Due in no small part to nationwide medicinal and recreational marijuana legalization efforts, the usage of products containing marijuana is on the rise. In many American communities, there has also been a significant increase in the number of structural explosions related to the manufacture of cannabis (marijuana) concentrates.
Arguably, the origins of American marijuana culture can be traced to Northern California, particularly Humboldt County, giving me a unique perspective on this growing problem. Unfortunately, the hazards associated with marijuana cultivation and manufacture of marijuana concentrates has spread beyond rural California to communities nationwide.
Butane hash lab explosions can have devastating effects. These explosions can cause significant structural damage and cause serious injuries to hash oil manufacturers, innocent bystanders and firefighters. With this in mind, here we’ll define butane hash oil (BHO), describe solvent-based extraction techniques, and discuss firefighter hazards and response considerations.
Butane hash oil (interchangeably referred to as butane honey oil) is a product containing highly potent marijuana concentrates. Marijuana plants contain a chemical compound known as Delta 9 – Tetrahydrocannabinol (THC). THC is a psychoactive (mind-altering) drug that enables users to feel a euphoric “high.” THC is produced within trichomes, tiny resin glands that are connected to the surface of the flowering part of the marijuana plant known as “bud,” and in lesser concentrations is found in the plants’ leaves and stems. After marijuana bud is harvested, the remaining plant leaves can be ground up into a product known as “shake” or “trim” (figure 1).
When shake is soaked in a solvent, the THC molecule is dissolved into it. The solvent is then removed via evaporation, and the remaining product contains highly concentrated THC. For BHO manufacturing, the most common solvent is highly volatile butane gas. The resultant product is known by several street names, including “dabs,” “wax,” “honey,” “honey oil” or “shatter.” These products can then be placed into foods or smoked in an electronic vaporizer pen or an “oil rig” (a device similar to a water bong) (figure 2). These concentrates are highly potent. As a point of reference, quality marijuana bud from Northern California’s Humboldt County has a THC content ranging from 15–30 percent by volume. By comparison, cannabis concentrates can have anywhere from 60 to over 90 percent THC content by volume.
BHO extraction techniques
BHO extraction has become very commonplace. The extraction process is simple, necessary manufacturing materials are easy to obtain, and instructions are readily available online. An Internet search for “butane hash oil” provides 50-plus videos of would-be chemists demonstrating their self-proclaimed expertise in THC extraction. In addition, plant material that was previously thrown away can be processed into marijuana concentrates. Dosages of these concentrates are typically about one-tenth of a gram, with a current street value of $40–$80 per gram.
Although there are various methods to produce cannabis concentrates, this article focuses on the most common solvent-based butane extraction methods, specifically open blasting and closed-loop extraction systems.
Open blasting, named such because the butane solvent evaporates into the surrounding air, is the most common. This technique requires the following materials:
- Marijuana shake (aka trim)
- Extraction tube (made of PVC, glass, galvanized pipe, plastic bottles or various other objects which is capped at both ends)
- Coffee (or similar) filter
- Holding container (Pyrex or similar dish)
The process begins by packing dry marijuana trim into an extraction tube. The bottom cap has numerous small holes drilled into it, and the upper cap has one hole in which a nipple is attached to receive a butane canister discharge nozzle. The filter is placed between the bottom cap and the extraction tube (figures 3 and 4). This configuration allows butane to be pushed through the tube in a manner that contains the plant material, yet allows the butane to escape.
The next step, known as blasting, occurs when gaseous butane is injected into the extraction tube where it pressurizes and liquefies (figure 5). This liquefied butane serves as a solvent, pulling the THC molecule out of the plant material. This liquefied butane then drips out of the holes within the bottom cap and is captured in a holding container such as a Pyrex dish.
The final step, known as purging, draws the solvent out of the concentrate. This is accomplished by evaporation of butane into the ambient air. Purging is completed via various methods including a hot water bath (similar to a double boiler), stove top heating, or placing the Pyrex dish in the oven. Commonly vacuum ovens are used to remove the final traces of butane or other solvents.
Lastly, in a process known as winterization, the concentrates can be submerged into denatured alcohol or high-proof rum to separate out lipids and chlorophyll, further refining the product and removing any remaining impurities.
A relatively new process known as closed-loop extraction mimics the effects of the open-blasting technique without expelling volatile gases into open air. Closed-loop systems contain a large cylindrical tube where the “blasting” occurs, a collection vessel (aka “honey pot”) and a recovery tank (figure 6). Gases are moved within the system via coupled hoses and electric pumps.
Here is how the process works: Shake is placed into a large extraction tube and the tube is capped. A pressurized vessel containing anywhere from 5 to 10 pounds of solvent (typically butane) is attached to the extraction cylinder. As the cylinder is flooded with solvent, THC is stripped away from the plant material which then drops into the honey pot. The solvent is then recycled into the recovery tank via vacuum pumps or by manipulating the temperature of the recovery tank and honey pot (hot water or ice baths).
In theory, these systems are safer to operate than open-blasting techniques. However, through the introduction of either human error or mechanical failure of the system components, explosions can occur. In my department, we have responded to two explosions in the past year associated with closed-loop systems. As the manufacturers (also burn victims in these cases) were uncooperative with fire investigators, we have yet to determine the failure point of these two closed-loop systems.
When BHO extraction goes wrong, it can have catastrophic consequences. Large quantities of butane, ranging from a few dozen to over a thousand pressurized 400-mL canisters have been found inside of BHO labs. Of great concern, 40-pound (and larger) pressurized butane cylinders are also being used to fill these systems.
Butane is odorless, colorless, heavier than air, and it has a flammable range of 1.8–8.4 percent. Common ignition sources are open flame (cigarette lighters, pilot lights, gas stovetops, etc.) and electrical arcing. Butane can escape from a BHO lab, migrate low to the ground toward a distant ignition source, and flash back to the BHO lab. The associated flash fire and subsequent explosion can cause significant structural damage. Sheetrock can be lifted from ceilings, windows and doors can be blown out of their frames, and load-bearing walls can be blown off of foundations, resulting in structural collapse (figures 7, 8 and 9).
Exploding butane canisters can contribute to fire intensity, and crews fighting these fires report they are difficult to extinguish. There is also the potential for a boiling liquid expanding vapor explosion (BLEVE), as these smaller canisters or larger cylinders are exposed to fire (figures 10 and 11). In addition, due to these explosions, fire spread into concealed spaces should be anticipated. Flow path control can be very difficult as a result of damaged walls and loss of integrity of doors and window openings. Lastly, you should anticipate burn victims; their presence in these situations is common.
Over the past 3 years, Humboldt Bay Fire and other Humboldt County Fire agencies responded to over 20 BHO-related explosions. Early on, due in part to a lack of understanding of the hazards, we treated these events as we would any other structure fire—perform a size-up, make entry, search for victims, extinguish the fire, treat patients and go home. We have since learned that the increased fire intensity, possible structural compromise and potential for secondary explosions makes the risk to responders disproportionally high.
As a recent example, a small neighboring department responded to the all too familiar dispatch of “Explosion with fire, possible burn victims” in which three severely burned victims were located in front of a single-family residence. The post-fire investigation revealed heavy fire damage in a detached garage with evidence of a BHO lab. More than 800 fire-damaged butane canisters were also found. With the large quantities of butane stored within these residences, we altered our response procedures to a more cautious approach, with clearly defined trigger points for transition to defensive operations.
Humboldt Bay Fire and many other Humboldt County fire agencies have adopted the following procedures to assist in mitigation of BHO explosion-related incidents: As with any response, begin with solid fundamentals—gather intelligence while conducting a 360 and perform a risk-benefit analysis. Then observe for evidence of BHO production, including structural damage and visible debris outside of the structure (blast pattern), butane canisters or cylinders, or any associated burn victims. If such evidence is present, consider implementing the following standard operating guideline (SOG):
Response to a BHO-related explosion without fire
- Secondary explosions are possible. Keep the number of exposed personnel to a minimum.
- Secure electrical and gas utilities.
- Natural ventilation methods are preferred over mechanical (i.e., positive pressure) methods whenever possible.
- Establish a two-out team before any personnel makes entry.
- Make entry in full PPE and SCBA on air.
- Using a four-gas monitor, check for the presence of ignitable gases within Butane’s explosive range (1.8–8.4 percent). Butane is heavier than air, so monitoring should occur low to the ground.
- Extinguish any smoldering fire and secure all possible ignition sources in the affected area.
- Search for and remove victims.
- Treat patients and transport as appropriate.
Response to a BHO-related explosion with fire
- As soon as evidence indicating a butane hash lab is observed, ensure that all responding personnel and the dispatch center are notified over the incident’s command and tactical channels.
- Broadcast an emergency alert tone notifying personnel of the hazard.
- As appropriate, conduct a primary search.
- Once the primary search is complete or if the risk-benefit analysis indicates it is unsafe to search, transition to defensive operations.
- Offensive operations may occur in nearby residences or attached exposures, such as adjoining apartments in an apartment complex, if evidence of structural compromise is absent.
The occurrence of BHO lab explosions is significant. Due to their prevalence, explosive nature, and significant risk of injury to occupants and first responders, some within the law enforcement community are describing hash labs as the “modern meth lab problem.” Unfortunately, due to marijuana concentrates’ increasing popularity, the prevalence of these labs is likely to rise. By recognizing BHO lab indicators and their associated hazards, we can modify our approach, thereby reducing risk of harm to our personnel while fulfilling our core mission to protect lives and property.