Did the Michigan Marijuana Regulatory Authority (MRA) ban molecular methods for microbial testing?

No, the MRA did not ban all qPCR tests for cannabis. In this article we aim to clarify some recent misinformation.

Updated April 16th, 2021

Did the Michigan Marijuana Regulatory Authority (MRA) ban qPCR?

  • No. In January of 2021, the MRA issued a statement  which temporarily "disallows the sole use of molecular methods such as qPCR for the quantification of total yeast and mold”, based on preliminary data from the AOAC’s Emergency Response Validation (ERV) to address the MRA’s concerns over TYM testing. However, the MRA said it will reevaluate this decision as new information is gleaned from the ERV study. Unfortunately the MRA’s decision to change the requirements based on an incomplete study and in "an abundance of caution" will likely cause significant disruption to the sector. 
  • We do not believe the MRA's January 2021 statement accurately reflects the status of molecular methods as per the AOAC ERV for Total Yeast and Mold (TYM). The study is ongoing and our PathoSEEK qPCR method is still being evaluated. Therefore, we feel it is inappropriate to rush to judgement until AOAC completes a comprehensive analysis of all methods. We remain committed to expediting our studies through the AOAC process and will inform our clients once AOAC provides official notice. 
  • The January 2021 statement provides guidance for how Michigan labs that currently use qPCR should test for TYM going forward.  
  • It should be noted that the AOAC's ERV aims to evaluate TYM methods on cannabis flower only. The MRA's statement does not specify a matrix in their temporary disallowment of molecular methods, but it appears that molecular methods for testing marijuana infused products (MIPS) have been temporarily disallowed as well. We believe this was an oversight by the MRA. 
  • Our other PathoSEEK® qPCR assays are not affected by this statement and are currently accepted by the MRA and are among the most widely adopted molecular assays used in cannabis safety testing in the US.

Does the MRA require labs to use AOAC certified methods?

  • No. The MRA does NOT require a method to be AOAC certified. There are only AOAC SMPR's established for a select few targets and in some cases, only for certain matrices (flower). 
  • Due to the confusion with their messaging in recent months, the MRA has published a letter to all licensed laboratories in Michigan on April 16th. In it they clarify the following:
    • All safety compliance facilities are required to employ the use of validated methods for all testing required by the agency in accordance with R 420.112(4)(b).
    • Additionally, R 420.305(2) requires a laboratory to use analytical testing methodologies for required safety tests to be validated by an independent third party, and are subject to monitoring on an ongoing basis. In the absence of reference to compendia or published methods, Appendix K (or J where appropriate) of the AOAC must be published in full.
    • When available, the standard method performance requirements (SMPRs) help to clarify the requirements of the validations. If the laboratory is running a method that has been appropriately validated or references a published method, the validation is expected to meet the targets (e.g. % recovery) outlined by the SMPRs. If the laboratory is seeking to pursue validation, either independently or with the assistance of a vendor, they must adhere to the published required analytical criteria.
    • Changes to the Technical Guidance document are issued twice a year, with the expectation of compliance to the requirements outlined in the guide within 6 months from the date of publication. Version 3.0 of the Sampling and Testing Technical Guidance for Marijuana Products was released on February 11, 2021. Therefore, safety compliance facilities must comply with the changes outlined in this guide on or before August 11, 2021.
    • All laboratories will receive updated method approval forms indicating any outstanding deficiencies. The laboratory is responsible for contacting their assigned LSS with any questions well in advance of the August 11, 2021 deadline for implementation of all changes.

What is MGC doing to address the situation with total count tests in Michigan?

  • Medicinal Genomics is a full participant in an AOAC Emergency Response Validation and our 3rd party produced validation data and matrix study results are still being evaluated. 
  • We have also notified the AOAC about problems with using Dichloran Rose Bengal with Chloramphenicol (DRBC) plates as the standard to evaluate other methods because Chloramphenicol inhibits the growth of dangerous fungi (Aspergillus, Penicillium, and Fusarium). The ERV study was at first designed with Potato Dextrose Agar as a reference culture media, but shortly after our initial data was submitted we were notified that the reference method was changed. We immediately duplicated our efforts comparing PathoSEEK® to DRBC and PDA. Our standard curve showed concordance with all culture medias.
  • We will publish our updated validation (per AOAC  Appendix J) of the Total Yeast and Mold Count method once complete and provide notice to our customers. 
  • Our new standalone TYM manufacturer method validation update and the inclusion/exclusion criteria provided within should suffice for any safety testing lab in Michigan to show the MRA they have sufficient evidence of a compliant method.

Are there any changes coming to the TYM or TC assay?

  • No. We are not making any changes to the primer design for our TYM qPCR assay. Inclusion and exclusion testing has confirmed that our primer design is solid.  
  • We are investigating improvements  to our extraction method so we can lyse open more cells, improve genomic DNA recovery, and improve concordance with plating when compared with industry CRMs.
  • These changes may result in a protocol update for the extraction step for the TYM assay, but no change to the assay design itself.

Does this mean my Total Yeast and Mold results have been wrong?

  • Any claims of contaminated samples in Michigan dispensaries are unsubstantiated and reckless.  There is an ongoing scientific debate amongst Michigan's cannabis testing laboratories and regulators over the different technologies used to detect yeasts and molds in cannabis (See the AOAC ERV Study). However, Michigan officials are on record as saying there is no public safety concern.
  • Our method validation for TYM is more robust than any on the market. The Cq/CFU equation in our validation document was generated with samples spiked with live organisms. Those organisms were chosen because they are well documented to be found on cannabis, or were well studied yeasts/molds,  and in most cases were used in 3Ms own method validation.

Are your Cq/CFU enumeration equations accurate?

  • Our extensive validation efforts show our development work on our Cq/CFU conversion equation. This has always been public and is also published in two peer reviewed papers and one non-reviewed white paper.
  • The issue that we believe precipitated the MRA's actions started with a new NSI CRM for TYM proficiency testing.  This PT was developed for culture based methods and does not produce qPCR results that are consistent with plating using MGC's SOP for total count tests.
    • Our own investigation found that the NSI CRM for TYM (the emerald test panel) was  ground to a fine powder, frozen, and contained cryopreservatives that are known to inhibit gDNA extraction.
  • In general, this is not surprising since plating for “total” counts are inherently flawed and not comparable to qPCR results. Not all yeasts and molds grow in culture plates, but are picked up in qPCR. Bacteria often grow in TYM  plates, but our assay is designed to exclude the bacteria. We write about this extensively in our help center: