An integrated approach to MS-based identification and risk assessment of pharmaceutical biotransformation in wastewater

Combining predictive and analytical methods to elucidate pharmaceutical biotransformation in activated sludge

While man-made chemicals in the environment are ubiquitous and a potential threat to human health and ecosystem integrity, the environmental fate of chemical contaminants such as pharmaceuticals is often poorly understood. Biodegradation processes driven by microbial communities convert chemicals into transformation products (TPs) that may themselves have adverse ecological effects. The detection of TPs formed during biodegradation has been continuously improved thanks to the development of TP prediction algorithms and analytical workflows. Here, we contribute to this advance by (i) reviewing past applications of TP identification workflows, (ii) applying an updated workflow for TP prediction to 42 pharmaceuticals in biodegradation experiments with activated sludge, and (iii) benchmarking 5 different pathway prediction models, comprising 4 prediction models trained on different datasets provided by enviPath, and the state-of-the-art EAWAG pathway prediction system. Using the updated workflow, we could tentatively identify 79 transformation products for 31 pharmaceutical compounds. Compared to previous works, we have further automatized several steps that were previously performed by hand. By benchmarking the enviPath prediction system on experimental data, we demonstrate the usefulness of the pathway prediction tool to generate suspect lists for screening, and we propose new avenues to improve their accuracy. Moreover, we provide a well-documented workflow that can be (i) readily applied to detect transformation products in activated sludge and (ii) potentially extended to other environmental studies.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

Hypoxia aggravates the burden of yellowstripe goby (Mugilogobius chulae) under atorvastatin exposure

In the present study, an estuarine benthic fish, Mugilogobius chulae (M. chulae), was exposed to hypoxia, atorvastatin (ATV), a highly used and widely detected lipid-lowering drug in aquatic environment, and the combination of hypoxia and ATV for 7 days, respectively, so as to address and compare the effects of the combination of hypoxia and ATV exposure on M. chulae. The results showed that lipid metabolism in M. chulae was greatly affected: lipid synthesis was blocked and catabolism was enhanced, exhibiting that lipids content were heavily depleted. The combined exposure of hypoxia and ATV caused oxidative stress and induced massive inflammatory response in the liver of M. chulae. Signaling pathways involving in energy metabolism and redox responses regulated by key factors such as HIF, PPAR, p53 and sirt1 play important regulatory roles in hypoxia-ATV stress. Critically, we found that the response of M. chulae to ATV was more sensitive under hypoxia than normoxia. ATV exposure to aquatic non-target organisms under hypoxic conditions may make a great impact on the detoxification and energy metabolism, especially lipid metabolism, and aggravate the oxidative pressure of the exposed organisms.

Identification and monitoring of fentanyls-related substances in east China sewage water samples by LC-MS for drug enforcement

Fentanyls abuse is a persistent international concern. New fentanyl derivatives are constantly appearing, circumventing national and international laws. In this study, laboratory degradation experiment with different conditions such as pH, light, temperature and oxygen availability were compared to improve the understanding of the fentanyls degradation pathways. Twelve major degradants of sufentanil and alfentanil were detected and identified together using UHPLC-QTOF-MS. A total of thirty nine fentanyls including twelve typical fentanyl new psychoactive substances, eighteen manufacturing process-related substances and nine key degradants of sufentanil and alfentanil were screened in 120 sewage water samples collected from 20 sewage water treatment plants chosen among 6 urban cities in east China from July to August in 2020 using a validated UHPLC-MS/MS method. Three fentanyls (fentanyl, sufentanil, alfentanil), seven degradants and six manufacturing process-related substances were found in the test samples. The study could provide a useful tool for the monitoring of the abuses, illegal manufacturing or pharmaceuticals related pollutions of fentanyls and their analogs.