Showing papers in "Journal of Water and Health in 2005"

Deficiencies in drinking water distribution systems in developing countries.

Abstract: Rapidly growing populations and migration to urban areas in developing countries has resulted in a vital need for the establishment of centralized water systems to disseminate potable water to residents. Protected source water and modern, well-maintained drinking water treatment plants can provide water adequate for human consumption. However, ageing, stressed or poorly maintained distribution systems can cause the quality of piped drinking water to deteriorate below acceptable levels and pose serious health risks. This review will outline distribution system deficiencies in developing countries caused by: the failure to disinfect water or maintain a proper disinfection residual; low pipeline water pressure; intermittent service; excessive network leakages; corrosion of parts; inadequate sewage disposal; and inequitable pricing and usage of water. Through improved research, monitoring and surveillance, increased understanding of distribution system deficiencies may focus limited resources on key areas in an effort to improve public health and decrease global disease burden.

A review of technologies for rapid detection of bacteria in recreational waters.

Abstract: Monitoring of recreational beaches for fecal indicator bacteria is currently performed using culturebased technology that can require more than a day for laboratory analysis, during which time swimmers are at risk. Here we review new methods that have the potential to reduce the measurement period to less than an hour. These methods generally involve two steps. The first is target capture, in which the microbial group of interest (or some molecular/chemical/or biochemical signature of the group) is removed, tagged or amplified to differentiate it from the remaining material in the sample. We discuss three classes of capture methods: 1) Surface and whole-cell recognition methods, including immunoassay techniques and molecule-specific probes; 2) Nucleic acid methods, including polymerase chain reaction (PCR), quantitative PCR (Q-PCR), nucleic acid sequence based amplification (NASBA) and microarrays; and 3) Enzyme/substrate methods utilizing chromogenic or fluorogenic substrates. The second step is detection, in which optical, electrochemical or piezoelectric technologies are used to quantify the captured, tagged or amplified material. The biggest technological hurdle for all of these methods is sensitivity, as EPA’s recommended bathing water standard is less than one cell per ml and most detection technologies measure sample volumes less than 1ml. This challenge is being overcome through addition of preconcentration or enrichment steps, which have the potential to boost sensitivity without the need to develop new detector technology. The second hurdle is demonstrating a relationship to health risk, since most new methods are based on measuring cell structure without assessing viability and may not relate to current water quality standards that were developed in epidemiology studies using culture-based methods. Enzyme/substrate methods may be the first rapid methods adopted because they are based on the same capture technology as currentlyapproved EPA methods and their relationship to health risk can be established by demonstrating equivalency to existing procedures. Demonstration of equivalency may also be possible for some surface and whole-cell recognition methods that capture bacteria in a potentially viable state. Nucleic acid technologies are the most versatile, but measure nonviable structure and will require inclusion in epidemiological studies to link their measurement with health risk.

Microbial quality of runoff following land application of cattle manure and swine slurry

Abstract: Concentrations of human health-related microorganisms in runoff from agricultural plots (0.75m £ 2m) treated with fresh and aged cattle manure, swine slurry and no manure (control) were determined. Three consecutive simulated rainfall events, producing 35mm rainfall and separated by 24h, were carried out for each plot. Fecal indicator (Escherichia coli, enterococci, Clostridium perfringens and coliphage) loads released in rainfall runoff from plots treated with fresh cattle manure, aged cattle manure and swine slurry treatments ranged from 5.52 £ 10 5 to 4.36 £ 10 9 , 3.92 £ 10 4 to 4.86 £ 10 8 , and 9.63 £ 10 5 to 3.05 £ 10 8 , respectively. Plot runoff concentrations of protozoa (Cryptosporidium oocysts and Giardia cysts) ranged from 1.65 £ 10 5 to 1.04 £ 10 6 , 2.93 £ 10 3 to 2.75 £ 10 5 , and 9.12 £ 10 4 to 3.58 £ 10 6 for fresh cattle manure, aged cattle manure and swine slurry plot treatments, respectively. These results suggest that large microbial loads could be released via heavy precipitation events that produce runoff from livestock manure-applied agricultural fields, of even modest size, and could have a significant impact on water bodies within the watershed. Because of the lack of multiplication in the environment, highly elevated concentrations in manured land runoff, and correlation to protozoan parasite presence, Clostridium may be an alternative indicator for livestock manure contamination.

Ferrates (iron(VI) and iron(V)): environmentally friendly oxidants and disinfectants.

Abstract: Iron(VI) and iron(v), known as ferrates, are powerful oxidants and their reactions with pollutants are typically fast with the formation of non-toxic by-products. Oxidations performed by Fe(VI) and Fe(V) show pH dependence; faster rates are observed at lower pH. Fe(VI) shows excellent disinfectant properties and can inactivate a wide variety of microorganisms at low Fe(VI) doses. Fe(VI) also possesses efficient coagulation properties and enhanced coagulation can also be achieved using Fe(VI) as a preoxidant. The reactivity of Fe(V) with pollutants is approximately 3-5 orders of magnitude faster than that of Fe(VI). Fe(V) can thus be used to oxidize pollutants and inactivate microorganisms that have resistance to Fe(VI). The final product of Fe(VI) and Fe(V) reduction is Fe(III), a non-toxic compound. Moreover, treatments by Fe(VI) do not give any mutagenic/carcinogenic by-products, which make ferrates environmentally friendly ions. This paper reviews the potential role of iron(VI) and iron(V) as oxidants and disinfectants in water and wastewater treatment processes. Examples are given to demonstrate the multifunctional properties of ferrates to purify water and wastewater.

Induction of Escherichia coli and Salmonella typhimurium into the viable but nonculturable state following chlorination of wastewater.

Abstract: We examined the effects of chlorine disinfection on Escherichia coli and Salmonella typhimurium in secondary-treated wastewater to determine whether such treatment might induce these bacteria into the viable but nonculturable (VBNC) state. In this state, cells lose culturability but retain viability and the potential to revert to the metabolically active and infectious state. To examine the effects of chlorination on cells in different physiological states, cells from the logarithmic and stationary phases, or nutrient starved, or grown in natural wastewater, were studied. Isogenic cells with and without plasmids were also examined. Whereas a mixture of free and combined chlorine, as occurs under typical wastewater disinfection, was found to be rapidly lethal to most cells, regardless of their physiological state or plasmid content, c. 10 4 of the original 10 6 cells ml −1 did survive in the VBNC state. While we were not successful in resuscitating these cells to the culturable state, the presence of such nonculturable cells in treated wastewater offers a potential public health hazard.

Home water treatment by direct filtration with natural coagulant

Abstract: Seeds of the plant species Strychnos potatorum and Moringa oleifera contain natural polyelectrolytes which can be used as coagulants to clarify turbid waters. In laboratory tests, direct filtration of a turbid surface water (turbidity 15-25 NTU, heterotrophic bacteria 280-500 cfu ml(-1), and fecal coliforms 280-500 MPN 100 ml(-1)), with seeds of S. potatorum or M. oleifera as coagulant, produced a substantial improvement in its aesthetic and microbiological quality (turbidity 0.3-1.5 NTU, heterotrophic bacteria 5-20 cfu ml(-1) and fecal coliforms 5-10 MPN 100 ml(-1)). The method appears suitable for home water treatment in rural areas of developing countries. These natural coagulants produce a 'low risk' water; however, additional disinfection or boiling should be practised during localised outbreaks/epidemics of enteric infections.

The importance of domestic water quality management in the context of faecal-oral disease transmission.

Abstract: The deterioration of drinking water quality following its collection from a community well or standpipe and during storage in the home has been well documented However, there is a view that post-supply contamination is of little public health consequence This paper explores the potential health risk from consuming re-contaminated drinking water A conceptual framework of principal factors that determine the pathogen load in household drinking water is proposed Using this framework a series of hypotheses are developed in relation to the risk of disease transmission from re-contaminated drinking water and examined in the light of current literature and detailed field observation in rural Honduran communities It is shown that considerable evidence of disease transmission from re-contaminated drinking water exists In particular the type of storage container and hand contact with stored drinking water has been associated with increased incidence of diarrhoeal disease There is also circumstantial evidence linking such factors as the sanitary conditions in the domestic environment, cultural norms and poverty with the pathogen load of household stored drinking water and hence the risk of disease transmission In conclusion it is found that re-contaminated drinking water represents a significant health risk especially to infants, and also to those with secondary immunodeficiency

Effects of weather and river flow on cryptosporidiosis

Abstract: Outbreaks of cryptosporidiosis have been linked to weather patterns such as heavy precipitation. However, outbreaks only account for a small percentage of all cryptosporidiosis cases and so the causes of the majority of cases are uncertain. This study assessed the role of environmental factors in all cases of cryptosporidiosis by using ordinary least-squares regression to examine the relationship between the monthly cryptosporidiosis rate, and the weather and river flows in England and Wales between 1989 and 1996. Between April and July the cryptosporidiosis rate was positively related to maximum river flow in the current month. Between August and November cryptosporidiosis was also positively linked to maximum river flows in the current month but only after accounting for the previous month's temperature, precipitation and monthly cryptosporidiosis rate. No associations were found between December and March. Through an understanding of the environmental processes at work, these relationships are all consistent with an animal to human transmission pathway especially as the relationships vary throughout the year. This study therefore indicates the importance of an animal to human transmission pathway for all cases of cryptosporidiosis.

Comparison of disinfectants for biofilm, protozoa and Legionella control.

Abstract: The aim of this study was to compare the efficiency of different disinfectants applicable to Legionella control in domestic water systems. A domestic water supply simulation unit that allowed simulation of real-world conditions was developed for this purpose. The system, consisting of seven identical rigs, was used to compare treatment efficiency under equivalent conditions of system design, materials, hydraulics, water quality, temperature and initial contamination. During the study, each of six loops received continuous application of one of the following disinfectants: chlorine, electro-chlorination, chlorine dioxide, monochloramine, ozone, or copper/silver. The seventh loop was used as a control and remained untreated. Performance evaluation of these disinfectants was based on their ability to reduce not only Legionella, but also protozoa and biofilms, which contribute to the establishment and dissemination of these bacteria in water systems, and their resistance to treatments. Regarding these criteria, chlorine dioxide and chlorine (as bleach or obtained by electro-chlorination) were the most effective treatments in this study. However, in comparison with chlorine, chlorine dioxide showed a longer residual activity in the system, which constituted an advantage in the perspective of an application to extensive pipework systems.

Quantifying the impact of runoff events on microbiological contaminant concentrations entering surface drinking source waters.

Abstract: Concentrations of microbiological contaminants in streams increase during rainfall-induced higher flow ‘event’ periods as compared to ‘baseflow’ conditions. If the stream feeds a drinking water reservoir, such periods of heightened pathogen loads may pose a challenge to the water treatment plant and subsequently a health concern to water consumers downstream. In order to manage this risk, it is desirable to first quantify the differences in surface water quality between baseflow and event conditions. The Event Mean Concentration (EMC) is a flow-weighted average concentration of a contaminant over the duration of a single event, proposed here as a standard parameter for quantifying the net effect of events on microbial water quality. Application of the EMC concept was assessed using flow and quality data for several events from an urbanised catchment. Expected mean EMCs were significantly larger than expected mean baseflow concentrations (p-value#0.012) for three microbial agents - Escherichia coli (13,000 [n ¼ 7] v. 610 [n ¼ 16] mpn/100ml), Cryptosporidium (234 [n ¼ 6] v. 51 [n ¼ 16] oocysts/10 litres) and Campylobacter (48 [n ¼ 5] v. 2.1 [n ¼ 16] mpn/100ml). These parameter estimates were complemented by estimating data variability and uncertainty in the form of second-order random variables. As such the results are in a format appropriate for potential use as components in probabilistic risk assessments evaluating the effect runoff events have on drinking water quality.

Effect of precipitation on seasonal variability in cryptosporidiosis recorded by the North West England surveillance system in 1990-1999.

Abstract: The goal of this study was to examine temporal and spatial variability of reported cryptosporidiosis in 15 health authorities in the North West of England using regression modelling. We also examined the role of precipitation as a driving factor for seasonal variation. We separated the time series of the reported cryptosporidiosis into two processes: an endemic process and an epidemic process, and examined the spatial variability of each of these processes. In the North West region of England we observed a strong seasonal pattern that consists of two waves, spring and autumn, during which the weekly rates exceeded the endemic level 3.5 and 3 times, respectively. Health authorities with the high endemic cryptosporidiosis incidence and well-pronounced seasonal patterns exhibited a significant increase in rates of cryptosporidiosis associated with increased precipitation. The endemic level and the magnitude of epidemic peaks were inversely related, which might be indicative of multiple exposures to the pathogen in these localities and the development of some partial immunity.

Effective water supply surveillance in urban areas of developing countries.

Abstract: Water supply surveillance generates data on the safety and adequacy of drinking water supply in order to contribute to the protection of human health. Most current models of water supply surveillance for urban areas come from developed countries and have significant shortcomings if directly applied elsewhere. There are differences not only in socio-economic conditions but also in the nature of water supply services, which often comprise a complex mixture of formal and informal services for both the ‘served’ and ‘unserved’. The development of approaches to water supply surveillance that allow targeting of activities on priority groups is assessed based on case studies from Peru and Uganda. The development of a zoning approach that incorporates indices for vulnerability is shown to be a useful tool to assist surveillance in targeting data collection. Zoning also assists in targeting subsequent interventions into communities and strategies where public health gains are likely to be greatest. Two approaches to urban zoning are presented from Peru and Uganda, both of which are effective.

Aspects of health-related microbiology of the Subin, an urban river in Kumasi, Ghana

Abstract: The aim of this study was to assess the influence of urban waste, sewage and other human centred activities on the microbiological quality of the river Subin, which flows through the metropolis of Kumasi, Ghana, and serves as drinking water for communities downstream. Three sites, Racecourse, Asafo and Asago, on the Subin were monitored over a year for total coliforms, faecal coliforms, enterococci and biochemical oxygen demand. Bacterial indicator numbers (geometric mean 100 ml(-1)) varied from 1.61 x 10(9) to 4.06 x 10(13) for total coliforms, 9.75 x 10(8) to 8.98 x 10(12) for faecal coliforms and 1.01 x 10(2) to 6.57 x 10(6) for enterococci. There was a consistent increase in bacterial loading as the river flows from the source (Racecourse) through Kumasi. Bacterial numbers were significantly (p < or = 0.05) higher during the rainy season compared with the dry (harmattan) season. The biochemical oxygen demand ranged from 8 mg l(-1) at the source of the river to 419 mg l(-1) at Asago; none of the sites achieved internationally accepted standards for water quality. The River Subin becomes grossly polluted as it flows through Kumasi and at Asago, a rural community downstream of Kumasi that abstracts water from the river for drinking, this probably contributes to the observed high levels of diarrhoeal disease.

An estimation of the global burden of disease due to skin lesions caused by arsenic in drinking water

Abstract: The global burden of disease due to skin lesions caused by arsenic in drinking water was estimated by combining country-based exposure data with selected exposure-response relationships derived from the literature. Populations were considered to be exposed to elevated arsenic levels if their drinking water contained arsenic concentrations of 50 microg I(-1) or greater. Elevated arsenic concentrations in drinking water result in a significant global burden of disease, even when confining the health outcome to skin lesions. The burden of disease was particularly marked in the World Health Organization (WHO) comparative risk assessment (CRA) 'Sear D' region, which includes Bangladesh, India and Nepal. Unsurprisingly, Bangladesh was the worst affected country with 143 disability adjusted life years (DALYs) per 1,000 population. Although this initial estimate is subject to a large degree of uncertainty, it does represent an important first step in allowing the comparison of the problem relating to elevated arsenic in drinking water to other environmental health outcomes.

Occurrence and correlations between coliphages and anthropogenic viruses in the Massachusetts Bay using enrichment and ICC-nPCR.

Abstract: We evaluated a two-step enrichment procedure to detect coliphages and an integrated cell culturenested polymerase chain reaction (ICC-nPCR) to detect human astrovirus, enteroviruses, rotavirus and adenovirus type 40 and 41 in marine water samples collected by the Massachusetts Water Resource Authority (MWRA). MWRA has been monitoring its receiving waters for coliphages, anthropogenic viruses and indicator bacteria in order to evaluate the impact of Boston’s Deer Island Sewage Treatment Plant discharge. Coliphages and enteric viruses were originally assayed using single agar overlay and most probable number cell culture (MPN) methods, respectively. Reanalysis of these samples for enteric viruses by ICC-nPCR demonstrated that 46% were positive for at least one virus compared with 23% with the MPN method. Use of the enrichment method showed a 47% increase in the detection of male specific and somatic coliphages compared with the single agar overlay method. Correlations between the presence of coliphages, enteric viruses and indicator bacteria were based on proximity to the treatment plant discharge, seasonal variations and site levels. The presence of enteric viruses was significantly correlated to coliphages but not to indicator bacteria. Preliminary comparative results demonstrate that effective and efficient monitoring of anthropogenic contamination can be achieved using these more sensitive and specific techniques.

Drinking water quality and solar disinfection: effectiveness in peri-urban households in Nepal.

Abstract: The study examined pH, turbidity and fecal contamination of drinking water from household water storage containers, wells and taps, and the Godawari River, and tested the effectiveness of solar disinfection (SODIS) in reducing levels of fecal contamination from household containers. The research was conducted in 40 households in a village 6km outside the capital city of Kathmandu, Nepal. Three rounds of data were collected: a baseline in March 2002 followed by training in solar disinfection, and follow-ups in June and July 2002. Untreated drinking water was found to have levels of contamination ranging from 0 to too numerous to count fecal coliform CFU 100ml - 1 . Source water was significantly more contaminated than water from the household storage containers. wells were less contaminated than taps. SODIS reduced the level of contamination under household conditions. Turbidity from taps was above 30 NTU in the rainy season, above the maximum for effective solar disinfection. SODIS was routinely adopted by only 10% of the participating households during the study.

The adsorption of cyanobacterial hepatoxins as a function of soil properties.

Abstract: Cyanobacterial hepatotoxins present a risk to public health when present in drinking water supplies. Existing removal strategies, although efficient, are not economically viable or practical for remote Australian communities and developing nations. Bank filtration is a natural process and a potential low cost, toxin removal strategy. Batch studies were conducted in 12 texturally diverse soils to examine the soil properties influencing the adsorption of the cyanobacterial hepatotoxins, microcystin-LR and nodularin. Sorption isotherms were measured. Freundlich and linear isotherms were observed for both toxins with adsorption coefficients not exceeding 2.751 kg(-1) for nodularin and 3.81 kg(-1) for microcystin. Significant positive correlations were identified between hepatotoxin sorption and clay and silt contents of the soils. Desorption of toxins was also measured in three different soils. Pure nodularin and microcystin-LR readily desorbed from all soils.

Detection of Helicobacter pylori and fecal indicator bacteria in five North American rivers

Abstract: This study examines the use of fecal indicator bacteria (FIB) as a predictor of the presence of Helicobacter spp. A combination of standard culture and molecular techniques were used to detect and quantify FIB, Helicobacter spp. and H. pylori from five North American rivers of different size and with different land use characteristics. Primers designed to amplify genes specific to Helicobacter spp. and H. pylori were evaluated for their efficacy in detection and quantification in environmental samples. Helicobacter spp. were detected in 18/33 (55%) of river samples. H. pylori was detected in 11/33 (33%) of river samples. FIB were found in 32/33 (96%) of river samples. When FIB abundance exceeded USEPA water quality standards for single samples, Helicobacter or H. pylori were detected in 7/15 (47%) cases. No numerical correlation was found between the presence of FIB and either Helicobacter spp. or H. pylori. This suggests that the presence of FIB will be of limited use for detection of Helicobacter spp. or H. pylori by public health agencies.

A pilot randomized, controlled trial of an in-home drinking water intervention among HIV + persons.

Abstract: Although immunocompromised persons may be at increased risk for gastrointestinal illnesses, no trials investigating drinking water treatment and gastrointestinal illness in such patients have been published. Earlier results from San Francisco suggested an association (OR 6.76) between tap water and cryptosporidiosis among HIV þ persons. The authors conducted a randomized, triple-blinded intervention trial of home water treatment in San Francisco, California, from April 2000 to May 2001. Fifty HIV-positive patients were randomized to externally identical active (N = 24) or sham (N = 26) treatment devices. The active device contained a filter and UV light; the sham provided no treatment. Forty-five (90%) of the participants completed the study and were successfully blinded. Illness was measured using ‘highly credible gastrointestinal illness’ (HCGI), a previously published measure. There were 31 episodes of HCGI during 1,797 person-days in the sham group and 16 episodes during 1,478 person-days in the active group. The adjusted relative risk was 3.34 (95% CI: 0.99–11.21) times greater in those with the sham device. The magnitude of the point estimate of the risk, its consistency with recently published observational data, and its relevance for drinking water choices by immunocompromised individuals support the need for larger trials.

Quantitative detection of enteroviruses in activated sludge by cell culture and real-time RT-PCR using paramagnetic capturing.

Abstract: We have compared in extracts of activated sludge the number of enteroviruses detectable with buffalo green monkey (BGM) cell-cultures versus the number of enteroviral genomes determined by reverse-transcription quantitative real-time PCR (RT-qPCR). In order to find conditions adequate for quantifying enteroviral RNA isolated from (waste)water we have investigated affinity capture of RNA with polystyrene beads (Dynabeads). The capture efficiency strongly depended on the genomic region chosen for the affinity binding. Capture of the RNA by its 3'-tail was most efficient (almost 100%); other regions within the genome yielded variable but lower results. Indirect capture (first hybridization of the RNA to the oligonucleotides, then attachment of the duplex molecules to the beads) was much more efficient than direct capture (attachment of the oligonucleotides to the beads first, then binding of the RNA), and resulted in RNA capture of maximally 60-80%. At least partly, this was due to incomplete hybridization of the RNA to the complementary oligonucleotides. No correlation was found between the number of cytopathic effects (CPE) determined by cell culture and the number of genomes quantified by RT-qPCR; RT-qPCR values were consistently much higher than the number of CPE. This points to overestimation of infectious enteroviruses by RT-qPCR and/or underestimation by the cell culture approach.

Heterogeneity of uidA gene in environmental Escherichia coli populations

Abstract: Previous studies have shown that Escherichia coli can be isolated from non-polluted rivers and from bromeliad axilae in pristine areas of tropical rain forests. Finding E. coli in pristine environments is unusual because this bacterium is thought to only survive in the gut of warm-blooded animals and thus its presence should indicate recent fecal contamination. The aims of this study were 1) to determine if E. coli is part of the native soil microbiota in tropical rain forests and 2) to determine if genetic heterogeneity exists among E. coil populations. High concentrations of total coliforms (10(4)-10(5) cells per 10 g of soil dry weight) and low concentrations of thermotolerant coliforms (10(1)-10(2) cells per 10 g dry soil, the majority of these were found to be E. coli) were detected. PCR using uidA-specific primers was done on DNA purified from E. coli isolates and the resulting amplicons analysed by denaturing-gradient gel electrophoresis (DGGE). Out of several hundred isolates, mixtures of nine different amplicons were consistently observed. The different patterns of DGGE observed indicate that the E. coli populations in these pristine soils are genetically heterogeneous. Fecal and environmental E. coli isolates were also analysed by pulsed-field gel electrophoresis (PFGE) which showed high DNA sequence variation among the E coli isolates. Because of these differences in the genomes, PFGE did not allow grouping of environmental versus human isolates of E. coli when compared side to side. The apparent genetic polymorphisms, as a result of genetic heterogeneity, observed in isolates from the same pristine site indicate that source tracking may be difficult to carry out using E. coli as the target organism.

Microcystins (cyanobacterial toxins) in surface waters of rural Bangladesh: pilot study.

Abstract: In Bangladesh the exposure of millions of inhabitants to water from (shallow) tube wells contaminated with high geogenic loads of arsenic is a major concern. As an alternative to the costly drilling of deep wells, the return to the use of surface water as a source of drinking water is considered. In addition to the well-known hazards of water borne infectious diseases associated with the use of surface water, recently the potential public health implications of toxic cyanobacteria have been recognized. As a first step towards a risk assessment for cyanotoxins in Bangladesh surface waters, seston samples of 79 ponds were analysed in late summer 2002 for the presence of cyanobacteria and microcystins (MCYST), the most frequently detected cyanobacterial toxins worldwide. Microcystins could be detected in 39 ponds, mostly together with varying abundance of potentially microcystin-producing genera such as Microcystis, Planktothrix and Anabaena. Total microcystin concentrations ranged between 1,000 microg l(-1), and more than half of the positive samples contained high concentrations of more than 10 microg l(-1). The results clearly show that concentrations of microcystins well above the provisional WHO guideline value of 1 microg l(-1) MCYST-LR can be frequently detected in Bangladesh ponds. Thus, an increasing use of surface water for human consumption introduces a risk of replacing one health hazard by another and therefore needs to be accompanied by cyanotoxin hazard assessments.

Seasonal virus removal by alternative onsite wastewater treatment systems

Abstract: Viral contamination of public waters is a leading health concern around the world, including in Minnesota where cold climate, abundant onsite systems on poor or thin soils, and abundant surface water resources present a significant risk of wastewater pathogens reaching sensitive water sources. Three alternative onsite treatment systems, a sand filter, peat filter and subsurface-flow constructed wetland (CW) at a field research site were evaluated for seasonal virus removal by seeding each with MS2 bacteriophage. The sand and peat filters and CW removed 2.7, 7.0, and 1.4 log10 of MS2, respectively, during summer and 1.8 and 6.9 log for the sand and peat filter during winter (CW not seeded). Somatic coliphage reductions for the sand filter, peat filter and CW were 2.9, 3.5, 1.0 log10 in summer, and 1.5, 2.8, 0.7 log10 during winter, respectively over a 3 year period. During this period, fecal coliform log10 reductions were 2.9, 4.6, 2.0 in summer for the sand and peat filters and CW, and 2.0, 4.6, 1.6 in winter. The peat filter was the most effective system for removing MS2, somatic coliphage and fecal coliforms during both winter and summer but all systems removed .90% of viruses throughout the year.

Status of groundwater arsenic contamination and human suffering in a Gram Panchayet (cluster of villages) in Murshidabad, one of the nine arsenic affected districts in West Bengal, India.

Abstract: A detailed study was carried out in a cluster of villages known as Sagarpara Gram Panchayet (GP), covering an area of 20 km 2 and population of 24,419 to determine the status of groundwater arsenic contamination and related health effects. The arsenic analysis of all hand tubewells (n = 565) in working condition showed, 86.2% and 58.8% of them had arsenic above 10, and 50 μg l - 1 , respectively. The groundwater samples from all 21 villages in Sagarpara GP contained arsenic above 50 μg l - 1 . In our preliminary clinical survey across the 21 villages, 3,302 villagers were examined and 679 among them (20.6%) were registered with arsenical skin lesions. A total of 850 biological samples (hair, nail and urine) were analysed from the affected villages and, on average, 85% of them contained arsenic above the normal level. Thus, many people of Sagarpara might be sub-clinically affected. Our data was compared with the international one to estimate population in Sagarpara GP at risk from arsenical skin lesions and cancer. Proper watershed management and economical utilization of available surface water resources along with the villagers' participation is urgently required to combat the present arsenic crisis.

Significance of private water supply wells in a rural Nevada area as a route of exposure to aqueous arsenic

Abstract: In many rural areas domestic drinking water needs are met by a mixture of public water supplies and private water supplies. Private supplies are not subject to the regulations and management requirements of the Safe Drinking Water Act (SDWA). Amendments to the SDWA recently lowered the standard for arsenic from 50 to 10ppb in public water supplies (effective in 2006). Churchill County, Nevada, has approximately 25,000 residents. Slightly more than half (13,500) rely on private domestic wells for water supply. Ample data and media publicity about high arsenic concentrations in water supplies and a federally led investigation of a leukaemia cluster suggested that residents of the county would be aware that arsenic concentrations in private wells were highly likely to exceed the 10ppb standard. A survey carried out in 2002 showed that a majority of respondents (72%) consumed water from private wells and among them a minority (38%) applied treatment. Maximum, median and minimum concentrations of arsenic from all samples (n ¼ 351) were 2,100, 26 and ,3ppb, respectively. Seventy-four per cent of all samples exceeded 10ppb. A majority (87%) of those who applied treatment consumed tap water. The relatively low rate of application of treatment suggested that these rural residents did not recognize that consumption could have associated health risks. However, those who applied treatment were ,0.3 times as likely to be consuming water with . 10ppb arsenic than those who consumed water that was not treated. In areas where concentrations of arsenic have been demonstrated to be high, it may be important to conduct a focused educational effort for private well owners to ensure that they take the steps needed to assess and reduce risks associated with contaminants found in tap water, including arsenic. An educational effort could include promoting sampling efforts to determine the magnitude of arsenic concentrations, explaining the risk associated with arsenic consumption and providing information about choices for home treatment systems that are likely to be effective in removing arsenic. This may be especially important in rural areas where

Contrasting occurrence of Chromobacterium violaceum in tropical drinking water springs of Uganda.

Abstract: Occurrence of Chromobacterium violaceum in six protected drinking water springs in Uganda was investigated. C. violaceum showed a contrasting occurrence, which was independent of human impact as assessed by faecal pollution indicators. It was isolated from two springs (S1 and S2) that were located close to each other (3km) but not in the rest. In S1 C. violaceum was continuously detected, in concentrations ranging from 6 to 270cfu 100ml 21 , while in S2 it was detected on only one sampling occasion. C. violaceum was never detected in the investigated upper soil layers (down to 15cm) in the immediate surroundings (50m radius) of the springs, despite continued isolation of faecal indicators. The results of the study indicate that C. violaceum may not be ubiquitous in spring water, but could occur in significant numbers in particular potable groundwaters as an autochthonous member.

Comparison of two methods for evaluating the quality of stored drinking water in Abidjan, Cote d'Ivoire, and review of other comparisons in the literature

Abstract: Membrane filtration, multiple tube fermentation (the standard methods) and Colilert are techniques available for assessing drinking water quality, but there are no published comparisons of Colilert to standard methods in a developing country laboratory. We reviewed the published literature on Colilert and standard methods and conducted a study to compare Colilert with membrane filtration for the detection and enumeration of total coliforms and fecal coliforms (Escherichia coli bacteria) using 35 stored drinking water samples from households in Abidjan, Cote d'lvoire. Our study results are consistent with previous published studies conducted in developed countries. Results from Colilert and membrane filtration correlated for both total coliforms (r2 = 0.81) and E. coli (r2 = 0.93). Colilert is an acceptable method to measure the presence and quantity of coliforms in water samples in a developing country setting.

Evaluation of microbiological quality of coastal waters in Greece

Abstract: To evaluate the microbiological water quality of bathing sites along the Achaia coastline (south western Greece), a survey was conducted to determine the concentration of faecal bacterial and phage indicators as well as the presence of human viruses. Seawater samples (234) were collected from nine bathing sites on the Achaia coastline and were analysed for the presence of: total coliforms, faecal coliforms, faecal streptococci, Escherichia coli, somatic coliphages, F-RNA bacteriophages, bacteriophages infecting Bacteroides fragilis, enteroviruses, adenoviruses and hepatitis A viruses. Most of the bacteriological analysis results were in accordance with the European Union standards. In all sites, bacteriophages were detected occasionally. Enteroviruses and adenoviruses were detected in 24 samples (10.26%) and 37 samples (15.81%) respectively. No samples were positive for the presence of hepatitis A virus. The overall data indicates that bathing sites are impacted by human faecal material. Both bacterial indicators and phages have low predictive capability for the presence of human viruses in coastal waters. None of the environmental parameters analysed was strongly related to the presence of the indicator organisms and viruses. Appropriate and effective administrative measures that should be taken into account may be considered in order to improve water quality and reduce public health risk.

A methodology for the evaluation of disinfection technologies

Abstract: There are several concerns associated with the use of chlorine for potable water disinfection These are the resistance of certain pathogens, the formation of toxic disinfection by-products and the adverse effects on aesthetic water quality Owing to these concerns the water industry is continually reviewing alternative disinfection technologies A methodology has been devised that will aid the water industry in evaluating the potential of these technologies The methodology uses seven criteria to evaluate the technologies, these are: inactivation efficiency, disinfection byproduct (DBP) formation, toxicity, aesthetic water quality, cost, scalability and residual maintenance Each criterion is assessed by associated questions in order of importance in accordance with a protocol The criteria are evaluated using UK water quality regulations as standards Ultraviolet (UV) disinfection was used as an example to demonstrate the methodology UV was shown to meet all the criteria apart from the provision of a residual disinfectant Several other disinfection technologies were evaluated using the methodology Direct electrochemical disinfection and mixed oxidant generators were identified as having the most potential for replacing chlorination

Serological responses to Cryptosporidium antigens among women using riverbank-filtered water, conventionally filtered surface water and groundwater in Hungary.

Abstract: We compared serological responses to Cryptosporidium parvum antigens using surplus sera from females undergoing routine screening for pregnancy from three counties in Hungary where bank-filtered surface water, conventionally filtered and disinfected surface water, and groundwater from either a karst or confined aquifer are commonly used for drinking water The primary purpose was to determine whether the prevalence and intensity of serological responses, indicators of prior Cryptosporidium infection were similar for these populations Women using groundwater from a confined aquifer had significantly lower mean serological responses for both the 15/17-kDa and 27-kDa (p < 00001) antigen groups than women using conventionally filtered and disinfected surface water or karst well water This is suggestive of less frequent infections Women using bank-filtered water also had lower mean responses for both antigen groups Among women using bank-filtered water, the mean intensity of response for both antigen groups was almost one-third of the mean response observed for women using conventionally filtered and disinfected surface water These findings suggest that riverbank filtration may be an effective alternative to conventional treatment for reducing Cryptosporidium exposures and infection from surface drinking water sources