Pathogens in Hemp: Why is Aspergillus a concern?

Aspergillus and hemp…why the concern?

J. David Legan, PhD – Associate Dir of Research – Eurofins Microbiology Laboratories

While many states only have regulations in place for tetrahydrocannabinol (THC), other states are looking at the overall safety of hemp industry products and are establishing regulations for pesticides, residual solvents, and microbiological organisms. This means that regulations are inconsistent from state to state. For example, both Colorado and California require testing of cannabidiol (CBD) for microbiological contamination. Since the regulations set by each state differ, each state has varying requirements for microbiological testing. To the extent that testing requirements exist, they seem to have originally been created around their medical marijuana programs. Nevertheless, some users consume medical marijuana in an ingestible form, so California regulations also address testing for common food-poisoning organisms, including Salmonella and Shiga-toxin producing Escherichia coli (STEC), which may not be present in 1 g of product . Detecting these organisms is a common task in any food microbiology laboratory. However, California also requires laboratories to test for the pathogenic Aspergillus mold species (A. fumigatus, A. flavus, A. niger, and A. terreus) in all medical cannabis goods intended for consumption by inhalation, including but not limited to dried flower, kief, hashish, oil, and wax products.

Why should states be concerned about these microorganisms?

All microorganisms that can cause lung infections should not be present in any hemp material which is to be deliberately inhaled. Aspergillus fumigatus can cause serious lung infections, particularly in immunocompromised persons. Aspergillus flavus is the next most important cause of lung infections and can produce a toxin (alatoxin) known to cause cancer in a wide range of mammalian and avian species. Aspergillus niger may occasionally cause lung infections and, at an incidence that is increasing faster than the incidence of other Aspergillus infections, Aspergillus terreus can opportunistically cause lung infections in people and is considered an emerging pathogen.

None of the molds noted above are relevant in hemp products that will be consumed by ingestion, but residual aflatoxin created by previous growth of A. flavus still would be a concern. Illinois regulations require testing for aflatoxin and common bacterial pathogens but do not explicitly call for testing for pathogenic Aspergillus species. Does this indicate that Illinois consumers have shown a preference for ingestible rather than inhalable forms? We have no information on this, and it simply might be another indicator about the confusion in the current patchwork of regulations.

A detailed whitepaper (May 2015) on risks and recommended testing of cannabis products can be found here and 2016 guidance from the American Public Health Association can be found here. A somewhat dated summary of state regulations updated in August 2017 is available here. There is no doubt that this is an area where things will change rapidly with the increase in production and use of hemp and CBD.