Exhaled Breath Condensate Is a Distinct Matrix for Cannabis Testing
Cannabinoids can be recovered from exhaled breath condensate, but this does not make condensate equivalent to a filter-pad breath sample or a validated impairment test. A small proof-of-concept study demonstrated analytical feasibility in an aqueous breath matrix.
What the investigators collected
Berry and colleagues analyzed condensate from 12 participants who inhaled their own cannabis and two participants who did not use cannabis. Samples were obtained before use and at approximately 0.7 and 1.7 hours afterward. Participants used different products and inhaled ad libitum rather than receiving a uniform delivered THC dose.
Condensate captures water together with material associated with breath aerosols and potentially vapor. Unlike a filter-pad approach, its collection does not require assuming that all recoverable THC is carried in particles. The resulting units and recovery characteristics belong to that particular collection system.
THC was present before the experimental use
Five of the 12 cannabis users had detectable THC in baseline condensate. THC was detected in all 12 at approximately 0.7 hours, although one result was only a trace. Concentrations decreased by the later collection. CBN, CBG and occasional other cannabinoids were also found after use.
Neither non-user had detectable cannabinoids. That supports the absence of detectable contamination in those controls, but two controls cannot establish a universal environmental-contamination rate or rule out every possible source.
Feasibility is not diagnostic accuracy
Average condensate mass did not significantly change across sampling times, and most within-person mass variation was relatively modest. These collection observations support further study; they do not establish a THC concentration that separates impaired from unimpaired drivers.
Product variability, small sample size, recovery limitations and pre-use positivity constrain the interpretation. The post-use time points overlapped an expected period of possible impairment, but temporal overlap alone does not validate a classifier against actual individual performance.
A report should identify whether “breath THC” means condensate, aerosol collected on a pad, or another system. Comparing raw values across those matrices without validated normalization can mislead. The broader distinction between exposure and impairment is explained in our THC blood-level discussion.
Primary research
Jennifer L Berry and colleagues. Journal of Breath Research (2024). Cannabinoids detected in exhaled breath condensate after cannabis use.
