Inside ASTM D8575-25: The First Standard Guide For Cannabis Microbial Control

Inside ASTM D8575-25: The First Standard Guide For Cannabis Microbial Control

ASTM International published D8575-25 in May 2025, the first standard guide for microbial control in post-harvest cannabis and hemp. It was written for cultivators, regulatory agencies, and consumers. Ziel’s VP of Scientific and Regulatory Affairs, Parastoo Yaghmaee, was one of the experts who helped with writing it, and supplied the Radio Frequency portion.

It will not tell you which technique to buy.

We say that first because it is the part operators misread, and because Ziel has been on the answering end of that question since a large Colorado operator called about state microbial testing a decade ago. The guide describes. It does not endorse.

What A Guide Is, And What It Will Not Do

D8575-25 is a guide, and ASTM guides are exactly that. They exist to provide neutral information, so the reader can make an informed decision that is safe for business and consumers, and they define and explain the options available rather than endorsing any one of them. ASTM also publishes specifications, classifications, and test methods, and knowing which of those you are holding decides how much weight it carries once it reaches your Standard Operating Procedures. What D8575-25 features is an ongoing list of techniques that may be used to decontaminate post-harvest cannabis to meet regulatory compliance.

The American Society for Testing and Materials has produced voluntary standard guides for over 100 years, across industries ranging from railroads and steel to soil and water, with offices located across the globe. The organization is not-for-profit and nongovernmental. None of it binds anyone on its own, and the guides are not meant to endorse any one technology, practice, or approach over another. What changed is that the options for post-harvest cannabis finally sit described in one agreed place.

In May of 2025, the guide was officially released to the public. It can be found for purchase here.

Four Years In The Room

The Cannabis Committee, D37, came first. Parastoo joined ASTM International in 2020 on behalf of Ziel, after D37 was established, and over the following years she and other cannabis industry experts worked through the question of microbial standards. In 2021 they formed a subcommittee to develop the first industry standard guide for cannabis, focused on decontamination technologies already established in the food industry. Some of those, Radio Frequency among them, already had a presence in cannabis.

The writing was split by technology, each expert taking the method they knew best. Parastoo’s portion covered how RF works and why it remediates cannabis without damaging the plant or its chemicals, which is the ground Ziel has worked in since before cannabis was the application. Every author brought a section back to the full subcommittee for review.

Then the slow part. Approval requires consensus from all members, so the draft moved from the subcommittee to the main cannabis committee, absorbed a few rounds of edits and updates, and went to the entire ASTM International organization for review and sign off only once both bodies had agreed. A few years of in-depth research and review, start to finish, before it reached the public.

The Techniques The Guide Describes

The guide details ionizing radiation, meaning gamma and e-beam, along with ozone, UV, and non-ionizing Radio Frequency. Steam pasteurization and other less common options are in there too. Each one is described neutrally, which is what a guide does, and it also means the comparison work is yours. Two questions carry most of that work: how far the energy reaches into a bud, and what it leaves behind.

Gamma sends high-energy photons deep into the flower and disrupts mold and pathogen DNA, though some evidence shows that enough DNA is left intact for those microbes to revive themselves afterward.

E-beam uses high-energy electrons that penetrate the flower, though not as deeply as gamma, so there is no guarantee it eliminates pathogens sitting in the core of the bud. X-ray, which the guide does not name but which comes up in the same conversation constantly, falls between the two on penetration depth and energy and leaves the same open question about the core.

Radio Frequency works from the other direction. Long, lower-energy waves envelop the flower in an electromagnetic field, reach the core of the bud, and treat it from the inside out.

That split between the two families is physical, not promotional. Ionizing radiation removes electrons from the atoms of the flower, essentially nullifying its natural integrity, and sterilizes the product by killing the plant’s natural enzymatic properties, which affects natural aroma. Non-ionizing RF is a thermal process instead. The oscillating field syncs the flower’s moisture molecules and sets them rotating in unison, turning 27 million times per second, and the friction builds enough heat to kill microbial pathogens but never enough to degrade or decarboxylate THC. In the Ziel RFX, a Siemens PLC/HMI system monitors that heat in real time through temperature probes, which is how potency, terpene profile, and sensory qualities come through the run intact.

Where The Guide Stops And Your SOP Starts

A list of techniques is not a decision.

Operating without a decontamination strategy in your Standard Operating Procedures can cost thousands to millions of dollars in revenue on harvests that fail to meet regulatory requirements. With the right remediation strategy, those harvests can be saved and sold as whole flower instead of being downgraded to concentrate products, which tend to have lower market value. Incorporating a microbial control solution into your SOPs is the only way to pass cannabis compliance with consistency.

D8575-25 will not tell you which method suits your starting microbial counts, your throughput, or your export plans. That part starts with your own Certificates of Analysis, and it is the only part of this that nobody else can do for you.

Reading The Guide Against Your Own COAs

The panel you get screened against depends on where you operate. Common criteria include Total Yeast and Mold Count (TYMC), Total Aerobic Microbial Count (TAMC), Aspergillus, coliforms, E. coli, and bile-tolerant gram-negative bacteria (BTGN).

Labs get there two ways. Culture-based testing plates a sample on selective media, incubates it under specific conditions to allow targeted microbes to grow, and counts the colonies, expressed as colony-forming units per gram. The PCR method detects and quantifies the microbial DNA of specific pathogens instead.

Log reduction is what connects a treatment to a passing result. Every log is a tenfold change, so a log reduction of 3 leaves one thousandth of the starting count, which is a 99.9% reduction. As a rule of thumb, each additional log adds a 9. A log reduction of 6 is 99.9999%. Labs count CFU/g before treatment, then count the same pathogen again on a sample sent after treatment, and the difference between the two is your log reduction. Radio Frequency is proven to reduce TYMC by more than 99.9%, and it also addresses TAMC, BTGN, coliforms, and Aspergillus. In limited production runs on flower that tested positive for Aspergillus, Radio Frequency brought that product to compliance.

The Export Consequence Most Operators Read Last

Picking a method has consequences past the state lab.

Radio Frequency has been used in other agricultural industries for decades and has already been approved for organic operations by the National Organic Program and the USDA. It is also, by Ziel’s reading, the only microbial control solution that carries no additional licensing or labeling requirement for cannabis exported to European and Canadian markets. Ziel is certified in Canada as compliant with organic processes in cannabis. Radio frequency is suitable for organic and GMP-certified operations.

If you have export ambitions, that shifts the math on which technique goes into the SOP. The guide will not make that call.

Frequently Asked Questions

Is ASTM D8575-25 Mandatory?

Voluntary. Every ASTM standard is, and this one is a guide on top of that, so there is nothing in it for anyone to enforce. Regulatory agencies sit in the intended audience because a neutral description of the techniques their licensees run is useful to them, which is a different job from setting a limit. Your compliance obligations still come from your state or, north of the border, from Canadian regulations.

Where Can I Buy ASTM D8575-25?

Through the ASTM store listing for D8575-25, where it is shown as an active standard.

What Does Post-Harvest Inflorescence Mean?

Dried flower. It is the phrase in the standard’s title, and it is worth knowing before you buy a copy expecting coverage of everything that leaves your facility. Check the scope clause in the standard itself for what sits inside and outside it.

Do Cultivators Need To Identify The Mold Species First?

You don’t need to identify the type of mold before treatment. Whether the standard has anything to say about species identification is a question for the copy on your desk, not for us.

What Is A Gram Stain Test?

A test used to identify bacteria. The sample is stained and examined under a microscope, and the bacteria are classified by the color they turn: purple for Gram-positive, pink for Gram-negative. That classification sits behind the middle two letters of BTGN.

Is A Microbial Kill Step Standard Outside Cannabis?

Any business that grows or manufactures products for human consumption runs Standard Operating Procedures built around quality and consumer safety, and in the food industry a microbial kill step is a standard part of that. Milk is the example everyone already knows. Pasteurization is not an emergency measure applied to bad batches. It is a step written into the process from the start, and Ziel’s roots are in food safety, which is where we learned to think about cannabis the same way, as a process to control rather than a fire to put out.

How Does D8575-25 Help A Facility Writing Its First Post-Harvest SOP?

Picture a cultivator whose last three harvests came back over the TYMC limit, sitting with a lab report and no kill step in the SOP. The guide does not solve that. What it does is hand everyone in the room the same vocabulary and the same neutral description of each option, so when the operations lead, the compliance officer, and two equipment vendors sit down, they are working from one definition of what gamma, e-beam, ozone, UV, and Radio Frequency each do to a bud. That shortens the argument. It also keeps the conversation on penetration depth, throughput, and labeling consequences instead of on marketing claims.

Putting D8575-25 To Work Before Your Next Harvest

Pull your last four COAs and find the criterion that keeps landing closest to the limit. For most operators, that is TYMC. That number tells you the log reduction you need, and the log reduction narrows which of the techniques in the guide are genuinely in play for your operation.

Ziel does not sell equipment. We sell solutions, built around each customer’s starting COAs and their business goals, whether the problem is high starting microbial counts or throughput that will not keep pace with harvest. Bring your COAs to the Ziel team and we will tell you where Radio Frequency fits in your SOP.