Estimating the duration and overlap of Escherichia coli contamination events in private groundwater supplies for quantitative risk assessment using a multiannual (2010-2017) provincial dataset

Private groundwater contamination and risk management: A comparative scoping review of similarities, drivers and challenges across two socio-economically developed regions

Consolidation of multi-domain risk management research is essential for strategies facilitating the concerted government (educational) and population-level (behavioural) actions required to reduce microbial private groundwater contamination. However, few studies to date have synthesised this literature or sought to ascertain the causal generality and extent of supply contamination and preventive responses. In light of the Republic of Ireland (ROI) and Ontario's high reliance and research focus on private wells and consequent utility for empirical comparison, a scoping review of pertinent literature (1990-2022) from both regions was undertaken. The SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) method was employed to inform literature searches, with Scopus and Web of Science selected as primary databases for article identification. The review identified 65 relevant articles (Ontario = 34, ROI = 31), with those investigating well user actions (n = 22) and groundwater quality (n = 28) the most frequent. A markedly higher pooled proportion of private supplies in the ROI exhibited microbial contamination (38.3 % vs. 4.1 %), despite interregional similarities in contamination drivers (e.g., weather, physical supply characteristics). While Ontarian well users demonstrated higher rates of historical (≥ 1) and annual well testing (90.6 % vs. 71.1 %; 39.1 % vs. 8.6 %) and higher rates of historical well treatment (42.3 % vs. 24.3 %), interregional levels of general supply knowledge were analogous (70.7 % vs. 71.0 %). Financial cost, organoleptic properties and residence on property during supply construction emerged as predictors of cognition and behaviour in both regions. Review findings suggest broad interregional similarities in drivers of supply contamination and individual-level risk mitigation, indicating that divergence in contamination rates may be attributable to policy discrepancies - particularly well testing incentivisation. The paucity of identified intervention-oriented studies further highlights the importance of renewed research and policy agendas for improved, targeted well user outreach and incentivised, convenience-based services promoting routine supply maintenance.

Application of conventional and emerging low-cost adsorbents as sustainable materials for removal of contaminants from water

The impact of water pollution has led to the search for cost-effective and environmentally friendly treatment processes to alleviate the associated environmental hazards. Adsorption is identified as an advanced treatment technology that offers simplicity and cheap alternatives to water treatment technologies when low-cost adsorbents such as industrial by-products, waste, and agricultural waste are utilized. The utilization of these materials as low-cost adsorbents for the treatment of drinking water will bring them some value. Several practices have been done to improve the removal efficiencies of the low-cost adsorbents in order to achieve WHO standards of drinking water quality. The paper highlights some of the synthesis routes employed for the modification of low-cost adsorbents. This updated review provides information on the different applications of low-cost adsorbents in removing pollutants and their adsorption capacities in an attempt to deploy the recent sustainable low-cost adsorbents with high removal efficiencies for water treatment. Future research should focus on the fabrication of hybrid low-cost adsorbents with multifunctional and antimicrobial properties. In addition, life cycle assessment (LCA) should be conducted to reveal the environmental burdens associated with the modification of the low-cost adsorbent to improve their removal efficiencies.

Integrating consumer risk perception and awareness with simulation-based quantitative microbial risk assessment using a coupled systems framework: A case study of private groundwater users in Ontario

Private well users in Ontario are responsible for ensuring the potability of their own private drinking water source through protective actions (i.e., water treatment, well maintenance, and regular water quality testing). In the absence of regulation and limited surveillance, quantitative microbial risk assessment (QMRA) represents the most practical and robust approach to estimating the human health burden attributable to private wells. For an increasingly accurate estimation, QMRA of private well water should be represented by a coupled model, which includes both the socio-cognitive and physical aspects of private well water contamination and microbial exposure. The objective of the current study was to determine levels of waterborne exposure via well water consumption among three sub-groups (i.e., clusters) of private well users in Ontario and quantify the risk of waterborne acute gastrointestinal illness (AGI) attributed to Giardia, shiga-toxin producing E. coli (STEC) and norovirus from private drinking water sources in Ontario. Baseline simulations were utilized to explore the effect of varying socio-cognitive scenarios on model inputs (i.e., increased awareness, protective actions, aging population). The current study uses a large spatio-temporal groundwater quality dataset and cross-sectional province-wide survey to create socio-cognitive-specific QMRA simulations to estimate the risk of waterborne AGI attributed to three enteric pathogens in private drinking waters source in Ontario. Findings suggest significant differences in the level of exposure among sub-groups of private well users. Private well users within Cluster 3 are characterised by higher levels of exposure and annual illness attributable to STEC, Giardia and norovirus than Clusters 1 and 2. Provincial incidence rates of 520.9 (1522 illness per year), 532.1 (2211 illness per year) and 605.5 (5345 illness per year) cases/100,000 private well users per year were predicted for private well users associated with Clusters 1 through 3. Established models will enable development of necessary tools tailored to specific groups of at-risk well users, allowing for preventative public health management of private groundwater sources.

Assessing the risk of acute gastrointestinal illness attributable to three enteric pathogens from contaminated private water wells in Ontario

The province of Ontario compromises the largest groundwater reliant population in Canada serving approximately 1.6 million individuals. Unlike municipal water systems, private well water is not required to meet water quality regulatory standards and thus source maintenance, treatment and testing remains the responsibility of the well owner. Infections associated with private drinking water systems are rarely documented given their typically sporadic nature, thus the human health effects (e.g., acute gastrointestinal illness (AGI)) on consumers remains relatively unknown, representing a significant gap in water safety management. The current study sought to quantify the risk of waterborne AGI attributed to Giardia, shiga-toxin producing E. coli (STEC) and norovirus from private drinking water sources in Ontario using Monte Carlo simulation-based quantitative microbial risk assessment (QMRA). Findings suggest that consumption of contaminated private well water in Ontario is responsible for approximately 4823 AGI cases annually, with 3464 (71.8%) and 1359 (28.1%) AGI cases predicted to occur in consolidated and unconsolidated aquifers, respectively. By pathogen, waterborne AGI was attributed to norovirus (62%; 2991/4823), Giardia (24.6%; 1186/4823) and STEC (13.4%; 646/4823). The developed QMRA framework was used to assess the potential health impacts of partial and total well water treatment system failure. In the unlikely event of total treatment failure, total mean annual illnesses are predicted to almost double (4217 to 7064 cases per year), highlighting the importance of effective water treatment and comprehensive testing programs in reducing infectious health risks attributable to private well water in Ontario. Study findings indicate significant underreporting of waterborne AGI rates at the provincial level likely biasing public health interventions and programs that are effective in monitoring and minimizing the health risk associated with private well water.