Optimizing sampling location for water quality degradation monitoring in distribution systems: Assessing global representativeness and potential health risk.

Selecting the optimal monitoring points in a water distribution network is challenging due to the complex spatiotemporal variability of water quality degradation. The lack of a standardized methodology for monitoring point selection forces operators to rely on general recommendations, historical data and professional experience, which can mask water quality problems and increase the risk to consumers. This study proposes a new methodology to optimize the selection of monitoring points in distribution networks. The method considers the spatiotemporal degradation of water quality, the definition of representative zones and two selection criteria: global representativeness and potential health risk. Representative zones were determined for each node of the network based on hydraulic paths and their water quality spatial variability. Part of the distribution network in Quebec City, Canada was used as the case study, in which four water quality parameters were investigated: free chlorine residual (FRC), heterotrophic plate counts (HPC), trihalomethanes (THMs) and haloacetic acids (HAAs). Seasonal variabilities (summer and winter) were also analyzed. The results obtained for the two criteria and for both seasons were compared, and methodological and practical recommendations were established for dynamic monitoring programs that respond to the needs of operators.

Assessment of rain event effects on source water quality degradation and subsequent water treatment operations.

Heavy rainfall events can lead to the runoff of large amounts of dissolved and particulate matter into surface water sources that may represents challenges for drinking water treatment, such as membrane fouling, increases in chemical demands, and formation of various disinfection by products (DBPs) after disinfection, such as trihalomethanes (THM) and haloacetic acids (HAA). In this study, a framework is defined for analyzing water quality data in relation to climatic variables (rainfalls). The effects of 22 different rain events were assessed on an organic matter proxy (UV absorbance), and on different key water quality parameters for the coagulation step in a drinking water treatment plant. Extended impacts of rewetting events after long term dry period on source water quality were identified, with significant increases in raw water UV 254 nm that last almost 3 weeks. A significant effect on filtered water quality was also noticed and the potential impacts on finished waters quality was confirmed by HAA modelling results. Future studies could focus on the monitoring and modelling of other regulated DBPs such as THM as well as simulations of different scenarios of climate change to estimate the variability of DBPs and its precursors such as organic matter.

Drinking water management strategies for distribution networks: An integrated performance assessment framework.

Due to rapid population growth, urbanization, water contamination, and climate change, global water resources are under increasing pressure. Water utilities apply drinking water management strategies (DWMS) to ensure that water is safe for drinking. However, in recent years, due to increased inclination towards climate change, environmental emissions, and sustainable development goals; the environmental and economic performance of DWMSs is getting attention. An integrated framework combining life cycle thinking and water quality assessment techniques was developed in this study to evaluate the DWMSs' performance in terms of water quality, environment, and economics. Six DWMSs were assessed using the integrated framework as a case study. The environmental impacts in terms of human health, ecosystem, and resource use ranged from 1.46E-06 to 4.01E-06 DALY, 9.35E-10 to 3.80E-09 species.yr, and 0.0025-0.0071 USD-$, respectively. Pollution water index (PWI) and cost-benefit analysis (CBA) were used as decision-making techniques to assess the overall performance and suitability of DWMSs under given settings. The DWMSs with surface water as a source or ones providing relatively more degree of treatment have a relatively high PWI score (i.e., ≈0.31), reflective of high environmental impacts and water pollution compared to other alternatives. The CBA scores of selected alternatives ranged between 0.22 and 1.0. Furthermore, it was identified that DWMSs applied on relatively bigger water distribution systems can outweigh their costs (i.e., environmental and economic impacts). The proposed framework and approaches are flexible as they can incorporate different criteria in evaluating the performance and applicability of DWMSs.

Refined water security assessment for sustainable water management: A case study of 15 key cities in the Yangtze River Delta, China.

Water security represents ecological security and a policy priority for sustainable development; however, un-gridded assessment results cannot be used to support urban environmental management decisions. This study proposes a systematic framework to obtain a gridded regional water security assessment, which reflects the regional natural resource, based on the index system derived from the Pressure-State-Response (PSR) model and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The results were applied to sustainable water management. Using 15 key cities in the Yangtze River Delta (YRD) region as a case study to apply the methodology, we found that the comprehensive water security was relatively high and high-value areas were widely distributed, accounting for about two-thirds of the study area. Low-value areas were mainly distributed in central and eastern regions, such as Shanghai, Suzhou, and Nanjing. There was evidence of a water resource shortage during the twelve-month period studied, particularly in August. The proportions of comprehensive water security in each administrative unit and the differences between simulated and target water quality could be used in the spatial planning and the exploration of payments for ecosystem services (PES) mechanism in county-level or smaller administrative units. Despite the premise requirement and the grid resolution problems of the InVEST model, it can be concluded that our assessment method proves capable of matching spatial and temporal differences in water supply and demand at a fine scale, and results can be used to supply useful information for urban management decision making.

Perception of tap water quality: Assessment of the factors modifying the links between satisfaction and water consumption behavior.

Perception of tap water is subject to a wide range of factors and interactions. These include risk perception, tap water quality and organoleptic perceptions, microbiological and chemical quality, prior experiences, information sources, trust in water companies and other groups, and perceived control and contextual factors, among others. The objective of this study is to assess the factors that influence and determine citizen behavior regarding drinking water. A phone survey was conducted among 1014 citizens living in the city of Québec, Canada. Five different domestic water consumption profiles were elaborated according to the citizens' preferences and behavior. Descriptive statistics and mediation analyses were carried out to analyse the survey results and assess the factors modifying the links between satisfaction and water consumption behavior. Results show that drinking water quality could be loosely linked with overall satisfaction with tap water. The water consumption profile was strongly linked with satisfaction levels related to the taste, odor and color of tap water. We observed that the association between an individual's tap water satisfaction and water consumption behavior was mediated by the water treatment strategies applied at home (filtering, cooling), knowledge about drinking water quality and its production, and risk perception. The mediating effects were shown to be significant mainly among bottled-water-only and tap-water-only consumers. Future interventions that aim to encourage the population's use of tap water as a primary source should prioritize cooling and filtering tap water in their messaging, in order to improve population satisfaction. The reduction of risk perception through targeted information campaigns is also of primary importance for decreasing the number of citizens who exclusively drink bottled water.

Availability, Quality, and Relevance of Toxicogenomics Data for Human Health Risk Assessment: A Scoping Review of the Literature on Trihalomethanes.

Human health risk assessment (HHRA) must be adapted to the challenges of the 21st century, and the use of toxicogenomics data in HHRA is among the changes that regulatory agencies worldwide are trying to implement. However, the use of toxicogenomics data in HHRA is still limited. The purpose of this study was to explore the availability, quality, and relevance to HHRA of toxicogenomics publications as potential barriers to their use in HHRA. We conducted a scoping review of available toxicogenomics literature, using trihalomethanes as a case study. Four bibliographic databases (including the Comparative Toxicogenomics Database) were assessed. An evaluation table was developed to characterize quality and relevance of studies included on the basis of criteria proposed in the literature. Studies were selected and analyzed by 2 independent reviewers. Only 9 studies, published between 1997 and 2015, were included in the analysis. Based on the selected criteria, critical methodological details were often missing; in fact, only 3 out of 9 studies were considered to be of adequate quality for HHRA. No studies met >3 (out of 7) criteria of relevance to HHRA (eg, adequate number of doses and sample size). This first scoping review of toxicogenomics publications on trihalomethanes shows that low availability, quality, and relevance to HHRA of toxicogenomics publications presents potential barriers to their use in HHRA. Improved reporting of methodological details and study design is needed in the future so that toxicogenomics studies can be appropriately assessed regarding their quality and value for HHRA.

Barriers to the use of toxicogenomics data in human health risk assessment: A survey of Canadian risk assessors.

Regulatory agencies worldwide need to modernize human health risk assessment (HHRA) to meet challenges of the 21st century. Toxicogenomics is at the core of this improvement. Today, however, the use of toxicogenomics data in HHRA is very limited. The purpose of this survey was to identify barriers to the application of toxicogenomics data in HHRA by human health risk assessors. An online survey targeting Canadian risk assessors gathered information on their knowledge and perception of toxicogenomics, their current and future inclusion of toxicogenomics data in HHRA, and barriers to the use of such data. Twenty-nine (29) participants completed a questionnaire after 2 months of solicitation. The results show that the application of toxicogenomics data in Canada is marginal, with 85% of respondents reporting that they never or rarely used such data. Knowledge of toxicogenomics by Canadian risk assessors is also limited: about two-thirds of respondents (68%) were not at all or only slightly familiar with the concept. Lack of guidelines for toxicogenomics data interpretation, data quality assessment and on their use in HHRA, were found to be major barriers. In conclusion, there is a need for interventions aimed at facilitating the use of toxicogenomics data in HHRA, when available.

Investigating social inequalities in exposure to drinking water contaminants in rural areas.

Few studies have assessed social inequalities in exposure to drinking water contaminants. This study explores this issue in 593 rural municipalities of Québec, Canada. Quartiles of an ecological composite deprivation index were used as a proxy of socioeconomic status. Total trihalomethanes (TTHMs) and lead were chosen as proxies of chemical drinking water quality. The results show that the majority of deprived rural municipalities apply no treatment to their water (26%) or use a basic treatment (51%), whereas a relative majority of the wealthiest municipalities (40%) use advanced treatment. The proportion of municipalities having important lead (>5 µg/L) levels is highest in most deprived municipalities. Moreover, most deprived municipalities have a higher risk of high tap lead levels (RR = 1.33; 95%CI: 1.30, 1.36). Conversely, most deprived municipalities have a lower risk of high TTHMs levels (RR = 0.78; 95%CI: 0.69, 0.86). These findings suggest an environmental inequality in drinking water contaminants distribution in rural municipalities.

Integrating groundwater into land planning: a risk assessment methodology.

Generally, groundwater is naturally of good quality for human consumption and represents an essential source of drinking water. In Canada, small municipalities and individuals are particularly reliant on groundwater, since they cannot afford complex water treatment installations. However, groundwater is a vulnerable resource that, depending on its characteristics, can be contaminated by almost any land use. In recent decades, governments have launched programs to acquire more information on groundwater, in order to better protect it. Nevertheless, the data produced are rarely adequate to be understood and used by land planners. The aim of this study was to develop a method that helps planners interpret hydrogeological data in the Province of Quebec, Canada. Based on the requests and needs of planners during semi-directed interviews, a methodology was developed to qualitatively evaluate groundwater contamination risk by land uses. The method combines land planning data and hydrogeological data through the MACBETH multicriteria analysis method, to obtain maps of groundwater contamination risk. The method was developed through group and individual meetings with numerous hydrogeology, land planning, water's economics and drinking water specialists. The resulting maps allow planners to understand the dynamics of groundwater within their territory, identify problem areas where groundwater is threatened and analyse the potential impact of planning scenarios on the risk of groundwater contamination.

Multiparametric comparison of chromogenic-based culture methods used to assess the microbiological quality of drinking water and the mFC method combined with a molecular confirmation procedure.

MI agar and Colilert(®), as well as mFC agar combined with an Escherichia coli-specific molecular assay (mFC + E. coli rtPCR), were compared in terms of their sensitivity, ease of use, time to result and affordability. The three methods yielded a positive E. coli signal for 11.5, 10.8, and 11.5% of the 968 well water samples tested, respectively. One hundred and thirty-six (136) samples gave blue colonies on mFC agar and required confirmation. E. coli-specific rtPCR showed false-positive results in 23.5% (32/136) of cases. In terms of ease of use, Colilert was the simplest method to use while the MI method provided ease of use comparable to all membrane filtration methods. However, the mFC + E. coli rtPCR assay required highly trained employees for confirmation purposes. In terms of affordability, and considering contamination rate of well water samples tested, the Colilert method and the mFC + E. coli rtPCR assay were at least five times more costly than the MI agar method. Overall, compared with the other two methods tested, the MI agar method offers the most advantages to assess drinking water quality.

Disinfection byproducts in Canadian provinces: associated cancer risks and medical expenses.

Chlorination for drinking water forms various disinfection byproducts (DBPs). Some DBPs are probably linked to human cancer (e.g., bladder, colorectal cancers) and other chronic and sub-chronic effects. This emphasizes the need to understand and characterize DBPs in drinking water and possible risks to human health. In this study, occurrences of DBPs throughout Canada were investigated. Trihalomethanes (THMs) were observed to be highest in Manitoba followed by Nova Scotia and Saskatchewan, while haloacetic acids were highest in Nova Scotia followed by Newfoundland and Labrador. Based on the characterization of DBPs, risk of cancer from exposure to THMs was predicted using ingestion, inhalation and dermal contact pathways of exposure. In Canada, approximately 700 cancer cases may be caused by exposure to THMs in drinking water. Medical expenses associated with these cancer incidents are estimated at some $140 million/year. Expense may be highest in Ontario (∼$47 million/year) followed by Quebec (∼$25 million/year) due to a greater population base. This paper suggests improvements in water treatment, source protection and disinfection processes, and caution in the use of alternative disinfectants to reduce DBPs. Finally, elements are provided to mitigate risks and reduce cost estimates in future studies.

Multi-level modelling of chlorination by-product presence in drinking water distribution systems for human exposure assessment purposes.

During drinking water treatment and distribution, chlorine reacts with organic matter occurring in water to form various chlorination by-products (CBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). This paper presents the occurrence of THMs and HAAs in different water distribution systems (DS) of the same region and their modelling for exposure assessment purposes. This study was conducted in eight DS supplying chlorinated water to the population of Québec City, Canada. These systems differ in type of water source (i.e. surface, ground or mixed water), in treatment applied at the plant, and in size and structure of the DS. Two spatio-temporal databases for THMs and HAAs were implemented, one for model development and the other for model validation. The analysis of the data demonstrates significant seasonal and spatial variations of these compounds. A multi-level statistical modelling approach was applied to estimate the ranges for occurrence of THMs and HAAs in the eight DS (i.e. a single model for the study region for each CBP species). The modelling approach integrates available or easily measurable parameters. For both THMs and HAAs, a two-level model considering a sampling-site random effect was selected among various models initially developed. The model capacity for estimating the presence of THMs and HAAs in drinking water and its usefulness for exposure assessment purposes in the studied region was demonstrated.

Spatial variations of human health risk associated with exposure to chlorination by-products occurring in drinking water.

During disinfection, chlorine reacts with organic matter present in drinking water and forms various undesirable chlorinated by-products (CBPs). This paper describes a study of the spatial variability of human health risk (i.e., cancer effects) from CBP exposure through drinking water in a specific region. The region under study involves nine drinking water distribution systems divided into several zones based on their characteristics. The spatial distribution of cancer risk (CR) was estimated using two years of data (2006-2008) on various CBP species. In this analysis, trihalomethanes (THMs) and haloacetic acids (HAAs) served as surrogates for CBPs. Three possible routes of exposure (i.e., via ingestion, inhalation and dermal contact) were considered for each selected compound. The cancer risk assessment involved estimating a unit risk (R(T)) in each zone of the selected distribution systems. A probabilistic analysis based on Monte Carlo simulations was employed. Risk assessment results showed that cancer risk varied between systems, but also within individual systems. As a result, the population of the same region was not exposed to the same risk associated with CBPs in drinking water. Unacceptable levels (i.e., R(T) > 10(-4)) for the estimated CR were determined for several zones in the studied region. This study demonstrates that a spatial-based analysis performed to represent the spatial distribution of risk estimates can be helpful in identifying suitable risk management strategies. Suggestions for improving the risk analysis procedure are also presented.

The assessment of population exposure to chlorination by-products: a study on the influence of the water distribution system.

BACKGROUND: The relationship between chlorination by-products (CBPs) in drinking water and human health outcomes has been investigated in many epidemiological studies. In these studies, population exposure assessment to CBPs in drinking water is generally based on available CBP data (e.g., from regulatory monitoring, sampling campaigns specific to study area). Since trihalomethanes (THMs) and haloacetic acids (HAAs) are the most documented CBP classes in drinking water, they are generally used as indicators of CBP exposure. METHODS: In this paper, different approaches to spatially assign available THM and HAA concentrations in drinking water for population exposure assessment purposes are investigated. Six approaches integrating different considerations for spatial variability of CBP occurrence within different distribution systems are compared. For this purpose, a robust CBP database (i.e., high number of sampling locations selected according to system characteristics) corresponding to nine distribution systems was generated. RESULTS AND CONCLUSION: The results demonstrate the high impact of the structure of the distribution system (e.g., presence of intermediary water infrastructures such as re-chlorination stations or reservoirs) and the spatial variability of CBPs in the assigned levels for exposure assessment. Recommendations for improving the exposure assessment to CBPs in epidemiological studies using available CBP data from water utilities are also presented.

Using multi-criteria decision analysis to assess the vulnerability of drinking water utilities.

Outbreaks of microbiological waterborne disease have increased governmental concern regarding the importance of drinking water safety. Considering the multi-barrier approach to safe drinking water may improve management decisions to reduce contamination risks. However, the application of this approach must consider numerous and diverse kinds of information simultaneously. This makes it difficult for authorities to apply the approach to decision making. For this reason, multi-criteria decision analysis can be helpful in applying the multi-barrier approach to vulnerability assessment. The goal of this study is to propose an approach based on a multi-criteria analysis method in order to rank drinking water systems (DWUs) based on their vulnerability to microbiological contamination. This approach is illustrated with an application carried out on 28 DWUs supplied by groundwater in the Province of Québec, Canada. The multi-criteria analysis method chosen is measuring attractiveness by a categorical based evaluation technique methodology allowing the assessment of a microbiological vulnerability indicator (MVI) for each DWU. Results are presented on a scale ranking DWUs from less vulnerable to most vulnerable to contamination. MVI results are tested using a sensitivity analysis on barrier weights and they are also compared with historical data on contamination at the utilities. The investigation demonstrates that MVI provides a good representation of the vulnerability of DWUs to microbiological contamination.

A registry of the aetiology and costs of neuropathic pain in pain clinics : results of the registry of aetiologies and costs (REC) in neuropathic pain disorders study.

OBJECTIVE: The aim of this study was to determine health resource consumption and costs in patients with neuropathic pain managed in pain clinics in Spain. METHODS: This was a retrospective, cross-sectional study performed in 2004 in 18 pain clinics across Spain. Consecutive neuropathic pain patients were recruited between April and December 2004. Demographic data, type and cause of neuropathic pain, source of referral and utilisation of health resources (treatments, medical visits, hospital admissions, etc.) were collected. Direct medical costs were estimated using 2004 prices. Descriptive statistics and ANCOVA models were used for significance. RESULTS: The study included 504 patients with neuropathic pain of broad aetiologies (44% radiculopathies, 21% neuralgias, 11% neuropathies, 7% entrapment syndromes, 5% complex regional painful syndrome, 4% central pain), aged 57.8 +/- 0.7 years (mean +/- SE), 57.6% of whom were women. The mean time since diagnosis was 23.7 +/- 26.8 months. Two groups of patients according to type of pain management were also identified: those referred to pain clinics for pain control from primary-care/other specialists (r-PC, n = 326) and those primarily managed at pain clinics (p-PC, n = 178). The adjusted mean monthly total cost was 363 euros per patient with no statistically significant differences between type of care: 376 euros (p-PC) versus 344 euros (r-PC) [p = 0.626]. Acquisition monthly mean drug costs were higher in the p-PC group: 131 euros (34.8% of total costs) versus 80 euros (23.3%) per patient (p = 0.0001). However, emergency-room visits, primary-care visits and number of treatment drugs were significantly higher in the r-PC group: 0.27, 0.20 and 2.90 visits/drugs per patient per month versus 0.13, 0.10 and 2.50, respectively (p < 0.01 in all cases). There were also more diagnostic tests and specialised physician visits and higher hospitalisation costs in r-PC subjects (differences not statistically significant). CONCLUSIONS: Neuropathic pain results in a substantial utilisation of health resources, particularly by patients referred by primary-care/other specialists to pain clinics for pain control. However, compared with subjects whose pain is primarily managed in pain clinics, the extra health costs arising from drug acquisition observed in such patients are offset by lower costs of the other components of pain management, producing similar mean monthly total costs.