The main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), and its metabolites are emerging organic contaminants that have been detected in waste and surface waters around the globe. This paper aims to review the recent literature regarding the detection, occurrence, and treatment of THC and its main metabolites, 11-hydroxy-Δ9-tetrahydrocannabinol (THC-OH), and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). Detection methods for THC, THC-OH, THC-COOH, and other cannabinoids have advanced in recent years with the development of sensitive analytical techniques (e.g., gas chromatography or liquid chromatography with mass spectrometry). Using online or offline solid phase extraction (SPE) has enabled detection at nanogram and picogram per litre concentrations. THC-COOH has been detected in untreated and treated wastewater up to 2500 and 750 ng·L–1, surface water over 500 ng·L–1, and tap water up to 1 ng·L–1. Adsorption is likely a significant pathway for the removal of THC that is unmetabolized in wastewater or surface water, due to its low aqueous solubility. THC and THC-COOH have been shown to cause oxidative stress to aquatic species. The few studies of potential treatments for THC-COOH have shown that chlorination and UV oxidation lead to potentially form transformation by-products, which would be toxic in aquatic environments.
Emerging Organic Contaminants in Chinese Surface Water: Identification of Priority Pollutants
