A Critical Review of Cannabinoid Metabolites: From Biotransformation to the Urban Water Cycle and Reported Monitoring.

Castellanos A.; Sun M. · Toxics · 2026

**Background & Methods** This is a critical review examining cannabinoid metabolites from biotransformation through environmental detection and monitoring. The review synthesizes existing literature on cannabis metabolism, the environmental fate of metabolites released via human excretion into wastewater systems, and analytical methodologies for detecting cannabinoid compounds in aquatic environments across global regions. **Key Findings** • Cannabinoid metabolites are released into urban water cycles through bodily excretions, providing potential biomarkers for population-level cannabis consumption patterns and contamination assessment. Detection of tetrahydrocannabinol (THC), cannabinol (CBN), cannabidiol (CBD), cannabigerol (CBG), and cannabichromene (CBC) metabolites can track usage trends as cannabis legalization expands globally for medicinal and recreational purposes. • Liquid chromatography paired with tandem mass spectrometry (LC-MS/MS) is identified as the gold-standard analytical method for cannabinoid detection due to superior reliability, specificity, and cost-effectiveness compared to gas chromatography-mass spectrometry (GC-MS), which carries risks of heat-induced degradation of cannabinoid compounds. • Growing cannabis consumption rates resulting from expanded legal status and accessibility present emerging environmental and public health concerns, including wastewater contamination and potential ecological impacts that require enhanced monitoring protocols and remediation strategies. **Dosage & Administration** Not reported. This review does not address human dosing or routes of administration for cannabis products. **Safety & Adverse Effects** Illicit cannabis consumption can induce adverse effects within the human body in addition to preexisting health risks and complications; however, the review does not detail specific adverse effects. The primary safety concern identified relates to environmental and public health impacts from metabolite contamination in aquatic systems rather than direct human toxicity. **Evidence Quality** This review is limited by its synthesis of existing literature without original empirical data collection. The quality of evidence depends on the methodological rigor of cited studies, which are not explicitly evaluated. As a narrative critical review rather than a systematic review with defined inclusion/exclusion criteria, it represents moderate-to-low levels of evidence. Key limitations include the lack of quantitative risk assessment data, limited understanding of environmental persistence and toxicology of cannabinoid metabolites in aquatic ecosystems, and potential publication bias toward detection studies using LC-MS/MS methodology over alternative approaches.

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