Law enforcement officers at outdoor concerts were exposed to secondhand cannabis smoke but at levels far below those causing impairment | Research

The takeaway

Police officers working outdoor concerts in a legal cannabis state had measurable THC in their breathing zones and 34% had a THC metabolite in urine, but levels were far below impairment or drug-test thresholds.

Occupational health professionals, law enforcement agencies, event security companies, and policymakers designing workplace cannabis exposure standards.

34% had urine THC metabolite, but orders of magnitude below drug test cutoff

What the researchers found

THC was detected in personal air samples (53-480 ng/m3) and area samples (up to 330 ng/m3). A THC metabolite (THC-COOH) was found in post-event urine of 34% of officers, but at concentrations orders of magnitude below the 50 ng/mL drug-screening cutoff. No THC or metabolites were detected in any blood sample. 31% reported eye irritation, 21% dry mouth, 21% headache.

Why it matters

As cannabis legalization expands, workers in entertainment, security, and law enforcement face occupational secondhand exposure. This study provides the first data on real-world workplace exposure levels at outdoor events.

The numbers in context

29 officers. Personal air THC: 53-480 ng/m3. 34% had THC-COOH in post-event urine (<1.0 ng/mL vs. 50 ng/mL cutoff). 0% blood positives. Symptoms: eye irritation 31%, dry mouth 21%, headache 21%, coughing 21%.

How the study worked

Convenience sample of 29 law enforcement officers at two outdoor stadium concerts in July 2018 in a legal cannabis state. Personal and area air sampling for THC. Pre- and post-event urine (n=58) and post-event blood (n=29) analyzed by UHPLC-MS/MS and HPLC-MS.

What this study cannot tell us

Convenience sample of only 29 officers at two concerts at one venue. Outdoor setting may underestimate exposure at indoor events. Blood detection limits may have been too high to detect very low concentrations. Symptoms were self-reported.

How to read the evidence

Well-designed occupational exposure study with biological monitoring, but small convenience sample at a single outdoor venue.

When this study was published

2020 study using July 2018 data. One of the first occupational secondhand cannabis smoke exposure studies.

The bigger picture

While secondhand cannabis smoke exposure at outdoor events appears unlikely to cause impairment or positive drug tests, the respiratory and ocular irritation symptoms raise questions about chronic occupational exposure for security personnel.

Questions still open

Would indoor concert venues show higher exposure levels? Could cumulative exposure over many events affect long-term health? Are current workplace drug-testing thresholds appropriate given occupational secondhand exposure?

Common questions

Could secondhand cannabis smoke at a concert cause a positive drug test?

In this study, all urine THC metabolite levels were orders of magnitude below the standard 50 ng/mL drug-screening cutoff, and no THC was detected in blood. Occupational outdoor exposure appears very unlikely to trigger a positive test.

Could officers have gotten a contact high?

The airborne THC levels were far below concentrations associated with psychotropic effects. No officers reported feeling intoxicated, though some experienced eye irritation and dry mouth.

Read the original research

Occupational Exposure to Secondhand Cannabis Smoke Among Law Enforcement Officers Providing Security at Outdoor Concert Events.

Annals of work exposures and health, 64(7), 705-714

View on PubMed ↗Publisher’s paper ↗

Citation

Wiegand, Douglas M; Methner, Mark M; Grimes, George Reed; Couch, James R; Wang, Lanqing; Zhang, Li; Blount, Benjamin C. (2020). Occupational Exposure to Secondhand Cannabis Smoke Among Law Enforcement Officers Providing Security at Outdoor Concert Events.. Annals of work exposures and health, 64(7), 705-714. https://doi.org/10.1093/annweh/wxaa025