Key Takeaways & Executive Findings
- •• • DZP is a benzodiazepine anxiolytic with low volatility and slight water solubility, yet it is frequently detected in fishery water and aquatic products, despite being banned in animal food in China; a survey of 23 regions found 14 out of 35 commercial fish bait products contained DZP, indicating widespread contamination sources. • • Detection primarily relies on GC-MS and LC-MS/MS, with methods achieving limits of quantification in the ng/L range for water samples, enabling trace-level monitoring essential for regulatory compliance. • • Treatment technologies include adsorption, photolysis, chemical oxidation, and biodegradation; however, degradation efficiencies vary widely, with photolysis and advanced oxidation processes showing potential for >90% removal under optimized conditions, but field-scale validation remains limited. • • The review identifies a critical research gap: lack of integrated, cost-effective treatment trains for DZP in fishery water, necessitating future work on combined technologies and real-world applicability.
Abstract
Diazepam (DZP), a benzodiazepine anxiolytic drug, has been a persistent contaminant in fishery water environments. In China, DZP is classified as a veterinary drug that must not be detected in animal-derived foods, yet it is frequently found in aquatic products, posing significant risks to ecological health and food safety. This review systematically summarizes the current pollution status of DZP in fishery water and its adverse effects on aquatic organisms, emphasizing its persistence in both water and aquatic products. The paper comprehensively examines advances in detection techniques, including gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), as well as treatment technologies such as adsorption, photolysis, chemical oxidation, and biodegradation. Critical gaps remain in the integration of these technologies for practical remediation. The review underscores the urgent need for enhanced monitoring and risk assessment of DZP contamination, alongside the development of more efficient and scalable treatment methods. By consolidating current knowledge, this work provides technical support for aquatic organism protection and fishery water management, and serves as a reference for future research and technological innovation in this field.
1. Introduction
Diazepam (DZP) contamination in fishery water environments has emerged as a persistent regulatory and ecological challenge. Despite its classification as a prohibited substance in animal food production in China, DZP is routinely detected in aquatic products, with contamination sources traced to illegal use in aquaculture and, notably, to recreational fishing practices where DZP is found in bait and feed additives. The physicochemical properties of DZP—low volatility, slight water solubility, and high organic solvent solubility—facilitate its environmental persistence and bioaccumulation, leading to chronic exposure risks for aquatic organisms and potential human health impacts through the food chain. Existing monitoring programs have incorporated DZP into national residue control plans, yet the lack of comprehensive treatment strategies hampers effective mitigation.
Current remediation approaches, including adsorption, photolysis, chemical oxidation, and biodegradation, have demonstrated variable efficacy under laboratory conditions, but their translation to field-scale applications is constrained by factors such as matrix complexity, cost, and secondary pollution. Moreover, the integration of detection and treatment technologies remains fragmented, with few studies offering a holistic framework for DZP management in fishery water. This review addresses this bottleneck by systematically consolidating the state-of-the-art in DZP pollution assessment and abatement, identifying critical knowledge gaps, and proposing future research directions. By providing a critical analysis of existing data, this work aims to inform the development of robust, economically viable, and environmentally sustainable treatment systems tailored to the unique challenges of fishery water environments.
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CHEN Xu, HUANG Dongmei, HUANG Xuanyun, SHI Yongfu, XU Yilin, LI Siman, YE Hongli (2026). Research Progress on the Pollution Status of Diazepam in Fishery Water Environment and Its Treatment Technology. Environmental Chemistry. https://doi.org/10.7524/j.issn.0254-6108.2025032401
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Frequently Asked Questions
What are the primary sources of diazepam contamination in fishery water, and how do they contribute to the persistence of DZP in aquatic products?
The primary sources include illegal use in aquaculture and, notably, contamination from recreational fishing activities, where DZP is found in bait, feed, and attractants. A survey of 23 regions found 14 out of 35 commercial fish bait products contained DZP, indicating widespread contamination. This external input, combined with DZP's low volatility and slight water solubility, leads to its persistence in water and bioaccumulation in aquatic organisms, resulting in frequent detection in aquatic products despite regulatory bans.
What are the current detection limits and analytical challenges for quantifying diazepam in complex fishery water matrices?
Detection typically employs GC-MS or LC-MS/MS, with methods achieving limits of quantification in the ng/L range for water samples. However, matrix effects from organic matter and salts can affect recovery and sensitivity. For instance, acidic transformation of nordiazepam can impact recovery estimates during trace analysis, necessitating careful sample preparation and internal standards. Advanced techniques like isotope dilution-UPLC-MS/MS have been developed for fish feed, achieving high accuracy and precision.
Which treatment technologies show the most promise for removing diazepam from fishery water, and what are their respective removal efficiencies and limitations?
Adsorption, photolysis, chemical oxidation, and biodegradation have been studied. Photolysis and advanced oxidation processes (e.g., UV/H2O2) can achieve >90% removal under optimized conditions, but efficiency depends on water quality parameters like turbidity and dissolved organic matter. Adsorption using activated carbon or biochar is effective but requires disposal of spent adsorbents. Biodegradation is slower and often incomplete. The review emphasizes the need for integrated approaches to overcome individual limitations.
What are the key research gaps and future directions for effective management of diazepam pollution in fishery water?
Key gaps include lack of field-scale validation of treatment technologies, limited understanding of DZP transformation products and their toxicity, and insufficient integration of monitoring with remediation strategies. Future research should focus on developing cost-effective, scalable treatment trains, enhancing degradation efficiency through combined methods, and establishing comprehensive risk assessment frameworks. Additionally, strengthening regulatory enforcement and promoting alternative fishing practices are critical to reduce DZP input.
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