Control Banding in Cannabis Production

Authored by Chemscape’s Angela Wheeler, CIH, CSP

Cannabis production is an example of applying control banding to guide the assessment and management of workplace risks for substances for which there is no Occupational Exposure Limit (OEL). The commercial production of cannabis is a new and rapidly expanding industry of small and medium-sized producers who typically lack access to an occupational hygienist and have no exposure or toxicological data from which to estimate an OEL. 

Although cannabis is considered a food-grade pharmaceutical substance at the consumer end, the production environment, consisting of large greenhouses and process equipment, can present hazardous exposures for workers. Many workers have daily exposure to cannabis on a scale and frequency that can pose health hazards to their skin and respiratory system. Toxic reproductive effects are also associated with the tetrahydrocannabinol (THC) and cannabidiol (CBD) components of cannabis. Most recently, there was a fatality due to occupational asthma due to ground cannabis exposure.

Scenario 1: Control Banding of Cannabis (Hemp) Oil

Cannabis (hemp) oil extracted from the cannabis seeds is used for cooking, aromatherapy, and natural perfumery. Section 2 from a cannabis oil Safety Data Sheet (SDS), which identifies relevant hazard statements associated with the Globally Harmonized System for Classification and Labelling of Chemicals (GHS), is provided in Table 1. According to COSHH Essentials, a control banding scheme from the United Kingdom’s Health and Safety Executive, the GHS hazard statements place cannabis oil in Group C, the designation for substances that are “somewhat hazardous.” Banding simplifies hazard communication, signaling to workers that the oil is a moderate-priority hazardous substance. The hazard band provides a concentration range of >0.5–5 ppm so that an IH can gauge whether exposure controls are appropriate, effective, and maintained. 

Table 1: Cannabis (Hemp) Oil GHS Classification
 

Control banding of three different exposure profiles—also known as similar exposure groups (SEGs)—using COSHH Essentials generates three different control approaches (see Table 2). Personal protective equipment is part of the control approach for each level to reduce the potential for skin irritation and sensitization.

Table 2: Cannabis Oil Control Approach According to Work Position
 

Scenario 2: Control Banding of Cannabis Plant

Cannabis plants are grown, harvested, and distributed as feedstock for cannabis consumables. The GHS classification from section 2 of an SDS for a cannabis plant is provided in Table 3. COSHH Essentials health hazard banding would classify this substance as Group D or “most hazardous.” This band signals a high-priority hazardous substance to workers, supervisors, and OEHS personnel. The concentration range for this band is <0.01 mg/m3 as a working criterion for verifying the applicability and performance of exposure controls. 

Table 3: Cannabis Plant GHS Classification
 

Table 4 lists three different exposure profiles (that is, SEGs) with different control approaches. Containment features prominently because the substance rises to Hazard Group D. This level of control is more difficult in agricultural settings such as large greenhouses. Even engineering controls such as local exhaust ventilation, fume hoods, and ventilated work benches may be impractical for harvesting and monitoring growth. In these situations, the OEHS professional will typically rely on procedures that maintain low dust levels in large or outdoor workspaces with general ventilation and full PPE (including respirators, gloves, coveralls, and decontamination protocols). COSHH Essentials Direct Advice Sheets for industry-specific details.

Table 4: Cannabis Plant Control Approach According to Work Position
 

Scenario 3: Control Banding of Cannabis Dust

Cannabis processing and extraction will create plant particulate. This dust has been shown to cause respiratory disease, sensitization, and anaphylaxis. The crucial hazard for cannabis dust would be a GHS classification of Respiratory Sensitizer, shown in Table 5. COSHH Essentials health hazard banding would classify this substance as Group E or “Special Cases - Extremely Hazardous.” This band signals a high-priority hazardous substance to workers, supervisors, and OEHS personnel. There is no acceptable airborne concentration for this band; expert (industrial hygiene) advice, containment and other applicable control measures are required to reduce exposure to As Low As Reasonably Practicable. 

Table 5: GHS Classification of Cannabis Dust
 

Table 6 emphasizes the need for an exposure control plan where cannabis is ground into a powder, handled or packaged. Controls may include the following: 

• Automation, enclosures, fume hoods or glove boxes. 

• Increased ventilation/LEV, restricted work areas, decontamination practices. 

• PPE, including N95/P100 or powered, air-purifying respirator (PAPR). 

• Strict housekeeping protocols.c 

• Medical Surveillance/Fitness for Work Assessments. 

• Job rotation or reassignment for exposure avoidance. 

• Preventive maintenance & monitoring of controls. 

 Table 6: Cannabis Dust Control Approach According to Work Position
 

Note that only a fraction of workers may be affected, and symptoms are typically delayed because respiratory sensitization involves an allergic response, called respiratory hypersensitivity. Therefore, any reports of breathing trouble need to be taken as an indicator of potential overexposure to the workforce and a call for preventive action. See COSHH G402 (hse.gov.uk) for direct advice on health surveillance for occupational asthma.

The Value of Control Banding

Control banding offers an actionable plan in the absence of OELs. Implementing controls identified through a scheme like COSHH Essentials takes less time than creating a sampling plan or waiting for lab results. OEHS personnel can confirm exposure control by measuring the effectiveness of containment and engineering controls and adherence to PPE and safety policies. Using control banding transfers the bulk of industrial hygiene time, budget, and resources from monitoring and measuring toward higher-value exposure control and confirm activities, protecting workers in the present.  

About the Author:

Angela Wheeler is program manager for Chemscape’s CHAMP product as well as a CIH, CRSP, and SDS Registered Author with 20 years of EHS experience in various industries in Canada and the U.S. She is also the vice chair for the AIHA Cannabis Industry Health and Safety Committee. The focus of this committee is the development of a health, safety, and environment guidance document for cultivation, processing, manufacturing, distribution, and sales of cannabis products, regulation review and response, and health and safety advocacy.