by Meghan McCormick, Ph.D, Spektrum Cannabis Technologies

With the expanding decriminalization of marijuana and hemp and increasing market demand for cannabis concentrates, more people are assuming the role of pseudo-chemists or lab technicians without formal training. People no longer need to ‘break bad’ by extracting and processing cannabis in their garages, kitchens, or old RVs. Commercial laboratory spaces are becoming more common. Unfortunately, without formal laboratory training, appropriate laboratory safety habits are often not established. The ‘whatever-it-takes’ mentality plus some questionable lab techniques add up to be quite dangerous in a pursuit for the ‘good stuff.’ 

Solvents used for extraction, though often odorous, are clear and colorless and therefore invisible in vapor form. They are often handled in the lab like water. For those manufacturing cannabis concentrates for retail, the focus has been on possible regulations set by the FDA, but these new, small businesses are also under the jurisdiction of OSHA. While studying industrial hygiene standards written by OSHA, most safety practices seem like common sense, but only after the chemical hazards are recognized. 

For more in-depth safety standards and fire codes for non-glassware or non-laboratory-scale (read: industrial-scale) extraction and processing equipment, ANSI/CAN/ UL/ULC 1389 or NFPA 1 Chapter 38 are great starting points. 

Most of What We Breathe Is Invisible

As mentioned above, the solvents used to extract and process cannabis are either gases compressed into their liquid form or clear, colorless organic liquids. [Note: here ‘Organic’ means a substance that contains carbon, not the label you find at your grocery store]. These solvents include ethanol, propane, butane, pentane, hexane, isopropyl alcohol, methanol, acetonitrile, and other less common ones. 

The danger of these solvents is that even when they are cold they vaporize easily enough for inhalation, some without harsh odors as a warning. Opening containers, glassware, or vessels without proper ventilation or PPE (personal protective equipment) exposes laboratory workers over a short time and many times a day. This exposure can occur during simple acts of pouring, transferring, heating, drying, mixing, or weighing on a balance. While many of the solvents used have a GRAS designation (generally regarded as safe) by the FDA, this label is used for food additives with the intention of ingestion, not inhalation. There are a few research studies on the toxicological effects of breathing in these VOCs (volatile organic compounds) in a short period of time. However, chronic studies of consistent exposure for years are rare. NIOSH, or the National Institute for Occupational Safety and Health, provides a decent summary of worker exposure studies for common industrial chemicals. Some of which can cause respiratory effects that evolve into allergies or even neurological damage. Unfortunately, most of the toxicological literature available can be decades old.

Yet laboratory technicians are not the only ones exposing themselves to a potential hazard. Working on large-scale extraction equipment, workers come into contact with large plums of high concentrated VOC when opening extraction tanks and vessels. This process happens many times a day when workers reach in to load and unload bags of cannabis biomass. Exposure also occurs through skin contact, as many of these solvents absorb into uncovered skin.

Gases under pressure are yet another non-chemical hazard. Compressed gas tank cylinders need to be transported and stored safely to keep them from falling over and crushing limbs. If a cylinder valve breaks off, they turn into a projectile missile, or they become damaged enough to rupture and release thousands of liters of suffocating gas within minutes or seconds.

Carbon dioxide solid in the form of ‘dry ice’ is often used in large amounts for cold traps in cannabis oil processing. Dry ice easily sublimes, where the solid form converts directly into a gas. Gaseous carbon dioxide is much heavier than general air and can easily displace oxygen in closed-off storage areas. Oxygen sensors, proper ventilation, and limited exposure help to avoid hazardous side-effects of oxygen deprivation.

The Tools to Keep Everyone Safe Are Out There

Any workplace that handles or stores chemicals should have the corresponding Safety Data Sheets (SDS) of the chemical. These are usually obtained from the manufacturer of the chemical, but there are also free databases online for easy access. All SDS’s should be available for easy access to workers who handle or are in an environment that uses chemicals.

OSHA also provides its own chemical database system that lists the physical properties of chemicals as well as their permissible exposure limits (PELs) and short-term exposure limits (STELs). These limits are used for compliance purposes, but in short, they provide a rough guide for how dangerous it is to breathe in some of these chemicals. Note that OSHA’s exposure limit guidelines may be outdated as many have been written 50 years ago when OSHA had been founded! For the latest guidelines visit NIOSH and ACGIH.  These organizations/agencies keep up with current toxicological research and provide more up-to-date exposure limits that are sometimes significantly lower. Air sampling of your workers can always be done through an AIHA-accredited laboratory that will send out certified industrial hygienist to sample during a work shift.

Any industrial hygienist will tell you that the use of PPE is the last line of defense against chemical hazards and exposure. Engineering controls like proper room ventilation and local ventilation, including fume hoods, exhaust hoods, and elephant hoses, are some of the best ways to avoid exposure through inhalation. Fume hoods are almost always found in laboratory spaces; however, it’s easy to form bad habits when using them. For example, storing large objects and numerous chemical bottles inside the hood significantly blocks the proper airflow that needs to occur to make sure any vapor is properly ventilated. The sash (or glass door) should always be kept as low as possible and especially below the chin of the person working at the hood. Newer models of fume hoods have airflow monitoring devices and alarms systems to make sure the face velocity of the hood is between 80 and 120 fpm (feet/min).

Finally, PPE that fits comfortably, doesn’t interfere with the flow of work, and is rated properly for the hazards of the chemicals used, is a definite requirement when working with chemicals even when other controls are in place. 

When effective local ventilation is not available for situations where a large plume of solvent vapor is expected (e.g., opening an extraction vessel to remove biomass bags), a full-face or half-face respirator is the best option to prevent exposure. 

Respirators have specific cartridges that stop the inhalation of certain hazards. VOC cartridges are required to keep out the organic solvents most used. However, respirators will only protect as they meant to be if they are fit-tested, and properly cleaned and stored. 

Last, eye protection via safety glasses is an obvious and thankfully well-practiced habit even in workplaces without chemicals. Unfortunately, the commonsense practice of making sure workers are wearing long pants, shirts with sleeves or lab coats, and closed-toe shoes (preferably non-absorbent) is more difficult to enforce if the location is in warmer climates.

All that said, for those who are dabbling in the new, exciting world of cannabis extraction, let’s hope they are following Walter White’s lead and suit up before they get to work.

With more than 15 years of experience working and teaching in chemistry laboratories, Meghan McCormick, Ph.D. is the Senior Chemist and a part of the Herban Legends team at Spektrum Cannabis Technologies, an innovative, fit-for-purpose engineering services company. Meghan serves as the resident expert in the chemical processes that occur during cannabis extraction and post-processing and has helped design and test the Spektrum industrial-scale cannabis processing modules. Meghan worked as a Senior Chemist for the OSHA Salt Lake Technical Center for 3 years. She received her Ph.D. in Inorganic Chemistry at Indiana University studying organometallic electrocatalysis and anti-cancer prodrug activation mechanisms.