By: Matthew Ellis, President, ExtractionTek Solutions
Setting the record straight on the safety of hydrocarbon extracted cannabis concentrates
I’ve heard it so many times. “Aren’t hydrocarbon extractions bad because they have, like, butane in them? I don’t want butane in my concentrates. It’s flammable!”
The short answer is that hydrocarbons aren’t significantly present in hydrocarbon derived products. There are more hydrocarbon molecules in the air you’ll breathe today than you’ll get in your next dab session.
Lots of food grade and pharmaceutical processes utilize hydrocarbon extraction. In my eight years of experience in the extraction industry, I’ve used hydrocarbons to extract compounds from cannabis and hemp for sure, but also hot chili peppers and lobster shells, strangely enough. Hydrocarbon extraction is a versatile and long-standing technique employed for coffee decaffeination, botanical oil production and most products containing mint flavoring. We’ve all been safely consuming hydrocarbon extracted products for a long time without even knowing it.
It’s true. There’s far less butane in BHO than in the amount of air you breathe during any given day, which is 183mg1. Cannabis extracts routinely test at 100 parts-per-million (ppm) for butane – well below the 5,000ppm limit set by Colorado2. Since an average cannabinoid molecule is much heavier than a butane molecule (314.5 g/mol versus 58.12 g/mol),3 a full gram of BHO contains less than 0.02 mg of butane – assuming the rest is cannabinoids and molecules of similar weight to cannabinoids. That number is so low it’s in no way comparable to normal environmental exposure.
We here at ExtractionTek Solutions care deeply about safety, and I’m going to talk about some legitimate safety issues in a minute, but the fact is that the perceived dangers of hydrocarbon residuals are unfounded as they relate to professionally produced products. Yes, there are a few butane molecules kicking around in your BHO, but The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use has determined 5,000 ppm of butane to be safe in over the counter and prescription medications.3
In fact, Colorado recently raised its allowable residual levels by 525% to match these standards, much to the disbelief of consumers.4 It was a move that just didn’t feel right, but it was done to be in line with western medicine. Concentrate companies will no doubt continue operating just as they did – now they’ll just be making products that are even further below the standard than the old one.
Furthermore, the US Food and Drug Administration classifies butane and propane as “generally recognized as safe.”5 Butane isn’t a toxin; it’s an irritant. If consumed in sufficient quantity, it’ll make you cough, but it takes a lot before it becomes an actual health hazard. Only when people intentionally inhale or “huff” canned butane (like they do spray paint) does it become potentially deadly. Consumption quantity is part of the dynamic with cannabis concentrates too – consumers aren’t typically dabbing ounces of oil a day; they’re medicating with quantities better measured in fractions of grams. There isn’t enough product consumed to add up to a significant amount.
The Stigma of Amateur Production
I think some of the concern about hydrocarbons in cannabis concentrates comes from the unrelated safety issues surrounding amateur production of BHO. You’ve no doubt heard the news. “Open blasting” of lighter-grade butane is a disastrous practice, especially when performed indoors. Butane vapor fills the makeshift workspace, and an open flame or even static electricity can cause an explosion. What’s more, the tubes that amateurs are using as a material column are sometimes just PVC from the hardware store. Butane leaches other undesirable chemicals out of the PVC and into the final product. But closed loop extraction is safe if properly performed in a Class I, Division 1 workspace. No one should be open blasting, and they definitely shouldn’t be open blasting in a motel room or the kitchen of their apartment.
Pesticide use in the cultivation of cannabis is a more significant concern for concentrate products. All extraction processes – hydrocarbon, carbon dioxide (CO2) and ethanol – are likely to concentrate the pesticides, fungicides, and herbicides present in the base plant material. These toxins co-extract with the desired cannabinoids and terpenes. Just like the desired compounds, they are more of them in the resulting oil. Unlike butane and propane, pesticides are actual toxins – not irritants – and by their very nature, they’re designed to kill living things. These compounds are not acceptable within cannabis medicines and could cause struggling patients to become even sicker. If a particularly bad incident of pesticide consumption occurred, it could cause a harsh regulatory backlash for the concentrate industry as a whole.
Obtaining plant material from reputable growers who don’t use banned substances is hugely important. So is testing that plant material – both before the extraction process and after. Testing prior to the extraction process ensures that pesticides like diazinon, paclobutrazol, bifenthrin, and permethrin don’t end up in your oil. Testing after the extraction process is just as critical given the overall intent was to concentrate compounds from the plant. Base material that did not test as “hot” before extraction may contain toxins that were concentrated into detectable and harmful levels in the final oil.
Pesticide contamination can be caused by equipment components other than the plant material too, though all pesticides sources ultimately stem back to the input material. In a closed loop extractor the solvent is reclaimed after it’s run through the plant matter. Because the solvent goes back into the same tank, pesticides in the plant can enter that tank. That means a new tank that has come back from a gas supplier is potentially contaminated by previous extractions. This is a phenomenon unique to closed loop extraction – a tank of propane hooked up to a barbecue doesn’t have that expended gas returning to the tank.
Contaminated extraction machines can be an ongoing source of pesticides too. If a contamination incident occurs, extensive internally cleaning of the machine is warranted to make sure the adulterants don’t mess up the next extraction. In the event of extractor contamination, the solvents used for the internal cleaning of the machine must be complaint as well. They can be a source of harmful, banned compounds. The potential for equipment contamination again underscores the need for testing. Contaminated plant material can cause a cascade of problems that affect future extractions.
Solvent Quality and Cost
Solvent quality is paramount. Whether it’s propane, butane or CO2, the saying “garbage in, garbage out” applies. The butane-based hydrocarbon mixture found in lighter fluid is acceptable for use as lighter fluid only – not food processing or laboratory procedures. There’s a big difference between a substance intended as a fuel source and one that’s permissible as a processing agent for food and medicine.
Hydrocarbon gases must be refined to ensure they don’t contain trace amounts of lubricant and toxic compounds sometimes used in their extraction from the ground or processing. Similarly, CO2 must be refined into a purified form because it’s derived from combustion. The main offenders found in hydrocarbons include benzene, toluene, and hexane; CO2 can contain benzene and halocarbons.
I recommend at least “instrument grade” solvents for cannabis extraction and any other extracts intended for human consumption. Here’s a rundown on their purities and costs:
Instrument grade n-butane
99.5 – 99.7% purity
Approximately $5 per pound
Readily purchased from most gas suppliers
Research grade n-butane
Approximately $42 per pound
Must be custom ordered
Instrument grade n-propane
99.5 – 99.7% purity
$2.50 per pound
Readily purchased from most gas suppliers
Research grade n-propane
Approximately $17 per pound
Must be custom ordered
Using quality solvents is essential for quality extractions and patient health. For reasons both moral and financial, don’t mess around with lower grade solvents that may contain unknowns. Testing “hot” for banned substances can hurt your reputation and upend your business.
The final assurances of product purity are provided by the equipment used after the oil is pulled out of the plant by our equipment. Vacuum ovens and pumps are essential to evaporating off the final traces of hydrocarbon solvent and are just as important a part of the process as any other.
With these types of equipment, it’s a matter of quality over production quantity. I see people go for a budget product the first time around, but when they’re re-envisioning their operations the next time, they’re more likely to see value in quality. Vacuum ovens made by Cascade have proven reliable, Edwards’ dry scroll pumps are a solid choice, and we’re partial to the chillers made by MTA too. These products are on par with the quality of equipment we’re putting out, and I always think it makes sense to buy stuff that lasts. With a quality post-processing setup – and the willingness to take the time necessary to run the processes to completion – quality, compliant extracts are a lock.
Despite a wealth of evidence to the contrary, there will always be people who believe hydrocarbon-extracted concentrates are just plain bad. On some level I get it: if you can set a substance on fire, don’t put it in your body.
But the hydrocarbons just aren’t present in BHO or PHO in any appreciable quantity, and it seems the issue is a matter of philosophy – one similar to how people view GMOs (genetically modified organisms). The public perception of genetically engineered food is shaped by uncertainty and fear more than logic. GMOs have repeatedly proven safe, and there’s a broad scientific consensus that they’re indeed safe6, but some people will never come around. To them, it just doesn’t feel right. A particular segment of the market will not buy GMO food.
So it goes for cannabis concentrates. A segment of the market for concentrates will always hold out against BHO and maintain a preference for CO2-derived oils, ethanol-derived distillates or rosin. Others favor maximum terpene retention and high-quality shatter – things that are best, most easily and most efficiently achieved with hydrocarbon extraction systems. For those realists who are simply looking for great oil, ExtractionTek will keep offering reliable systems that get the job done quickly and completely.
Matthew Ellis is the President and Owner of ExtractionTek Solutions, a Denver-based manufacturer of botanical oil extraction systems that employ hydrocarbon solvents.
 U.S. National Library of Medicine. Toxnet HSDB: N-BUTANE CASRN: 106-97-8. https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/r?dbs+hsdb:@term+@DOCNO+944 (accessed July 18, 2017).
 Adlin, B.; Leafly Investigation: How Much Butane in BHO Is Too Much? Leafly. https://www.leafly.com/news/industry/butane-residual-solvent-limits-bho-cannabis-concentrates (accessed July 20, 2017).
 European Monitoring Centre for Drugs and Drug Addiction. Cannabis Drug Profile. http://www.emcdda.europa.eu/publications/drug-profiles/cannabis (accessed July 20, 2017).
 International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use. Impurities: Guideline for Residual Solvents Q3c(R5). 2011. http://www.ich.org/fileadmin/Public_Web_Site/ICH_Products/Guidelines/Quality/Q3C/Step4/Q3C_R5_Step4.pdf (accessed July 18, 2017).
 USFDA. Code of Federal Regulations. Title 21, Volume 3. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1165 (accessed July 18, 2017).
 Lynas, M.; GMO Safety Debate is Over. Cornell Alliance for Science. http://allianceforscience.cornell.edu/blog/mark-lynas/gmo-safety-debate-over (accessed July 20, 2017).