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From seed to smoke: Marijuana concentrates and manufacturing risk

By Lucian McMahon July 10, 2017

Marijuana processing

In the first installment of our series on recreational and medical marijuana, From seed to smoke: Marijuana cultivation, we discussed potential risks in marijuana cultivation and some state responses. This article addresses potential risks related to manufacturing finished marijuana products.

Understanding the hazards

Sparking up a doobie isn’t the only way to consume marijuana these days. In states that permit marijuana use, so-called “marijuana manufacturers” or “processors” have begun producing a variety of finished marijuana products, ranging from vaporizable hash oil to cannabis-infused cooking butter to liquid cannabis tinctures to non-psychoactive topical creams.

The wide variety of marijuana products available has created a range of potential risks to consider. Some of these considerations include whether there are fire or explosion hazards associated with using chemical solvents to extract highly potent oils. Are there food safety protocols during production of cannabis-infused brownies? And are there controls in place for dosages and potencies to ensure consumer safety?

Varying state regulations

States permitting marijuana use have different regulations or laws in place to address who can produce, manufacture, or process marijuana into various finished products—and how.

For example, under Oregon law, there are five retail marijuana license types available, including one for marijuana processing, which the state defines as a “business that will transform the raw marijuana into another product (topicals, edibles, concentrates, or extracts).” A licensee may hold multiple license types, allowing the same business be a licensed processor and retailer of marijuana. In contrast, under Washington law, such “vertical integration” among recreational marijuana companies is prohibited; processors cannot also hold a license to sell retail marijuana.

Marijuana concentrates are exactly what they sound like: products that contain concentrated dosages of the cannabinoids found in marijuana plants. They are generally produced by extracting these cannabinoids, including THC, from the plant itself. THC (Tetrahydrocannabinol) is the psychoactive chemical in marijuana that reportedly gives users a euphoric feeling. 

These concentrates may be consumed directly or may be infused into other marijuana products, such as edibles and drinks. Concentrates and infused products will often contain higher THC levels than marijuana consumed directly, though some concentrates may deliver non-psychoactive cannabinoids such as cannabidiol (CBD). A very common type of concentrate is “hashish,” a compression of THC-rich resins found on the marijuana plant, which can reportedly be extracted either through sifting of plant materials or other water-based techniques.

Water-, food-, or solvent-based concentrates

States differ in how they classify and regulate the manufacture of marijuana concentrates. For example, Colorado regulations for recreational marijuana generally distinguish between three types: water-based, food-based, and solvent-based concentrates. Water-based concentrates are defined as those that involve extraction “through the use of only water, ice or dry ice,” such as hashish. Food-based concentrates use “propylene glycol, glycerin, butter, olive oil or other typical cooking fats.” In Colorado, solvent-based concentrates are limited to “butane, propane, CO2, ethanol, isopropanol, acetone and heptane."

Oregon, in contrast, distinguishes between two types of recreational marijuana manufacture: concentrates and extracts. Under Oregon's regulations, concentrates are defined as those substances that obtain cannabinoids, in part, using a “mechanical extraction process,” such as sifting and compressing to produce hashish, or are chemically extracted without hydrocarbon-based solvents, such as water, oils, or fats. Extracts, on the other hand, obtain their cannabinoids, in part, using hydrocarbon-based solvents like butane, or using CO2 with high heat or pressure.

Butane hash oil—fires, explosions, and impurities

The concentrate that results from extracting THC using oils or chemical solvents is often called “hash oil,” which can be vaporized, smoked, or ingested. There are different types of hash oil, depending on the solvent used, but butane hash oil in particular has gained increased attention in recent years.

Butane hash oil is a highly potent marijuana concentrate that uses pressurized butane to extract THC from the plant. The resulting oil can often contain up to 80 percent THC. By comparison, the average THC level in Colorado marijuana plants has reportedly been found to be 18.7 percent. There have been a number of reported concerns related to the manufacture of butane hash oil, including potential fire, explosion, and product contamination hazards.

For one, butane is a highly explosive gas that can quickly spread throughout an enclosed area and ignite. There have been a number of reported explosions resulting from butane ignitions during hash oil production. For example, this year The Oregonian reported that the Oregon Occupational Safety and Health Administration fined a marijuana manufacturer for “a series of workplace violations” related to a hash oil explosion. According to the article, the cited company failed, in part, to adequately ventilate its premises and have an "adequate electrical system." The Oregonian further reported that there have been other marijuana-related OSHA citations for various violations issued to at least three other businesses. Similarly, last year the Albuquerque Journal reported that the federal OSHA had fined a New Mexico medical marijuana dispensary for employee health and safety violations after two employees were injured in a hash oil production-related explosion.

Production for personal consumption

Of particular interest, Colorado's Amendment 64, which legalized recreational marijuana use, reportedly permitted adults 21 or older to produce hash oils for personal consumption. However, the slate of hash oil-related explosions reportedly prompted the state to amend its laws to prohibit private individuals from producing hash oils using flammable liquids, including butane.

For commercial operators, various states regulate the manufacture of concentrates like hash oil to ensure health and safety. For example, Oregon’s recreational marijuana regulations require, among other things, proper ventilation and ignition control, code-compliant electrical installations, and a professional grade closed-loop extraction systems. And Colorado requires an industrial hygienist or professional engineer report certifying compliance with recreational marijuana concentrate manufacturing regulations and other codes.

There have also been reported concerns that butane or other solvent-based concentrate products may contain residual levels of the extraction chemicals, reducing their purity. Consuming concentrates with high levels of residual solvents through inhalation - whether via vaporization or smoking - could potentially expose users to hazardous fumes.

To address this concern, various states with legal recreational and/or medical marijuana have introduced residual solvent limits for finished concentrates and have specified the quality of solvents to be used. Washington’s recreational marijuana law, for example, specifies “parts per million for one gram of finished extract cannot exceed 500 parts per million or residual solvent or gas.” Colorado's recreational marijuana law specifically limits residual limits per gram for chemical solvents, including butane, which is limited to less than 5,000 parts per million. Regarding quality, Oregon, for example, requires that any “hydrocarbon-based solvent,” including butane, be “at least 99 percent purity” for recreational marijuana products.

A Cannabist article reports that CO2 hash oil may be a safer alternative production technique than using butane - the CO2 is compressed to a high pressure, turning it into a liquid that can extract the cannabinoids from the plant. It may reportedly be safer because it is non-flammable and doesn’t use chemical solvents. However, the article notes that the equipment needed to produce commercial scale CO2 hash oil may be prohibitively expensive.

Other considerations—medical and recreational foods, drinks, and potencies

As we mentioned earlier, inhalation, like vaping hash oil, is only one of several methods of marijuana consumption. Concentrates and other marijuana-based products can deliver THC by infusion into food and drinks.  

So-called “edibles,” including the colloquial “pot brownies,” are foods or confections that are cooked with cannabis- or concentrate-infused butter or oils. Marijuana manufacturers or processors often cook such infused foodstuffs or brew infused beverages, like tea, for retail sale.

Two potential considerations related to the manufacture of ingestible marijuana products include: (1) safety of preparation and (2) safety of consumption.

Producing marijuana edibles or drinks may expose manufacturers to similar risks found in the traditional food preparation industry, including the potential for product contamination. States that permit marijuana manufacture impose various restrictions to address food safety concerns. For example, recreational marijuana processors in Oregon that possess a cannabinoid edible endorsement must, in part, possess a food establishment license and abide by applicable regulations and may not produce any foodstuff that does not contain cannabinoids. Colorado regulations require, in part, that manufacturers of recreational edibles have a food handler certificate, complete a training course, and be in compliance with applicable food handling and safety laws.

The consumption of marijuana edibles or drinks may also expose manufacturers to potential risks. Of particular concern is the dosage and potency of the resulting product, not to mention that there is the potential that cooking or preparing marijuana products may increase the potency. States have begun addressing this issue through THC serving requirements, product testing, and product labeling to avert users ingesting potentially dangerous levels.

For example, Colorado law requires all edible marijuana products to have “clear single servings of 10 mg THC, with no more than 100 mg per product.” Washington imposes similar serving limits. However, individuals may react differently to THC dosages, which could lead to potentially dangerous results regardless of the serving size in question.

Moving forward

We have only discussed a selection of potential risks and considerations related to manufacturing marijuana products. How to safely manufacture these products and how to mitigate any potential health risks from their use remain evolving issues. The ISO Emerging Issues team continues to research and track potential considerations related to marijuana. You can find more of our research on ISOnet (ISOnet login required).

Stay tuned for our next installment, when we'll take a look at potential risks related to selling marijuana products from both retail and medical establishments.

Lucian McMahon is a product development specialist with the ISO Emerging Issues team. You can contact Lucian at