Three Oral-Fluid Examples Cannot Establish a Cannabis Dose–Response Rule

A cannabinoid assay can work analytically without establishing how saliva concentrations track dose or impairment. A 2019 method paper included only three illustrative participants, making its clinical application a demonstration rather than a dose–response validation.

A broad panel was the analytical achievement

Sobolesky and colleagues developed liquid chromatography–tandem mass spectrometry for ten cannabinoids and metabolites in oral fluid without hydrolysis. The panel included THC, CBD, minor cannabinoids and glucuronide conjugates, allowing distinct compounds to be measured separately.

The lower quantification limit was 0.4 ng/mL for six analytes and 1 ng/mL for four others. Validation included precision, bias, interference, extraction and matrix-effect experiments. Those repeated laboratory measurements are valuable, but they do not increase the number of people in the clinical illustration.

The three participants were not a population comparison

The application used specimens from one placebo participant, one lower-THC participant and one higher-THC participant. With only one person per condition, differences between conditions can also reflect differences between those individuals.

The placebo participant had predose THC and later detectable cannabinoids. That observation cannot by itself establish laboratory contamination, exposure during the session, or chemical conversion. A predose result is part of the exposure history that must be interpreted, rather than erased because the subsequent assigned product was placebo.

A negative analyte does not invalidate the whole panel

Several metabolites and conjugates were not detected in these three participants. Their absence does not show that the validated method was unable to detect them, nor that they never occur in oral fluid. Analytical capability and observed prevalence in a tiny convenience demonstration answer different questions.

Likewise, a measurable parent THC result in oral fluid does not supply a corresponding blood concentration or a demonstrated degree of impairment. The authors expressly framed the application as an analytical demonstration, not a pharmacokinetic or impairment study.

For a forensic review, distinguish validation replicates from independent participants and identify what each experiment actually tested. Our discussion of concentration and impairment addresses the additional evidence required before connecting a cannabinoid measurement to functional capacity.

Primary research

Philip M. Sobolesky and colleagues. Clinica chimica acta; international journal of clinical chemistry (2019). Validation of a liquid chromatography-tandem mass spectrometry method for analyzing cannabinoids in oral fluid.