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Improving our understanding of groundwater quality threats to human health and the environment is essential to protect and manage groundwater resources effectively. This essay highlights some global groundwater quality challenges, describes key contaminant groups and threats of emerging concern, including antimicrobial resistance, and discusses novel approaches to assessing groundwater quality. Groundwater quality monitoring needs to improve significantly in order to effectively identify and mitigate threats to groundwater from historical, current and future pollution.

Latest IPCC projections (2022) suggest significantly increased future incidence of infectious disease due to global warming and shifting climate patterns. Due to increasing global mean temperatures and extreme weather event frequency, assessing the potential impacts of climate change on infectious disease represents a critical challenge for public health authorities. This is particularly significant for environmentally-acquired infections which are directly or indirectly driven by local weather conditions. The current study sought to explore the relationship between antecedent weather and three gastrointestinal infections in the Republic of Ireland, namely cryptosporidiosis, Verotoxigenic E. Coli (VTEC) and campylobacteriosis.Irreversibly anonymised cases of infection were acquired from the national Computerised Infectious Disease Reporting (CIDR) database. Overall, 4,509 cases of cryptosporidiosis (2007 - 2017), 2,755 cases of VTEC enteritis (2013 - 2017) and 20,274 cases of campylobacteriosis (2011 - 2018) were employed. Individual cases were geographically linked to a Census Small Area (SA).Weekly seasonal adjustment of developed time series (trend & residuals of seasonally decomposed time-series) were undertaken for both climate and infection variables (incidence rate per 100k population). Climate variables were lagged from 1 to 20 weeks to account for likely delayed associations. A series of Spearman’s correlation matrices were subsequently developed. Infections hotspots were identified and used to construct space-time cluster frequency maps (Boudou et al., 2021, Cleary et al. 2021), with Monte-Carlo simulations used to simulate the effects of weekly mean temperature and rainfall changes on space-time cluster frequency. Analyses were delineated (restricted) based on season and settlement type (i.e., rural, urban, commuter areas).Spearman’s correlation matrices confirmed the presence of ranked associations between rainfall, temperature and all three infections. Weekly VTEC and campylobacteriosis incidence were positively associated with the non-lagged mean temperature (Rho >0.6). Maximum positive associations were obtained between non-lagged rainfall (mm) for VTEC (Rho=0.68) and campylobacteriosis (Rho= 0.6), while a delayed positive association was found for cryptosporidiosis with a maximum Rho of 0.21 (Week 19). Findings from Monte-Carlo simulation provided strong insights on the direct impacts of temperature and rainfall changes on infection cluster frequency. An increase of 1oC in weekly temperature was simulated to result in an 25% increase in the number of Small Areas reporting a space-time cluster of campylobacteriosis. Similarly, a 5mm increase in weekly rainfall was shown to increase the number of rural SAs reporting a space-time cluster of cryptosporidiosis by ≈4%.Study findings leave little doubt as to the significance of climate patterns for all three infections, with all shown to increase (incidence rates and/or cluster occurrence) in concurrence with increasing temperatures and rainfall volumes. Accordingly, there is a pressing need for development of adapted health strategies within the context of predicted climate change (i.e., increased testing/surveillance and treatment capacity, improved risk communication during extreme weather events,…). This result points out the need to promote multidisciplinary researches by including meteorologists, hydrologists and engineer in public health planning strategies.

While developed nations are assumed to provide high groundwater quality security, populations reliant on (typically rural, unregulated) private domestic groundwater wells are often uniquely vulnerable to supply contamination. The potential health ramifications of exposure to contaminated groundwater may be especially grave for immunosuppressed populations residing in service-deprived and climate-vulnerable areas, necessitating concerted government (educational) and household-level (behavioural) action. In response, a growing number of studies (spanning quantitative contamination risk assessments, policy strategies, communicative interventions and householder surveys) have emerged within the last several decades. To date, few investigations have sought to synthesise this literature and ascertain the potential generality of drivers of both private groundwater contamination and preventive responses in high-income countries. The developed regions of the Republic of Ireland (ROI) and Ontario represent an appropriate point of comparison to establish research transferability. Both regions are characterised by high private groundwater reliance (> 10% of their respective populations), pervasive microbial groundwater contamination and significant associations between acute gastrointestinal illness (AGI) and private well use. Consumption of private well water contributes to approximately 4,800 annual cases of AGI in Ontario and as many as 80% of annual cases of verotoxigenic E.coli (VTEC) in the ROI. However, despite similarities, regional discrepancies exist with respect to policy landscapes (e.g., monetary requirements for private water quality testing) and contamination risk profiles (e.g., frequency of extreme weather event concurrence). In efforts to elucidate the potential implications of these phenomena, a scoping review of literature (1990-2022) in the ROI and Ontario outlining risk management measures to prevent private groundwater contamination in the was undertaken. The SPICE (Setting, Population/Phenomenon, Intervention, Setting, Perspective) methodology was utilised to inform literature search terms, with Scopus and Web of Science selected as primary databases for article searches. Following removal of duplicate studies and article screening, 92 articles (Canada = 70, ROI = 22) were retained for analysis. Articles were predominantly comprised of quantitative contamination risk assessment studies (n = 68), with qualitative and quantitative questionnaire investigations (n = 16), interventions (n = 2) and policy studies (n = 6) noticeably less frequent. Quantitative risk assessments published after the year 2000 demonstrated an overwhelming focus on microbial supply contamination, identifying well type and proximity of agricultural activity as significant determinants of supply contamination. Survey studies in both regions also consistently highlighted gender, perceived confidence in maintaining supply and economic and convenience barriers as significant determinants of well user knowledge and behaviour. However, well users in Ontario demonstrated markedly higher rates of prior well testing (irrespective of adherence to regional guidelines), suggesting that incentivised (or free) well testing may lead to significant increases in uptake of well water quality testing. The paucity of identified intervention studies suggests that increased research investigating methods of well user outreach and groundwater risk communication will be necessary in the future to determine the broad efficacy of risk communication in developed nations.

Antimicrobial-resistant Escherichia coli isolates have emerged in various ecologic compartments and evolved to spread globally. We sought to (1.) investigate the occurrence of ESBL-producing E. coli (ESBL-Ec) in feces from free-range chickens in a rural region and (2.) characterize the genetic background of antimicrobial resistance and the genetic relatedness of collected isolates. Ninety-five feces swabs from free-range chickens associated with two households (House 1/House 2) in a rural region in northern Tunisia were collected. Samples were screened to recover ESBL-Ec, and collected isolates were characterized for phenotype/genotype of antimicrobial resistance, integrons, and molecular typing (pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST)). Overall, 47 ESBL-Ec were identified, with the following genes detected: 35 blaCTX-M-1, 5 blaCTX-M-55, 5 blaCTX-M-15, 1 blaSHV-2, and 1 blaSHV-12. Resistance to fluoroquinolones, tetracycline, sulfonamides, and colistin was encoded by aac(6′)-Ib-cr (n = 21), qnrB (n = 1), and qnrS (n = 2); tetA (n = 17)/tetB (n = 26); sul1 (n = 29)/sul2 (n = 18); and mcr-2 (n = 2) genes, respectively. PFGE and MLST identified genetic homogeneity of isolates in House 1; however, isolates from House 2 were heterogeneous. Notably, among nine identified sequence types, ST58, ST69, ST224, and ST410 belong to pandemic high-risk clonal lineages associated with extrapathogenic E. coli. Minor clones belonging to ST410 and ST471 were shared by chickens from both households. The virulence genes fyuA, fimH, papGIII, and iutA were detected in 35, 47, 17, and 23 isolates, respectively. Findings indicate a high occurrence of ESBL-Ec in free-range chickens and highlight the occurrence of pandemic zoonotic clones.

This systematic literature review aimed to provide an overview of the characteristics and methods used in studies applying the Disability-Adjusted Life Years (DALY) concept for infectious diseases within European Union (EU)/European Economic Area (EEA)/European Free Trade Association (EFTA) countries and the United Kingdom. Electronic databases and grey literature were searched for articles reporting the assessment of DALY and its components. We considered studies in which researchers performed DALY calculations using primary epidemiological data input sources. We screened 3,053 studies of which 2,948 were excluded and 105 studies met our inclusion criteria. Of these studies, 22 were multi-country and 83 were single-country studies, of which 46 were from the Netherlands. Food- and water-borne diseases were the most frequently studied infectious diseases. Between 2015 and 2022, the number of burden of infectious disease studies was 1.6 times higher compared to that published between 2000 and 2014. Almost all studies (97%) estimated DALYs based on the incidence- and pathogen-based approach and without social weighting functions; however, there was less methodological consensus with regards to the disability weights and life tables that were applied. The number of burden of infectious disease studies undertaken across Europe has increased over time. Development and use of guidelines will promote performing burden of infectious disease studies and facilitate comparability of the results., peer-reviewed

Milk and beef derived from pasture-based systems have been characterized by higher nutritional values and a lower environmental footprint than their equivalents obtained via indoor systems. However, intensification of pasture-based production can have adverse impacts on biodiversity and the environment. To date, studies on pro-environmental diversification options leading to improvement of environmental performance of pasture-based dairy and beef production have rarely been synthesized. The present study sought to review current on-farm pro-environmental measures with the potential for enhancing biodiversity status and/or reducing the environmental impacts of pasture-based agriculture. Literature on farmer attitudes toward these measures was also reviewed to identify potential obstacles and opportunities for transitioning to pro-environmental agriculture. A systematic search of published research from high-income island countries characterized by oceanic temperate climate with a high dependence on pasture-based agriculture—the Republic of Ireland, the United Kingdom and New Zealand, was conducted. Thirty studies that assessed the impact of pro-environmental measures, eight ‘attitudinal’ studies of dairy and beef farmers and one study covering both aspects were identified. Inductive thematical analysis was subsequently undertaken. Environmentally sensitive management practices such as hedgerows and field margins management, mixed grazing (where two or more herbivorous animals graze the same land), rare livestock breeds, multispecies swards, organic farming and agroforestry were identified as primary themes studied under the auspices of pro-environmental diversification, while forestry, bioenergy crops and organic farming were the main themes identified within attitudinal research studies. Findings suggest that environmentally sensitive practices have varied effects on biodiversity. Mixed grazing was found to improve livestock production, while studies of organic farming reported multiple positive impacts on biodiversity and animal welfare. Effect of multispecies swards on methane emissions and urinary nitrogen extraction were found to be inconsistent. Attitudinal research suggests that the main barrier to implementing afforestation is its lack of attractiveness compared to ‘traditional’ farming and that organic farmer decisions regarding agricultural management practices might be less profit-oriented and influenced by ecological beliefs to a greater extent than decisions of conventional farmers. The results of this study confirm that pro-environmental diversification inherently encompasses multiple scientific disciplines; however, previous study designs and outcomes were found to be fragmented and narrowly focused. Considering the urgency and importance of climate and biodiversity crises, pro-environmental diversification of pasture-based dairy and beef production has rarely been holistically approached and remains understudied. The development of practical, sustainable solutions for farming based on circular economy and respect to nature and additional strategies to increase farmer and consumer environmental awareness should be prioritized by policymakers, advisory and scientific bodies.

The role of the natural environment in the dissemination of antimicrobial resistant bacteria has been increasingly recognised in the literature. However, knowledge surrounding the critical factors and mechanisms mediating their occurrence is still limited, particularly in relatively 'pristine' groundwater environments. In the Republic of Ireland (RoI), a country characterised by high groundwater reliance, household-based (unregulated) wells provide drinking water to 11% of the population. These private wells are generally located in rural areas, where the risk of microbiological contamination is high due to intensive agricultural practices and high reliance on domestic wastewater treatment systems; both of which are also potential sources of antimicrobials and antimicrobial resistant bacteria. Accordingly, the current research sought to elucidate current rates of antimicrobial resistant bacteria and the principal factors associated with their presence in private wells in the RoI. A total of 250 samples (from 132 wells nationwide) were assessed for the presence of faecal (Escherichia coli) and environmental (Pseudomonas aeruginosa) bacteria, with single isolates from each contaminated sample tested phenotypically against 18 and 9 antimicrobials, respectively. Findings show that while 16.7% of E. coli (n = 8/48) were categorically resistant to ≥1 antimicrobial, with a further 79.2% classified as intermediately resistant, no categorical resistance was found among P. aeruginosa isolates (n = 0/6), with just one intermediately resistant isolate detected. Multivariate regression modelling indicates significantly higher odds of resistant E. coli detection in concurrence with elevated cattle density (OR = 1.028, p = 0.032), aligning with findings of highest resistance rates to veterinary antimicrobials (e.g., streptomycin = 14.6%, tetracycline = 12.5%, and ampicillin = 12.5%). Multivariate model results also suggest overland flow culminating in direct wellhead ingress as a primary ingress mechanism for resistant E. coli. Study findings may inform groundwater source protection initiatives and antimicrobial resistance surveillance moving forward.

Over recent years, Ireland has reported the highest crude incidence rates of Shiga toxin-producing Escherichia coli (STEC) enteritis in Europe. Unregulated private groundwater sources have emerged as an important potential transmission route for STEC, with up to 750,000 Irish residents reliant on these sources for domestic waters. This study aimed to investigate the prevalence and serogroup profile of STEC contamination from domestic private wells in western Ireland. Fifty-two groundwater sources were analysed during two sampling campaigns in the autumn (September/October) of 2019 (n = 21) and 2021 (n = 31). Untreated groundwater samples (30 L) were collected and analysed using the "CapE" (capture, amplify, extract) method. Extracted DNA was tested using multiplex real-time PCR for Shiga toxin stx1 and/or stx2 and eae genes. STEC positive DNA samples were tested for clinically relevant serogroups by real-time PCR. Data relating to 27 potential groundwater contamination risk factors were geospatially linked to each well and assessed for association with E. coli, stx1 and/or stx2 and eae presence/absence. Overall, 20/52 wells (38.4 %) were positive for E. coli (median concentration 8.5 MPN/100 mL as assessed by Colilert-18 method). Stx1 and/or stx2 was detected in 10/52 (19.2 %) wells overall and 8/20 E. coli positive wells, equating to a STEC to "generic" E. coli detection ratio of 40 %. Six of these wells (30 %) were also positive for eae. One or more serogroup-specific gene targets were identified in all but one stx1 and/or stx2 positive sample, with O145 (n = 6), O157 (n = 5) and O103 (n = 4) most prevalent. STEC presence was significantly associated with decreasing well depth (U = -2.243; p = 0.024) and increasing 30-day mean antecedent rainfall (U = 2.126; p = 0.034). Serogroup O104 was associated with increased sheep density (U = 2.089; p = 0.044) and detection of stx1 and/or stx2 + eae with increased septic tank density (U = 2.246 p = 0.023). Findings indicate high detection rates of clinically relevant STEC in E. coli contaminated groundwater sources in Ireland.

Antimicrobial resistance represents a global health problem, with infections due to pathogenic antimicrobial resistant bacteria (ARB) predicted to be the most frequent cause of human mortality by 2050. The phenomenon of antimicrobial resistance has spread to and across all ecological niches, and particularly in livestock used for food production with antimicrobials consumed in high volumes. Similarly, hospitals and other healthcare facilities are recognized as significant ‘hotspots’ of ARB and antimicrobial resistance genes (ARGs); however, over the past decade, new and previously overlooked ecological niches are emerging as hidden reservoirs of ARB/ARGs. Increasingly extensive and intensive industrial activities, degradation of natural environments, burgeoning food requirements, urbanization, and global climatic change have all dramatically affected the evolution and proliferation of ARB/ARGs, which now stand at extremely concerning ecological levels. While antimicrobial resistant bacteria and genes as they originate and emanate from livestock and human hosts have been extensively studied over the past 30 years, numerous ecological niches have received considerably less attention. In the current descriptive review, the authors have sought to highlight the importance of wildlife as sources/reservoirs, pathways and receptors of ARB/ARGs in the environment, thus paving the way for future primary research in these areas.

Available evidence indicates Extreme Weather Event (EWE) frequency has increased significantly in the last ⁓ 70 years along a 0.5°C global temperature rise. As such, a major concern arising from global warming projections are the potential impacts of increasingly frequent and intense EWEs on public health and societal well-being. The substantial toll of EWEs on socio-economic and physical health is well understood. Yet, due to a range of methodological impediments, the impact EWEs on psychological health and well-being remain less certain. Within this context, this literature review aimed to provide an “empirical” baseline of the psychological and well-being impacts of individuals exclusively exposed to EWEs. Given the wide range of psychological and well-being metrics available in the literature, the review was grounded on a ‘holistic’ approach with the all-encompassing concept of “psychological impairment” adopted. Here, impairment data, or morbidity, was pooled at the level of key Diagnostic and Statistical Manual of Mental Disorders (DSM) psychological “Domains”, including PTSD, Anxiety and Depression. Morbidity data was also pooled at a “composite” (any impairment) category encompassing all employed DSM-based domains. Further, reported risk factors (p < 0.05) and pooled odds ratios (pOR) were extracted and calculated from each pertinent study. Overall, 59 peer-reviewed investigations accounting for 61,443 EWE-exposed individuals comprised the review dataset. A “composite” post-exposure pooled-prevalence rate of 23% was estimated along with values of 24% for depression and ⁓ 17% for both PTSD and anxiety. Notably, estimated pOR (1.9) indicate a > 90% likelihood of a negative psychological outcome or impaired well-being among exposed individuals. Methodologically, a prevalent lack of integration of “control” criterion among reviewed investigations was identified. In this context, pooled data collated can be considered more akin to “prevalence” rates rather than a finite metric of “incidence” linking EWE exposure and outcomes. Collation of reported risk factors indicate more pronounced impacts among individuals with higher levels of EWE exposure (14.5%) and socio-demographic traits which are often associated with vulnerable population sub-groups, including female gender (10%), lower socio-economic status (5.5%), and a lower education level (5.2%). Regionally, Asia exhibited the highest impairment rates which is tentatively attributed to a combination of high EWE frequency and population density. The findings of this study provide a quantitative evidence base which can be used to inform public health intervention strategies focusing on exposed populations in the aftermath of EWEs.

A spatiotemporally static total coliform (TC) concentration threshold of five colony-forming units (CFU) per 100 mL is used in Ontario to determine whether well water is of acceptable quality for drinking. The current study sought to assess the role of TC and associated thresholds as microbial water quality parameters as the authors hypothesized that, since static TC thresholds are not evidence-based, they may not be appropriate for all well water consumers. A dataset containing the microbial water quality information of 795,023 samples (including TC and Escherichia coli (E. coli) counts) collected from 253,136 private wells in Ontario between 2010 and 2017 was used. To accurately assess the relationship between E. coli and non-E. coli TC, "non-E. coli coliform" (NEC) counts were calculated from microbial water quality data and replaced TC throughout analyses. This study analysed NEC and E. coli detection rates to determine differences between the two, and NEC:E. coli concentration ratios to assess links, if any, between NEC and E. coli contamination. Study findings suggest that spatiotemporally static NEC thresholds are not appropriate because seasonal, spatial, and well-specific susceptibility factors are associated with distinct contamination trends. For example, NEC detection rates exhibited bimodality, with summer (29.4 %) and autumn (30.2 %) detection rates being significantly higher (p0.05) than winter (21.9 %) and spring (19.9 %). E. coli detection rates also varied seasonally, but peaked in summer rather than autumn. As such, it is recommended that these factors be considered during the development of private well water guidelines and that static thresholds be avoided. Furthermore, the authors propose that, because NEC:E. coli concentration ratios change in the context of the aforementioned factors, they may have a role in inferring groundwater contamination mechanisms, with high ratios being associated with generalized aquifer contamination mechanisms and low ratios with localized contamination mechanisms.