Cannabis-Infused Edible Products in Colorado: Food Safety and Public Health Implications

Abstract

Cannabis-infused “edibles” are a popular means of cannabis use, and the variety of edible food products available to consumers continues to grow. Although there has been much discussion on dose standardization, childproof packaging, and the prevention of overconsumption, the important topic of food safety has received less attention.

We discuss potential food safety hazards associated with cannabis-infused edible food products, drawing on examples from Colorado, and describe edible-associated foodborne illness outbreaks and other contamination events.

It is important for public health agencies, particularly environmental health and enteric disease programs, to be familiar with the cannabis industry, including regulatory partners, signs and symptoms of cannabis ingestion, the scope of edible products sold and consumed, and the food safety risks unique to cannabis products.

On January 1, 2014, Colorado became the first state in the nation to allow sales of “recreational” (nonmedical) cannabis, having legalized medical cannabis in 2012. Medical cannabis is now legal in 30 states across the United States, with recreational cannabis legal in eight states.¹ Cannabis use has been linked to a broad set of health effects, including respiratory infections, vascular disease, mental illness, and motor vehicle injuries.² Therefore, in states where medical or recreational cannabis is now legal, many public health departments are monitoring the public health impact of cannabis legalization. Assessing the public health impact of increased cannabis use is further complicated by the new and evolving landscape of cannabis products available to consumers. Methods of cannabis use include smoking cannabis flower, vaping or “dabbing” with concentrated oils, topical application of lotions and salves, sublingual application of tinctures or drops, and ingesting cannabis-infused food products and beverages, referred to as “edibles.”^3,4

Edibles are a popular means of cannabis use.⁵ Edibles are especially popular among those who use cannabis for medical purposes and older adult cannabis users who value the discretion they offer in addition to perceived lower rates of toxin exposure and other health risks when compared with smoking cannabis flower.^3,6,7 In Colorado, as of November 2019, there were 289 state-licensed retail marijuana product manufacturers and 222 licensed medical marijuana–infused product manufacturers.⁸ There are currently no restrictions on types of edible products in Colorado. We reviewed available Web sites from a list of licensed manufacturers and retailers in Colorado to describe the range and frequency of products. The most frequently advertised products were candies (e.g., sour gummies, toffee) and beverages (e.g., sodas, juices), followed by baked goods and pastries; chocolates and cooking oils and sauces (e.g., olive oil, hot sauces); savory snacks (e.g., jerky); capsules and pills; sublingual drops, sprays, and oils; and syringes with oil to add to beverages.

In Colorado and elsewhere, public health and regulatory interventions on edibles have focused on dose standardization, childproof packaging, and the prevention of overconsumption. Less emphasis has been placed on the food safety risks associated with edibles or gaps in public health training or capacity to detect and investigate edible-associated public health incidents.^9,10 Without federal regulatory oversight, the responsibility for regulatory inspection and enforcement has fallen to state and local agencies. However, in Colorado, the Denver Department of Public Health and Environment (DDPHE) is the only agency that routinely inspects infused product manufacturers consistently with other types of food facilities. Additionally, there are limited guidelines for conducting surveillance for microbial contamination or unintentional consumption of cannabis-infused food products. Given the popularity of edibles, the growing variety of cannabis-infused edible food products available to consumers, and the lack of regulation and surveillance, food safety requires more focused attention.³ We discuss potential food safety hazards associated with cannabis-infused edible food products, drawing on examples from Colorado, and describe edible-associated public health investigations.

FOOD SAFETY HAZARDS

The production of any cannabis-infused edible food product includes cultivating the cannabis plant, processing plant material to extract concentrated oils, manufacturing the food, and infusing concentrated cannabis oil into the food. Each step in this process is subject to potential food safety hazards (Figure 1). Additionally, there are food safety risks associated with noncannabis ingredients.

FIGURE 1—

Cannabis Edibles Processing and Associated Hazards

Similar to other plants grown indoors, cannabis plants can potentially be exposed to a variety of food safety hazards, including contamination by metals, pesticides, molds, fungi, mites, and microbial pathogens, some of which are naturally occurring in the environment. Concentrated oils containing tetrahydrocannabinol (THC), cannabidiol, and other cannabinoids are extracted from raw plant material using solvents such as hydrocarbons and ethanol.³ Thus, concentrated cannabis oils may retain solvent impurities or residual solvents and could potentially contain concentrated amounts of contaminants; for example, a study in Oregon found detectable pesticides in 55% of cannabis concentrate samples (vs 29% of flower samples), with 46% failing Environmental Protection Agency tolerances.¹¹

Heat is required to decarboxylate tetrahydrocannabinolic acid (THCA) to its psychoactive form (i.e., THC), which can be done before food processing or during food processing, depending on the product. Cooking at an ambient temperature of approximately 220°F for 30 to 45 minutes is required to activate THC. Heating above the minimum THC temperature may cause some degradation to the THC, so producers may be incentivized to cook at lower temperatures, which may not meet minimum internal temperatures to kill microbial contaminants; for example, the US Department of Agriculture recommends that low-acid foods be heated to 240°F to 250°F to destroy Clostridium botulinum spores.¹²

In Colorado, food products are manufactured by licensed medical marijuana–infused product manufacturers or retail marijuana product manufacturers. Colorado’s cannabis rules prohibit manufacturers of edibles from using a commercially manufactured food product. The Colorado code and regulations for medical and retail marijuana edible production requires owners or licensees of manufacturing facilities to take a food safety course and to

comply with all kitchen-related health and safety standards of the relevant local jurisdiction and, to the extent applicable, with all Colorado Department of Public Health and Environmental Health (CDPHE) health and safety regulations applicable to retail food establishments.¹³

However, enforcement of these regulations is variable; for example, Denver is the only jurisdiction in Colorado that enforces food safety regulations with routine regulatory food safety inspections at all dispensaries and edible manufacturers every six months.

In Colorado, samples of edible products are collected internally by the manufacturer and test batches are sent to external laboratories for testing of potency, mycotoxins, total yeast and mold, residual solvents, metals, pesticides, Shiga toxin–producing Escherichia coli, and Salmonella.¹³ The testing of pathogens and residues remains a challenge, as does the development of extraction methods for the vast variety of edible products. To varying degrees, largely dependent on the state, limitations of laboratory testing persist, including nonstandardized protocols, inability to identify the source of a positive test (cannabis oil vs food ingredient), lack of access to testing, insufficient licensed laboratories to meet testing volume, inadequate methods for THC extraction from all potential edible food matrices, and testing accuracy not independently validated by state regulators.^14,15

Edibles are labeled, packaged, and delivered to medical or retail dispensaries, where they are sold to consumers. In Colorado, labeling requirements include the universal symbol, ingredient list, statement regarding refrigeration, statement of production date, statement of expiration date, nutrition facts panel, serving size, and total active THC statement. Storage at the production facility, retail store, or consumer’s home may affect the potency, quality, and safety of an edible product.^15,16 For example, improper ventilation can result in humid conditions and mold growth.¹⁶ Finally, there are potential hazards associated with individual use, including unintentional consumption, overconsumption, and off-label use.

Although some edible products are inherently lower risk because of their low-water activity, high acidity, or fermentation (e.g., baked goods), other products with low-acid and high-water activity (e.g., foods requiring refrigeration), as well as ready-to-eat foods, present a greater food safety risk. In addition, extractions used in edible products often have an oil, glycerol, or glycol base in which anaerobic pathogens, such as C. botulinum, can thrive if not prepared and stored properly.^17,18

The National Environmental Health Association developed guidance for cannabis food safety programs that summarizes regulations in states with legalized cannabis to address the hazards we have described. Food safety considerations include storage legislation for all production stages (e.g., cultivation, production, distribution, testing, and sale); standardized collection and testing methods at multiple production stages for potency, homogeneity, residual pesticides, cannabinoids, metals, microbials, mycotoxins, moisture content, and water activity; labeling and packaging regulations; training and education, including required food-handling certification; and food safety plans, including required hazard analysis critical control point plans, standard operating procedures, inspection requirements, and recall plans.¹⁶

EDIBLES-ASSOCIATED INVESTIGATIONS

An edibles-associated incident in Denver, Colorado, illustrates the food safety issues with cannabis products and considerations for cannabis public health investigations. In August 2014, shortly after Colorado legalized recreational cannabis, DDPHE investigated a cannabis-associated incident involving unintentional consumption of cannabis-infused chocolate at a pot pavilion at the Denver County Fair. Local and state officials were notified of 10 individuals experiencing apparent symptoms of acute cannabis intoxication after attending the pot pavilion. Investigators interviewed eight people, including two minors. Four adults sought medical treatment, and two were hospitalized overnight. Investigators found that all of the individuals had consumed a chocolate bar from the same vendor and that there was a dose response associated with the amount of chocolate consumed and symptom severity and duration. An environmental health investigation revealed that non-THC food samples were permitted at the pot pavilion for promotional purposes. Investigators found that non-THC chocolate bars were manufactured using the same processing equipment as THC-infused products and identified THC as the source of illness.¹⁹

As a result of this investigation, production of non-THC products in manufacturing facilities was prohibited, and, in 2015, Colorado passed a law requiring cannabis-infused foods to be imprinted with a universal symbol.

We searched the peer-reviewed gray literature and data on outbreaks reported to the National Outbreak Reporting System to identify other edible and enteric disease cannabis-associated public health investigations in the United States and internationally. We defined a public health investigation using the Centers for Disease Control and Prevention definition of a foodborne outbreak: “an incident in which two or more persons experience a similar illness resulting from the ingestion of a common food” (http://bit.ly/2Vpb2TR). Using this definition, we included incidents associated with microbial contamination of a cannabis product resulting in gastrointestinal illness, as well as unintentional consumption or overconsumption of THC in food resulting in common symptoms.

Including the Colorado pot pavilion investigation, we identified 13 edibles-associated public health investigations between 1978 and January 2018, all of which were related to overconsumption of THC. Only three occurred before 1996, when California first legalized medical cannabis. The number of cases ranged from three to 21 (mean = nine cases; Table 1). Hospitalizations were reported in six investigations. Individuals reported a range of gastrointestinal, psychological, and cardiovascular symptoms. Illness severity varied by age, with children experiencing more severe illness, which is consistent with other literature on acute cannabis intoxication.²¹

TABLE 1—

Edibles-Associated Public Health Investigations

Year	Source of Illness	Food Vehicle	Location	Setting	Cases, No.	Signs/Symptoms	Source
2018	THC	Gummy candies	NM	Elementary school	6	Dizziness, gastrointestinal	20
2016	THC	Cookies	Slovenia	Workshop	12	Vomiting, drowsiness, reduced level of consciousness (one coma), dizzy, hallucinations, mild hypothermia, elevated blood glucose levels, hypokalemia	21
2016	THC	Gummy bears	IL	College campus	12	NA	22
2016	THC	Gummy candies	CA	Child’s birthday party	21	Dizziness, tachycardia, hypertension, tachypnea, abnormal visual symptoms, lethargy	23
2014	THC	Brownies	CA	High school	5	Nausea, vomiting, loss of consciousness	24
2014	THC	Chocolate bar	CO	Fair festival	10	Nausea, vomiting, disorientation, dizziness, anxiety, hallucinations, stomachache, dry mouth, numbness/tingling in extremities, confusion, dyspnea, sweating, fainting, chest tightness, loss of coordination, panic, paranoia, difficulty speaking, memory loss	19
2011	THC	Cheesecake	CA	Restaurant		NA	25
2009	THC	Brownies	CA	Preschool teacher’s breakroom	6	Agitation, altered mood, altered taste, anxiety, ataxia, burning eyes, chills, dizziness, drowsiness, dry mouth/throat, excessive sweating, fatigue, giddiness, headache, increased appetite, itching, itching eyes, loss of appetite, mouth irritation, muscle twitching, nausea, numbness, palpitations, shortness of breath, tingling, vomiting, weakness	26
2008	THC	Brownies	OH	College campus	3	NA	22
2006	THC	Cookies	OR	Office/indoor workplace	15	NA	22
1995	THC	Salad	Switzerland		4	Tachycardia, blood pressure changes, nausea, vomiting, paresthesia, ataxia, muscle weakness, cough, euphoria, dysphoria, sleepiness,	27
1981	THC	Zucchini cake	CA	College campus	9	Dry mouth, dizziness, tachycardia, blurred vision, memory lapse, tingling, anxiety, confusion and drowsiness, nausea, headache	28
1978	THC	Bundt cake	CO	Office	9	Muscular incoordination, dizziness, difficulty concentrating, confusion, difficulty walking, dysarthria, dry mouth, dysphagia, blurred vision, vomiting	29

Note. NA = not available; THC = tetrahydrocannabinol.

Eight investigations were associated with baked goods (brownies, cakes), four with candies or chocolates (chocolate bar, gummy candies), and one with a salad prepared with hemp seed oil. The onset and duration of illness was highly variable. The average onset with orally ingested cannabis is approximately 30 to 120 minutes, and the duration is up to 12 hours, although it can be longer and depends on numerous factors, such as past use, health status, age, weight, metabolism, gender, food intake, and other factors.^3,30 In addition to edibles-associated investigations, we identified one multistate investigation in Ohio and Michigan associated with microbial contamination of Salmonella muenchen in cannabis flower.³¹

Recalls, consumer advisories, and other media reports of potentially hazardous cannabis products identified from routine inspections have also been reported. DDPHE Cannabis Consumer Protection has posted 45 voluntary recall notices and consumer advisories on their Web site (Denvergov.org) for cannabis products, including flower, concentrates, and edibles. Cited hazards included the presence of pesticide residues (36 recalls), the presence of yeast or mold (six recalls), non–food grade ingredients (essential oils, two recalls), powdery mildew and mite contamination (one recall), temperature controls (one advisory), and improper storage (one advisory). Eight identified specific edibles products, including beverages, mints, chocolate bars, baked goods, candies, olive oil, and baking mixes (Appendix A, available as a supplement to the online version of this article at http://www.ajph.org). These recalls highlight the importance of routine inspections in facilities producing cannabis-infused products and the importance of identifying public health authority to recall products.

THE FUTURE OF FOOD SAFETY AND CANNABIS

As the edible industry expands, it is important for epidemiologists and environmental health professionals to understand the prevalence of edible cannabis use, symptoms associated with cannabis intoxication, and foodborne illness risks associated with edible production. The US Drug Enforcement Agency continues to categorize cannabis as a Schedule 1 drug, restricting the use of funds for regulating the industry. For states, this means that the responsibility for the regulation of cannabis, including the safety of edibles, falls to state and local jurisdictions, and many environmental health agencies do not routinely inspect and regulate edibles manufacturers as food facilities. In an edible-associated investigation, public health partners may participate in or lead an investigation. As of 2018, emergency treatment, hospitalization, and death related to exposure of cannabis products are reportable conditions in Colorado. The surveillance of edibles-associated illnesses involves public health and other partners, including the National Poison Data System, highlighting the importance of interagency collaboration and communication.

As our review demonstrates, cannabis-associated investigations have most often occurred in incidences related to unintentional ingestion of a cannabis product. Although only one investigation was associated with a microbiological pathogen, hepatitis A and aspergillosis have previously been associated with users of smoked cannabis.^32,33 Reported incidents appear to be increasing with legalization and present novel challenges to investigators, including nongastrointestinal symptoms, and new partners (e.g., law enforcement). It is increasingly important that we have the capacity to do surveillance to detect these incidents, as they are likely underreported. Recalls, consumer advisories, and other media reports of potentially hazardous cannabis edible products identified in routine inspections have also been reported. This highlights the importance of routine inspections in facilities producing cannabis-infused products and the importance of identifying the public health authority to recall products.

In anticipation of potential public health events, public and environmental health agencies have taken steps to respond to cannabis-related incidents. For example, CDPHE has developed a guidance document for local public health agencies on handling suspected outbreaks or complaints of enteric illness associated with cannabis edibles.³⁴ CDPHE is conducting surveillance in coordination with emergency departments, the Rocky Mountain Poison and Drug Center, and local health agencies.³⁵ CDPHE has added questions about edibles to routine enteric disease questionnaires and created a supplemental outbreak questionnaire.^9,35 The Colorado Integrated Food Safety Center of Excellence has developed educational materials for public health professionals, including a tabletop exercise to educate enteric disease investigators on cannabis and how to prepare for a cannabis-related outbreak investigation.³⁶ DDPHE has developed sanitation guidance for the cannabis industry and an inspection checklist to prepare cannabis operators for regulatory inspections.³⁷ Finally, the National Environmental Health Association has its “Cannabis 101 Glossary,” the document “Food Safety Guidance for Cannabis-Infused Products,” and a cannabis webinar series.¹⁶

In summary, edibles present a number of public health concerns and will continue to challenge public health professionals as their popularity increases. There are currently no comprehensive food safety recommendations and regulations for cannabis-infused products. It is important for public health agencies, particularly environmental health and enteric disease programs, to be familiar with the cannabis industry, including regulatory partners, signs and symptoms of cannabis ingestion, the scope of edible products sold and consumed, and the food safety risks unique to cannabis products. In addition to the preparation and education of public health professionals, research is needed to determine food safety interventions (e.g., hazard analysis critical control point plans) that will prevent cannabis-associated illness. Researchers should also investigate public health risks associated with consuming cannabis and how consumption patterns and risks differ by populations known to be at higher risk for complications associated with enteric illnesses.