Marijuana & Microbes: Safely Using a Carbon-Dioxide Incubator in Testing

State requirements for cannabis are not uniform, however, microbial testing remains generally universal. Checking cannabis for microorganisms makes sense from producing the plants to preparing products. Those processes could require various lab devices, including a carbon-dioxide (CO₂) incubator. Beyond getting the most research benefits from such an incubator, it needs to be used safely.

A team of researchers from the U.S. Center for Disease Control and Prevention (CDC) and the National Institute for Occupational Safety and Health (NIOSH) showed that workers in a cannabis field can be exposed to various levels of bacteria and fungi. This research team noted: “The results of this pilot study suggest that the cannabis farmworkers are potentially exposed to Actinobacteria as well as the cannabis plant pathogen, B. cinerea during harvesting, bud-stripping, and hand-trimming processes.”

NIOSH scientists described various potential health hazards when working with cannabis. In cannabis-growing operations, for example, the scientists found more than 200 kinds of fungus, including some of the ones noted in the CDC-NIOSH study. The researchers added that “breathing zone air samples were predominantly composed of Botrytis cinerea, a cannabis plant pathogen. B. cinerea, commonly known as gray mold within the industry, has been previously associated with hypersensitivity pneumonitis.”

The microbes in the field or in any processing step can also end up in products, which drives the need for microbial testing.

CO₂-Safety Basics

One of the most common methods of assessing microbes in cannabis or cannabis-based products involves culture-based testing. Here a sample is placed in a known medium and cultured to see what microbes grow and how many. When needed, a CO₂ incubator can be used to replicate a cell’s natural environment by maintaining the desired pH, temperature and relative humidity. For an overview on incubator operation, see NuAire’s white paper: CO₂ Incubator: Proper Use and Preventative Maintenance.

“CO₂ incubators have myriad applications in the laboratory and are relatively safe especially when Good Laboratory Practices—GLPs—are followed,” says Christian Sweeney, vice president of science & technology at Cannabistry. “One of the main hazards to be aware of would be the storage and transport of carbon-dioxide gas on-site, which could result in heightened CO₂ exposure in the event of a leak.”

To reduce the odds of CO₂-related hazards, Sweeney made several suggestions. “This risk is easily mitigated in two ways,” he said. “First, ensure proper validation of your incubator by three common qualifications: installation qualification, IQ; operational qualification, OQ; and performance qualification, PQ.” As a second suggestion, he said, “Ensure the presence of a CO₂ detector—either fixed in place in the areas containing carbon dioxide, or a personal CO₂ alarm that monitors exposure to an individual.”

Cannabis must be tested for microorganisms to ensure the safety of growers and customers. Lab personnel also require protection during the microbial-testing workflow. If that protection involves a CO₂ incubator, a lab manager must ensure that the device is used as designed and is properly maintained. Here, a little effort and care go a long way in keeping everyone in the cannabis supply chain and customers safe from microbial contamination.