Adapting to Change: Heavy Metals Testing

Adapting to Change: Heavy Metals Testing

You’re already aware of the regulation change — as of this month, all cannabis in Oregon is required to pass heavy metals testing. The complete rules under the Public Health Division can be found here, and as stipulated in OAR 333-007-0415, the heavy metals standards and action limits are as follows (ug/g = micrograms per gram):

• Arsenic — 0.2 ug/g
• Cadmium — 0.2 ug/g
• Lead — 0.5 ug/g
• Mercury — 0.1 ug/g

This change is a big deal for everyone from farms and producers to labs, dispensaries, and consumers. The good thing is that it continues the progress of safe and responsible production, sale, and consumption of cannabis. And the heavy metals of concern align with standards in other states. The challenge is that some products will not be ready to pass the new tests, and in many cases there will be a lot of hard work and continued education to get the industry up to speed.

In this post, we’ll expose what’s happening inside the lab to make heavy metals testing possible at Pree, we’ll share findings from our early tests, and we’ll get into some of the implications for farms and producers.

Expanding our testing capabilities

We empathize with the effort required for producers, because we had our work cut out for us in the lab. For starters, we needed more room. Getting that space set up meant bringing in additional power and another source of water. In addition to the new lab instrument, we needed the gasses used with it, a fume hood, and an emergency shower to keep our team safe. Then we had a round of approval from the OLCC before even beginning our method making process.

With that green light, we could start our method validation, which is a three-day process that ballooned to two weeks due to lead in our water (which is common, but also one of the heavy metals we’re testing for!). Now the water used with the instrument passes through a deionization water filtration system to ensure there is no contamination in testing.

Then we were able to dial in our protocol and lab procedures to make sure our people are safe and our test results are sound. Every sample is tested blindly to prevent any kind of bias — we weigh out 500mg, go through acid additions and water before entering the microwave (digestor), run it on the ICP-MS and return the results. We’ve passed all of our proficiency testing, so we’re confident with the new process. And our early results have been telling for what’s to come…

What we’re finding so far

We’ve worked closely with a number of farms over the last several months to be a step ahead of the new requirements. That has included examining upstream from the flower to the grow conditions, specifically the soil, fertilizer, and water. The short version is that we’re seeing some failures, as well as quite a few “passing hits” (presence of heavy metal, but below the action limit).

The primary impact is in the soil, especially with various organic blends and higher-end mixes – what’s coming up the most is arsenic, followed by some cadmium and lead. We’re trying to identify the source of the arsenic issue, and there could be a link to soil amendments like worm castings or liquid fertilizer, which we’ll investigate further. We’re not seeing as much of an issue with water testing, likely due to many already testing their own water.

For added context, it’s worth mentioning that the action limits for cannabis are particularly stringent. One study found an average of .86 micrograms of Cadmium per gram of tobacco in cigarettes, among notable levels of other heavy metals, and concluded, “because of the variety of toxic heavy metals in cigarette tobacco, and their numerous negative health effects, metal content in cigarette tobacco should be reduced.”

We’ve tested tobacco products ourselves and found that they fail the pesticide tests our local cannabis products are required to pass. We’ve even thrown foods like chocolate or canned tuna into our equipment and revealed failing levels of heavy metals by cannabis standards. While it may be tough criteria for a new test, the good thing is that all of this means we’re making cannabis safer.

Implications for farms

Here are some important takeaways we’ve learned up to this point:

1. Regional native soil — Heavy metals aren’t just a result of human processes and products; they’re naturally occurring in the earth. What lies in the dirt under your feet depends on where you are in the state, as evidenced by our test results from different regions.
2. Organic vs hydroponic — We’re not here to pick sides between these methodologies, but the simple truth is that hydroponic grow systems use less soil, and since soil has been the primary culprit for heavy metals, hydroponic operations may be more likely to pass.
3. Supplier standards — Many essential agricultural materials are coming from massive national suppliers, and their standards for mass production may not be the same as what your business or our state expect from cannabis. Farms will need to get hyper-focused about each element of their supply chain to better understand their inputs and outputs.
4. Remediation — If your harvested flower fails a pesticide test, you still have the option of degrading the presence of pesticides with UV light and then retesting. Unfortunately the same is not true for heavy metals; they cannot be degraded.
5. Plan ahead — It could take months to identify and correct an issue in your production process. Once the flower is harvested, it’s likely already too late — be thinking upstream about your clones and grow conditions to get the most out of your next harvest.