Fatal Occupational Asthma in Cannabis Production — Massachusetts, 2022

Discussion

Cannabis industry employees are exposed to large quantities of ground product in some work areas, such as flower grinding and preroll production. Asthma, allergic rhinitis, and urticaria have been reported among cannabis production workers (2,3). Several allergens have been identified, and irritants are present as well (1–3). Work-related asthma includes occupational asthma (i.e., new-onset asthma induced by sensitizers or irritants) and work-exacerbated asthma (i.e., preexisting asthma worsened by work exposures) (4). In this case, absence of a history of asthma and the temporal relationship between work exposure and asthma signs and symptoms are consistent with a diagnosis of occupational asthma. Airborne respirable dust and endotoxin levels below occupational exposure limits do not exclude a sufficient level of airborne allergen to trigger asthma and other allergic symptoms.

Enhanced surveillance for work-related asthma in the state of Washington identified seven asthma cases among employees in indoor cannabis production facilities (5). Three employees with work-exacerbated asthma discontinued cannabis employment; one with occupational asthma was symptomatic in two different cannabis facilities separated by a 2-year asymptomatic period while unexposed.

In a study of employees at an indoor Washington cannabis production facility, 13 of 31 employees had symptoms suggestive of asthma (i.e., presence of either an attack of shortness of breath, an attack of asthma, or the use of asthma medication) (6). Among 10 employees with occupational allergy symptoms, seven had abnormal spirometry, and five had skin prick testing consistent with cannabis sensitization. Five employees had abnormal or borderline fractional exhaled nitrogen oxide testing, which is used as a marker of airway inflammation in asthma management; results increased significantly across the work week, indicating an increase in airway inflammation.

Fatal asthma can occur even with disease that is considered mild; disparities in income, education, and access to health care are risk factors associated with death (7). Work-related asthma has also been associated with poorer asthma control (8). Additional risk factors for the deceased employee in this case report include the emergency department visit, recent use of oral glucocorticoids, increased dyspnea and bronchodilator inhaler use without inhaled glucocorticoids, continued exposure, and lack of a provider with expertise in occupational allergies (7,9).

Occupational asthma is generally associated with a latency period of months to years between first exposure and symptoms (10). For example, fatal occupational asthma related to exposure to powdered shark cartilage was reported 16 months after exposure onset (10). Although latency from this employee’s first occupational cannabis exposure to symptom onset was short, latency from first exposure was longer because of personal cannabis use. Cross-sensitivity between cannabis and plant allergens might also have predisposed this employee to cannabis sensitization (3).

Limitations

The findings in this report are subject to at least three limitations. First, although the employee’s course is consistent with fatal asthma triggered by cannabis allergy, this finding was not evaluated by skin testing or specific immunoglobulin E tests. Second, airborne cannabis allergen levels could not be assessed. Finally, as in many occupational fatality cases, investigators were not able to speak with the employee, requiring details to be obtained from other sources such as medical records and interviews with coworkers and next-of-kin.

Implications for Public Health Practice

Providers and public health professionals would benefit from additional research into prevalence and risk factors for cannabis-related occupational allergies. Development and implementation of strategies to protect workers are critical in this rapidly expanding industry. Measures to protect employees might include determination and control of exposures, training of employees and facility managers, correct use of personal protective equipment, and medical management of employees with work-related symptoms, which might require cessation of work and workers’ compensation (Box). It is important to recognize that work in cannabis production is a risk for occupational allergies.