Comment on Deeb et al.: interpretation of breath cannabinoids and implications for impairment.

This letter addresses the article by Deeb et al. describing the analysis of cannabinoids in exhaled breath. While the study represents a technical advancement in breath-based detection, several interpretive and analytical limitations warrant clarification. The manuscript discusses potential impairment-related applications despite the absence of direct measures of impairment. Existing literature, including controlled clinical studies and government reports, indicates that THC concentrations in biological matrices cannot be used as a reliable indicator of impairment. Additionally, key variables influencing cannabinoid exposure, including dose, potency, and inhalation behavior, were not controlled, further limiting interpretability. Analytical concerns are also noted, including subpar chromatographic resolution (Rs ≈ 0.9), which may compromise accurate identification and quantitation of structurally similar cannabinoids. These issues highlight the need for caution in interpreting breath cannabinoid data, particularly in forensic contexts where conclusions regarding impairment may carry significant consequences.