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

Alice E. White, MS; Christine Van Tubbergen, MPH; Brianna Raymes, MPH; Alexandra Elyse Contreras, MPH; Elaine J. Scallan Walter, PhD


Am J Public Health. 2020;110(6):790-795. 

In This Article

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" ( 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]

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 ( 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 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.