Many types of contaminants of emerging concern (CECs), including per- and poly-fluoroalkyl substances (PFAS), have been found in leachate of operating municipal landfills. However, there is only limited information on CECs presence in leachate of historic landfills (≥3 decades since closure, often lacking engineered liners or leachate collection systems) at concentrations that may pose a risk to nearby wells and surface water ecosystems. In this study, 48 samples of leachate-impacted groundwater were collected from 20 historic landfills in Ontario, Canada. The CECs measured included artificial sweeteners (ASs), PFAS, organophosphate esters (OPE), pharmaceuticals, bisphenols, sulfamic acid, perchlorate, and substituted phenols. The common presence of the AS saccharin, a known indicator of old landfill leachate, combined with mostly negligible levels of the AS acesulfame, an indicator of modern wastewater, revealed that most samples were strongly influenced by leachate and not cross-contaminated by wastewater (which can contain these same CECs). Several landfills, including ones closed in the 1960s, had total PFAS concentrations similar to those previously measured at modern landfills, with a maximum observed here of 12.7 μg/L. Notably elevated concentrations of several OPE, sulfamic acid, cotinine, and bisphenols A and S were found at many 30-60 year-old landfills. There was little indication of declining concentrations with landfill age, suggesting historic landfills can be long-term sources of CECs to groundwater and that certain CECs may be useful tracers for historic landfill leachate. These findings provide guidance on which CECs may require monitoring at historic landfill sites and wastewater treatment plants receiving their effluent.

Pollution by chemical substances is of concern for the maintenance of healthy and sustainable aquatic environments. While the occurrence and fate of numerous emerging contaminants, especially pharmaceuticals, is well documented in freshwater, their occurrence and behavior in coastal and marine waters is much less studied and understood. This study investigates the occurrence of 58 chemicals in the open surface water of the Western Mediterranean Sea for the first time. 70 samples in total were collected in 10 different sampling areas. 3 pesticides, 11 pharmaceuticals and personal care products and 2 artificial sweeteners were detected at sub-ng to ng/L levels. Among them, the herbicide terbuthylazine, the pharmaceuticals caffeine, carbamazepine, naproxen and paracetamol, the antibiotic sulfamethoxazole, the antibacterial triclocarban and the two artificial sweeteners acesulfame and saccharin were detected in all samples. The compound detected at the highest concentration was saccharin (up to 5.23 ng/L). Generally small spatial differences among individual sampling areas point to a diffuse character of sources which are likely dominated by WWTP effluents and runoffs from agricultural areas or even, at least for pharmaceuticals and artificial food additives, from offshore sources such as ferries and cruising ships. The implications of the ubiquitous presence in the open sea of chemicals that are bio-active or toxic at low doses on photosynthetic organisms and/or bacteria (i.e., terbuthylazine, sulfamethoxazole or triclocarban) deserve scientific attention, especially concerning possible subtle impacts from chronic exposure of pelagic microorganisms.

Artificial sweeteners are gaining acceptance as tracers of human wastewater in the environment. The 3 artificial sweeteners analyzed in this study were detected in leachate or leachate-impacted groundwater at levels comparable to those of untreated wastewater at 14 of 15 municipal landfill sites tested, including several closed for >50 years. Saccharin was the dominant sweetener in old (pre-1990) landfills, while newer landfills were dominated by saccharin and acesulfame (introduced 2 decades ago; dominant in wastewater). Cyclamate was also detected, but less frequently. A case study at one site illustrates the use of artificial sweeteners to identify a landfill-impacted groundwater plume discharging to a stream. The study results suggest that artificial sweeteners can be useful tracers for current and legacy landfill contamination, with relative abundances of the sweeteners potentially providing diagnostic ability to distinguish different landfills or landfill cells, including crude age-dating, and to distinguish landfill and wastewater sources.

This is the first comprehensive study on the input, occurrence, and distribution of artificial sweeteners (ASs) in coastal wastewater treatment plants (WWTPs) and their receiving coastal waters. Acesulfame (ACE), aspartame (ASP), cyclamate (CYC), saccharine (SAC), and sucralose (SUC) were monitored for 6 months in Cadiz Bay (SW Spain). ASP was always detected at <0.1 μg L−1 and removal efficiencies were >90% for SAC and CYC. Higher ACE removal efficiencies were observed during warmer months. Persistence of ACE and SUC was observed in both WWTPs and their receiving coastal surface waters, where values up to 0.6 and 3 μg L−1 were measured, respectively. The highest concentrations were measured in a sewage-impacted estuary located in the north of the bay, where conservative behavior was confirmed. The source specificity and recalcitrance of ACE and SUC make them suitable for being used as sewage-pollution markers in coastal environments.

Low-calorie sweeteners are widespread. They are routinely introduced into commonly consumed food such as diet sodas, cereals, and sugar-free desserts. Recent data revealed the presence in considerable quantities of some of these artificial sweeteners in water samples qualifying them as a class of potential new emerging contaminants. This study aimed at evaluating the ecotoxicity profile of MNEI and Y65R-MNEI, two engineered products derived from the natural protein monellin, employing representative test organism such as Daphnia magna, Ceriodaphnia dubia, and Raphidocelis subcapitata. Potential genotoxicity and mutagenicity effects on Salmonella typhimurium (strain TA97a, TA98, TA100, and TA1535) and Escherichia coli (strain WP2 pkM101) were evaluated. No genotoxicity effects were detected, whereas slight mutagenicity was highlighted by TA98 S. typhimurium. Ecotoxicity results evidenced effects approximately up to 14 and 20% with microalgae at 500 mg/L of MNEI and Y65R-MNEI, in that order. Macrophytes and crustaceans showed no significant effects. No median effective concentrations were determined. Overall, MNEI and Y65R-MNEI can be classified as not acutely toxic for the environment.