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Persistent organic pollutants (POPs) accumulate in the food web of the Great Lakes ecosystem, causing concern that these chemicals play a role in the decline of avian species such as colonial-nesting waterbirds. In this study, samples from four life stages of the common tern (Sterna hirundo), a threatened species in New York State, were collected post-mortem in the Buffalo-Niagara region (United States). Brains (n = 26) and livers (n =27) were analyzed for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and the insecticide p,p’-dichlorodiphenyltrichloroethane (DDT) and its two metabolites p,p’-dichlorodiphenyldichloroethylene (DDE) and p,p’-dichlorodiphenyldichloroethane (DDD). Detectable concentrations of PCBs and PBDEs were observed in all samples; concentrations of total PCBs ranged from 5.59 to 2,490 ng/g wet weight (ww), total PBDEs ranged from 1.09 to 494 ng/g ww, and DDE metabolites ranged from 0.56 to 637 ng/g ww. Analysis of the primary food source for terns in the Buffalo-Niagara region, emerald shiners (Notropis atherinoides), revealed that all three classes of POPs had similar contaminant profiles in the fish to those in the brains and livers of tern samples. Overall, small chicks contained greater concentrations of pollutants than medium chicks and juveniles, likely from maternal loading to eggs. These results underline the persistence of these legacy contaminants in the Great Lakes, despite their banning, and their biomagnification in threatened species through food web interactions.

Background: Antimicrobial resistance (AMR) is a growing public health concern. Recent research has suggested that interactions between pathogens and antibiotic residues in various environmental matrices promote the development and spread of AMR in the environment. The levels of antibiotic residues in the aquatic environment have been analysed globally. Recently, Predicted No Effect Environmental Concentration (PNEC) values for many antibiotics have been suggested, based on their estimated minimal selective concentrations for selected bacterial species. The PNEC values can serve as a guide on the maximum levels of antibiotic residues in an environmental matrix, below which resistance is unlikely to develop. Aim: We aimed to determine which of the antibiotics, considered as “priority antibiotics” by the World Health Organisation (WHO), most frequently exceeded their PNEC values in the global aquatic environment. Methods: We obtained data from the German Environment Agency pharmaceutical database on means, medians or single values of 12 antibiotic types in five different environmental matrices [municipal wastewater treatment plant effluent, industrial wastewater effluent, hospital wastewater effluent, surface water, and drinking water] across 47 countries. We compared the mean levels of the 12 antibiotics in each environmental matrix to their suggested PNEC values to determine which antibiotic types exceeded PNEC and were most likely to select for resistance. We also determined which environmental matrices and countries had the highest burden of antibiotic residues. Results: Our study revealed that 7.9% of all analyses of antibiotic residues performed in the environmental matrices globally exceeded PNEC. Ciprofloxacin and clarithromycin had the greatest proportion (>30%) of residues exceeding PNEC. Hospital wastewater and industrial wastewater had the highest burden of antibiotic residues exceeding PNEC. No antibiotics exceeded PNEC in drinking water. Conclusion: While most environmental monitoring studies have focused on municipal wastewater treatment plants, the limited number of studies on hospital wastewater and industrial wastewater revealed that a large number of antibiotic residues coming from these sources exceeded their PNEC values. Our study highlights the importance of implementing on-site treatment systems that aim to destroy antibiotics prior to discharging wastewater to surface waters. Attention needs to be focused on the role that environmental matrices, particularly our wastewater sites, play in promoting antibiotic resistance. Novel treatment technologies need to be developed and implemented to increase the removal efficiencies of treatment plants and from antibiotic manufacturing, and decrease the discharge of antibiotic residues into aquatic environments.

Antimicrobial resistance is a worldwide problem that is both pressing and challenging due to the rate at which it is spreading, and the lack of understanding of the mechanisms that link human, animal and environmental sources contributing to its proliferation. One knowledge gap that requires immediate attention is the significance of antimicrobial residues and other pharmaceuticals that are being discharged from wastewater treatment plants (WWTPs) on the dissemination of antimicrobial resistance in the environment. In this work we provide an approach to develop a harmonized analytical method for 8 classes of antimicrobials and other pharmaceuticals that can be used for global monitoring in wastewater and receiving waters. Analysis of these trace organic chemicals in the influent and effluent wastewater, and in the respective upstream and downstream receiving waters from different countries across the globe is not trivial. Here, we demonstrated that sample preparation using solid-phase extraction (SPE) not only provides a convenient and cost-effective shipping of samples, but also adds stability to the analytes during international shipping. It is important that SPE cartridges are maintained at cold temperature during shipment if the duration is longer than 7 days because a significant decrease in recoveries were observed after 7 days in the cartridges stored at room temperature, especially for sulfonamides and tetracyclines. To compensate for sample degradation during shipment, and matrix effects in liquid chromatography/mass spectrometry, the use of stable isotope labeled compounds should be employed when available and affordable. The importance of applying a defined tolerance for the ion ratios (Q/q) that have been optimized for wastewater and surface water is discussed. The tolerance range was set to be the mean Q/q of the analyte standard at various concentrations ±40% for the influent, and ±30% for the effluent, upstream, and downstream samples; for tetracyclines and quinolones, however, the tolerance range was ±80% in order to minimize false negative and false positive detection. The optimized procedures were employed to reveal differences in antimicrobial and pharmaceutical concentrations in influent, effluent, and surface water samples from Hong Kong, India, Philippines, Sweden, Switzerland, and United States. The antimicrobials with the highest concentrations in influent and effluent samples were ciprofloxacin (48,103 ng/L, Hong Kong WWTP 1) and clarithromycin (5178 ng/L, India WWTP 2), respectively. On the other hand, diclofenac (108,000 ng/L, Sweden WWTP 2), caffeine (67,000 ng/L, India WWTP 1), and acetaminophen (28,000 ng/L, India WWTP 1) were the highest detected pharmaceuticals in the receiving surface water samples. Hong Kong showed the highest total antimicrobial concentrations that included macrolides, quinolones, and sulfonamides with concentrations reaching 60,000 ng/L levels in the influent. Antidepressants were predominant in Sweden, Switzerland, and the United States. Keywords: Antibiotics, Antimicrobial resistance, Antidepressants, Wastewater, Global analysis, LC-MS/MS