quickly, typically only months before a product is allowed to be offered for sale. Thus, rules may be drafted and implemented based on worst case scenario only. In fact, draft regulations have even listed criteria for marijuana bud as strict as <1 CFU/g of bile-tolerant Gram-negative bacteria as well as <1 CFU/g for total mold, which would have mandated a product impossible to produce. Current regulations across the country are generally strict and some are arguably overbearing. At the same time, it is almost always better to err on the side of caution and if a product could be destined for immunocompromised individuals (the very old, sick, or very young), then strict testing requirements are indeed necessary (5,12). To aid regulators in promulgating rules that have precedent, the Association of Public Health Laboratories put out an excellent guide outlining potential contaminates in various cannabis product (see Table I) (2). (See upper right for Table I, click to enlarge. Table I: APHL regulatory guidelines.)

  1. Association of Analytical Communities (AOAC), “Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces,” http://www.aoac.org/imis15_prod/AOAC_Docs/StandardsDevelopment/AOAC_ Validation_Guidelines_for_Food_Microbiology-Prepub_version.pdf (2012).
  2. Association of Public Health Laboratories (APHL), “Guidance for State Medical Cannabis Testing Programs,” https://www.aphl.org/aboutAPHL/publications/Documents/EH-Guide-State-Med-Cannabis-052016.pdf (2016).
  3. “Colorado Retail Marijuana Code,” Adpoted Rules, CCR 1 212-2, Rule 712, Section R 712 – Retail Marijuana Testing Facilities: Sampling and Testig Program, E. Permissable Levels of Contaminats (Adpoted November 17, 2017; Effective January 1, 2018), pp. 124–125.
  4. US Food and Drug Administration, (FDA), Bacteriological Analytical Manual (BAM)https://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm (FDA, Rockville, Maryland, 2016).
  5. US Food and Drug Administration, Office of Foods and Veterinary Medicine, Guidelines for the Validation of Analytical Methods for the Detection of Microbial Pathogens in Foods and Feeds 2nd Edition, http://www.fda.gov/downloads/ScienceResearch/FieldScience/UCM298730.pdf (FDA, Rockville, Maryland, 2015).
  6. US Food and Drug Administration, Office of Regulatory Affairs: Inspections, Compliance, Enforcement, and Criminal Investigations, Investigations Operations Manual, Chapter 4 - Sampling, https://www.fda.gov/downloads/ICECI/Inspections/IOM/UCM123507.pdf (FDA, Rockville, Maryland, 2018).
  7. International Standards Organization ISO 22119 Microbiology of food and animal feed stuff – Real-time polymerase chain reaction (PCR) for the detection of food borne pathogens – General requirements and definitions, https://www.iso.org/standard/45035.html (ISO, 2011).
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  12. S. Mortimore and C. Wallace, HACCP: A Practical Approach, 3rd Ed. (Springer, Springer New York, 2013).
  13. P. Bird, J. Flannery, E. Crowley, J. Agin, and D. Goins, J. AOAC Int. 98(3), 1563–1575 (2015).
  14. R.A. Cowie, Quality Assurance for Microbiology in Feed Analysis Laboratories, (Food and Agriculture Organization of the United Nations, Rome, 2013).
  15. Rules and Regulations of the State of New York, § 55-2.15 Requirements for laboratories performing testing for medical marihuana (Regulatory Amendments, Effective December 27, 2017), 1004.13 (g) 32-33.
  16. Y. Salfinger and M.L. Tortorello, Compendium of Methods for the Microbiological Examination of Foods, 5th Edition (American Public Health Association, 2015).
  17. S. Dahms, ”Microbiological Sampling Plans – Statistical Aspects” presented at the 36th Symposium of the Swiss Society of Food Hygiene, Zurich, Germany (2003), pp. 33–36.
  18. S. Sutton, Journal of Validation Technologies 17(3), 42–46 (2011).
  19. V.H. Tournas, L. Feliciano, and E.J. Katsoudas, J. Food Saf. 30, 506-514 (2010).

Matthew A. Ward is the Marijuana Laboratory Auditor with the Colorado Laboratory Services Division, Department of Public Health & Environment in Denver, Colorado. Direct correspondence to: [email protected]

How to Cite This Article

M.A. Ward, Cannabis Science and Technology 1(3), 22-28 (2018).