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.

An outbreak investigation of acute Diarrheal Disease, Nagpur District, Maharashtra, India.

BACKGROUND: Acute diarrheal disease (ADD) accounts for 12 million cases and 1216 deaths annually in India. On July 13, 2016, an ADD outbreak was reported from Sawargaon village from Nagpur district, Maharashtra. OBJECTIVE: The outbreak was investigated to describe the epidemiology and suggest control and preventive measures. METHODS: A case was defined as a person experiencing at least one loose stool in Sawargaon village between July 9, 2016, and July 31, 2016. We searched for cases by enhanced passive surveillance. We collected stool samples for bacterial culture and tested water from multiple water sources for fecal coliforms. We also reviewed sanitary practices and rainfall data. RESULTS: A total of 889 cases were identified, with 51% female, 280 hospitalizations (31%), and two deaths. The median age was 27 years (range 6 months to 90 years). Cases started on July 9, a week after heavy rains. District authorities started chlorination of water sources on July 13 and cases declined soon after. Two of nine stool samples tested positive for Vibrio cholera O1 serogroup. Of the 18 water samples collected, 16 (88%) samples from multiple sources, including wells, hand pumps, and taps, were positive for fecal coliforms. Of 1,885 households in the village, 450 (24%) households had no toilets and open defecation was commonly observed in the nearby river bed. CONCLUSIONS: This ADD outbreak was likely associated with drinking contaminated groundwater, which probably occurred after heavy rainfall in an area of open defecation. We recommended providing chlorinated drinking water, promoting safe sanitation practices, including building more public and private toilets, and enhancing diagnostic laboratory capacity.

Arsenic-hypertolerant and arsenic-reducing bacteria isolated from wells in Tucumán, Argentina.

Arsenic-hypertolerant bacteria were isolated from arsenic-contaminated well water from the village of Los Pereyra in Tucumán province, Argentina. Microorganisms that biotransform arsenic are a major factor in arsenic mobilization in contaminated aquifers. Groundwater analyses showed a level of arsenic contamination (mean concentration of 978 µg·L-1) that exceeds the safe drinking water limit of 10 µg·L-1 recommended by the World Health Organization and the Argentine Food Code. There was considerable spatial variability in the concentration of arsenic in each of the wells analyzed and in the distribution of the major anions HCO3-, SO42-, and Cl-. Eighteen bacterial strains were characterized. Six strains belonging to the Actinobacteria phylum were able to grow in media with 20 mmol·L-1 As(III) or 200 mmol·L-1 As(V) and were also highly resistant to Cr, Cd, and Cu. Their ability to biotransform arsenic was examined by speciation of the products by high-performance liquid chromatography inductively coupled plasma mass spectrometry. In addition, two strains, Brevibacterium sp. strain AE038-4 and Microbacterium sp. strain AE038-20, were capable of aerobic arsenate reduction, which suggests that these strains could increase the mobility of arsenic by formation of more mobile As(III).

Impact of the 2012 extreme drought conditions on private well owners in the United States, a qualitative analysis.

BACKGROUND: Extreme hot and dry weather during summer 2012 resulted in some of the most devastating drought conditions in the last half-century in the United States (U.S.). While public drinking water systems have contingency plans and access to alternative resources to maintain supply for their customers during drought, little is known about the impacts of drought on private well owners, who are responsible for maintaining their own water supply. The purpose of this investigation was to explore the public health impacts of the 2012 drought on private well owners' water quality and quantity, identify their needs for planning and preparing for drought, and to explore their knowledge, attitudes, and well maintenance behaviors during drought. METHODS: In the spring of 2013, we conducted six focus group discussions with private well owners in Arkansas, Indiana, and Oklahoma. RESULTS: There were a total of 41 participants, two-thirds of whom were men aged 55 years or older. While participants agreed that 2012 was the worst drought in memory, few experienced direct impacts on their water quantity or quality. However, all groups had heard of areas or individuals whose wells had run dry. Participants conserved water by reducing their indoor and outdoor consumption, but they had few suggestions on additional ways to conserve, and they raised concerns about limiting water use too much. Participants wanted information on how to test their well and any water quality issues in their area. CONCLUSIONS: This investigation identified information needs regarding drought preparedness and well management for well owners.

Development of a "big data" groundwater microbial contamination index and spatial comparisons with enteric infection rates in southern Ontario.

Big data have become increasingly important for policymakers and scientists but have yet to be employed for the development of spatially specific groundwater contamination indices or protecting human and environmental health. The current study sought to develop a series of indices via analyses of three variables: Non-E. coli coliform (NEC) concentration, E. coli concentration, and the calculated NEC:E. coli concentration ratio. A large microbial water quality dataset comprising 1,104,094 samples collected from 292,638 Ontarian wells between 2010 and 2021 was used. Getis-Ord Gi* (Gi*), Local Moran's I (LMI), and space-time scanning were employed for index development based on identified cluster recurrence. Gi* and LMI identify hot and cold spots, i.e., spatially proximal subregions with similarly high or low contamination magnitudes. Indices were statistically compared with mapped well density and age-adjusted enteric infection rates (i.e., campylobacteriosis, cryptosporidiosis, giardiasis, verotoxigenic E. coli (VTEC) enteritis) at a subregional (N = 298) resolution for evaluation and final index selection. Findings suggest that index development via Gi* represented the most efficacious approach. Developed Gi* indices exhibited no correlation with well density, implying that indices are not biased by rural population density. Gi* indices exhibited positive correlations with mapped infection rates, and were particularly associated with higher bacterial (Campylobacter, VTEC) infection rates among younger sub-populations (p < 0.05). Conversely, no association was found between developed indices and giardiasis rates, an infection not typically associated with private groundwater contamination. Findings suggest that a notable proportion of bacterial infections are associated with groundwater and that the developed Gi* index represents an appropriate spatiotemporal reflection of long-term groundwater quality. Bacterial infection correlations with the NEC:E. coli ratio index (p < 0.001) were markedly different compared to correlations with the E. coli index, implying that the ratio may supplement E. coli monitoring as a groundwater assessment metric capable of elucidating contamination mechanisms. This study may serve as a methodological blueprint for the development of big data-based groundwater contamination indices across the globe.

Arsenic Contamination of Groundwater Is Determined by Complex Interactions between Various Chemical and Biological Processes.

At a great many locations worldwide, the safety of drinking water is not assured due to pollution with arsenic. Arsenic toxicity is a matter of both systems chemistry and systems biology: it is determined by complex and intertwined networks of chemical reactions in the inanimate environment, in microbes in that environment, and in the human body. We here review what is known about these networks and their interconnections. We then discuss how consideration of the systems aspects of arsenic levels in groundwater may open up new avenues towards the realization of safer drinking water. Along such avenues, both geochemical and microbiological conditions can optimize groundwater microbial ecology vis-à-vis reduced arsenic toxicity.

An assessment of total coliforms and associated thresholds as water quality indicators using a large Ontario private drinking water well dataset.

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 (p < 0.05) 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.

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.

Approximately 1.6 million individuals in Ontario rely on private water wells. Private well water quality in Ontario remains the responsibility of the well owner, and due to the absence of regulation, quantitative microbial risk assessment (QMRA) likely represents the most effective approach to estimating and mitigating waterborne infection risk(s) from these supplies. Annual contamination duration (i.e., contaminated days per annum) represents a central input for waterborne QMRA; however, it is typically based on laboratory studies or meta-analyses, thus representing an important limitation for risk assessment, as groundwater mesocosms cannot accurately replicate subsurface conditions. The present study sought to address these limitations using a large spatio-temporal in-situ groundwater quality dataset (>700,000 samples) to evaluate aquifer-specific E. coli die-off rates (CFU/100 mL per day decline), subsequent contamination sequence duration(s) and the likelihood of overlapping contamination events. Findings indicate median E. coli die-off rates of 0.38 CFU/100 mL per day and 0.64 CFU/100 mL per day, for private wells located in unconsolidated and consolidated aquifers, respectlvely, with mean calculated contamination sequence durations of 18 days (unconsolidated) and 11 days (consolidated). Study findings support and permit development of increasingly evidence-based, regionally- and temporally-specific quantitative waterborne risk assessment.

Analysis of a large spatiotemporal groundwater quality dataset, Ontario 2010-2017: Informing human health risk assessment and testing guidance for private drinking water wells.

Approximately 1.5 million individuals in Ontario are supplied by private water wells (private groundwater supplies). Unlike municipal supplies, private well water quality remains unregulated, with owners responsible for testing, treating, and maintaining their own water supplies. The primary goal of this study was to assess the effect of repeat sampling of private well water in Ontario and investigate the efficacy of geographically- and/or temporally specific testing recommendations and health risk assessments. The current study combines the Well Water Information System Dataset and the Well Water Testing Dataset from 2010 to 2017, inclusive. These two large existing province-wide datasets collated over an eight-year period were merged using an integrated spatial fuzzy logic and (next)- nearest neighbour approach. Provincial sampling data from 239,244 wells (702,861 samples) were analyzed for Escherichia coli to study the relationship between sampling frequency and Escherichia coli detection. Dataset variables were delineated based on hydrogeological setting (e.g. aquifer type, overburden depth, well depth, bedrock type) and seasonality to provide an in-depth understanding of Escherichia coli detection in private well water. Findings reveal differences between detection rates in consolidated and unconsolidated aquifers (p = 0.0191), and across seasons (p < 0.0001). The variability associated with Escherichia coli detection rates was explored by estimating sentinel sampling rates for private wells sampled three times, twelve times and twenty-four times per year. As sample size increases on an annual basis, so too does detection rate, highlighting the need to address current testing frequency guidelines. Future health risk assessments for private well water should consider the impact of spatial and temporal factors on the susceptibility of this drinking water source, leading to an increasingly accurate depiction of private well water contamination and the estimated effects on human health.

Fluoride occurrence in United States groundwater.

Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concentrations >0.7 mg/L (U.S. Public Health Service recommended optimal F concentration in drinking water for preventing tooth decay) (87% are <0.7 mg/L); 2.6% have F > 2 mg/L (EPA Secondary Maximum Contaminant Level, SMCL); and 0.6% have F > 4 mg/L (EPA MCL). The data indicate the biggest concern with F in domestic wells at the national scale could be one of under consumption of F with respect to the oral-health benchmark (0.7 mg/L). Elevated F concentrations relative to the SMCL and MCL are regionally important, particularly in the western U.S. Statistical comparisons of potentially important controlling factors in four F-concentration categories (<0.1-0.7 mg/L; >0.7-2 mg/L; >2-4 mg/L; >4 mg/L) at the national scale indicate the highest F-concentration category is associated with groundwater that has significantly greater pH values, TDS and alkalinity concentrations, and well depths, and lower Ca/Na ratios and mean annual precipitation, than the lowest F-concentration category. The relative importance of the controlling factors appears to be regionally variable. Three case studies illustrate the spatial variability in controlling factors using groundwater-age (groundwater residence time), water-isotope (evaporative concentration), and water-temperature (geothermal processes) data. Populations potentially served by domestic wells with F concentrations <0.7, >0.7, >2, and >4 mg/L are estimated to be ~28,200,000, ~3,110,000; ~522,000; and ~172,000 people, respectively, in 40 principal aquifers with at least 25 F analyses per aquifer.

Hepatitis A Virus Infection from a Contaminated Tap of Ground Water Facility in a Neighborhood Park, Republic of Korea.

A patient with Hepatitis A virus (HAV) infection was notified to the public health authority. The identical HAV was found at a water dispensing outlet at the ground water facility and the toilet close to the facility. Serosurveillance in the community was conducted. Suspicious individuals were asked to visit city public health center and had a serologic test for anti-HAV Ig M. Overall, 100 individuals were tested, and all were negative for the anti-HAV Ig M. In our study cohort, we could not identify additional case of HAV infection.

Factors influencing perceptions of private water quality in North America: a systematic review.

BACKGROUND: An estimated four million and 43 million people in Canada and the USA use private water supplies. Private water supplies are vulnerable to waterborne disease outbreaks. Private water supplies in Canada and the USA are often unregulated and private water management is often a choice left to the owner. Perceptions of water quality become important in influencing the adoption of private water stewardship practices, therefore safeguarding public health. METHODS: We conducted a systematic literature review to understand factors that shape perceptions of water quality among private water users. We searched six computer databases (Web of science, Medline, Scopus, EBSCO, PubMed and Agricola). The search was limited to primary peer-reviewed publications, grey literature and excluded conference proceedings, review articles, and non-peer review articles. We restricted the search to papers published in English and to articles which published data on surveys of private water users within Canada and the USA. The search was also restricted to publications from 1986 to 2017. The literature search generated 36,478 records. Two hundred and four full text were reviewed. RESULTS: Fifty-two articles were included in the final review. Several factors were found to influence perceptions of water quality including organoleptic preferences, chemical and microbiological contaminants, perceived risks, water well infrastructure, past experience with water quality, external information, demographics, in addition to the values, attitudes, and beliefs held by well owners. CONCLUSIONS: Understanding the factors that shape perceptions of water quality among private water users is an important step in developing private water management policies to increase compliance towards water testing and treatment in Canada and the USA. As many jurisdictions in Canada and the USA do not have mandatory private water testing or treatment guidelines, delineating these factors is an important step in informing future research and guiding policy on the public health of private water systems.

The permuted locus trial--Well suited for emerging pathogens?

The recent Ebola virus epidemic was waning by the time stakeholders were ready to field vaccines for testing but an evidence-based response to a novel pathogen will surely be required again. Here, we present a design for such a randomized controlled trial. The permuted locus trial was originally intended for studying the influence of water wells on trachoma. While outcomes can be measured in individuals, neither individuals nor groups are themselves randomized to arms, just potential well-sites, or in the case of an epidemic, index cases. The permuted locus trial may be used when classic individual and cluster-randomized trial design and analyses may not be optimal.

Bacteriological testing of private well water: a trends and guidelines assessment using five years of submissions data from southeastern Ontario.

OBJECTIVE: Rural populations are at an elevated risk of gastrointestinal illness, as they are dependent on private groundwater sources, and water quality remains the responsibility of the owner. Previous research suggests that only a minority of well water owners test their wells for bacteriological contamination. The aim of this study was to use testing records, in conjunction with current provincial guidelines, to assess submission rates and temporal trends in southeastern Ontario. METHODS: Using five years of data (2008-2012) from the Public Health Ontario Laboratory in Kingston, Ontario, submissions of well water samples from unique properties (identified through geocoding) were descriptively analyzed. Temporal trends in guideline compliance were tested using a Cochran Armitage test. Finally, correlations between time and submission numbers were investigated using a 10-year provincial dataset to identify long-term temporal trends. RESULTS: There were 107,547 submissions in the five years studied, 84% of which were geocoded, culminating in 30,687 unique properties. Although 11%-12% of owners met the guidelines in any given year, only 0.3% met them every year in the five-year study. Statistically significant decreases were found temporally both in the number of properties that met current guidelines and in all samples tested. CONCLUSIONS: This study is the first to use submission records, rather than surveys, to definitively demonstrate that private well water submission guidelines are not being met in Ontario. However, there are no consistent guidelines across the country or continent, and limited supporting scientific literature is available. Significant research is required to develop evidence-based policies.

Wide diversity of fungal species found in wellwater for human consumption: an analytical cross-sectional study

ABSTRACT BACKGROUND: Fungi are ubiquitous in the environment. They are able to grow in water and many of them may be opportunistic pathogens. OBJECTIVE: The aims were to identify fungi in registered wells (RWs) and nonregistered wells (NRWs) that tap into groundwater; and to correlate the results from physicochemical assays on this water (free residual chlorine and pH) with the presence of fungi. DATA AND SETTING: Analytical cross-sectional quantitative study on groundwater wells in São José do Rio Preto, São Paulo, Brazil. METHODS: 52 samples of 500 ml of water were collected from RWs and 107 from NRWs. These were sent to a microbiology laboratory to identify any fungi that were present. In addition, free residual chlorine and pH were measured immediately after sample collection. Several statistical analysis tests were used. RESULTS: Fungal contamination was present in 78.8% of the samples from RWs and 81.3% from NRWs. Filamentous fungi were more prevalent than yeast in both types of wells. There was no significant difference in presence of fungi according to whether chloride and pH were within recommended levels in RWs; or according to whether pH was within recommended levels in NRWs. Furthermore, there was no statistical difference in the levels of fungal contamination between RWs and NRWs. CONCLUSION: Both RWs and NRWs are potential reservoirs for many types of fungi. Many of these may become opportunistic pathogens if they infect immunosuppressed individuals. Furthermore, this study confirms that fungi are able to grow even when chlorine and pH parameters are within the standards recommended.