Arsenic exposure in drinking water: an unrecognized health threat in Peru.

OBJECTIVE: To assess the extent of arsenic contamination of groundwater and surface water in Peru and, to evaluate the accuracy of the Arsenic Econo-Quick(™) (EQ) kit for measuring water arsenic concentrations in the field. METHODS: Water samples were collected from 151 water sources in 12 districts of Peru, and arsenic concentrations were measured in the laboratory using inductively-coupled plasma mass spectrometry. The EQ field kit was validated by comparing a subset of 139 water samples analysed by laboratory measurements and the EQ kit. FINDINGS: In 86% (96/111) of the groundwater samples, arsenic exceeded the 10 µg/l arsenic concentration guideline given by the World Health Organization (WHO) for drinking water. In 56% (62/111) of the samples, it exceeded the Bangladeshi threshold of 50 µg/l; the mean concentration being 54.5 µg/l (range: 0.1-93.1). In the Juliaca and Caracoto districts, in 96% (27/28) of groundwater samples arsenic was above the WHO guideline; and in water samples collected from the section of the Rímac river running through Lima, all had arsenic concentrations exceeding the WHO limit. When validated against laboratory values, the EQ kit correctly identified arsenic contamination relative to the guideline in 95% (106/111) of groundwater and in 68% (19/28) of surface water samples. CONCLUSION: In several districts of Peru, drinking water shows widespread arsenic contamination, exceeding the WHO arsenic guideline. This poses a public health threat requiring further investigation and action. For groundwater samples, the EQ kit performed well relative to the WHO arsenic limit and therefore could provide a vital tool for water arsenic surveillance.

More than a drop in the bucket: decentralized membrane-based drinking water refill stations in southeast Asia.

Decentralized membrane-based water treatment and refill stations represent a viable and growing business model in Southeast Asia, which rely upon the purchase of water from refill stations by consumers. This feature article discusses these water treatment and refill stations, including the appropriateness of the technology, the suitability of the business models employed, and the long-term environmental and operational sustainability of these systems. We also provide an outlook for the sector, highlighting key technical challenges that need to be addressed in order to improve the capacity of these systems, such that they can become an effective and financially viable solution.

Water flows, energy demand, and market analysis of the informal water sector in Kisumu, Kenya.

In rapidly growing urban areas of developing countries, infrastructure has not been able to cope with population growth. Informal water businesses fulfill unmet water supply needs, yet little is understood about this sector. This paper presents data gathered from quantitative interviews with informal water business operators (n=260) in Kisumu, Kenya, collected during the dry season. Sales volume, location, resource use, and cost were analyzed by using material flow accounting and spatial analysis tools. Estimates show that over 76% of the city's water is consumed by less than 10% of the population who have water piped into their dwellings. The remainder of the population relies on a combination of water sources, including water purchased directly from kiosks (1.5 million m3 per day) and delivered by hand-drawn water-carts (0.75 million m3 per day). Energy audits were performed to compare energy use among various water sources in the city. Water delivery by truck is the highest per cubic meter energy demand (35 MJ/m3), while the city's tap water has the highest energy use overall (21,000 MJ/day). We group kiosks by neighborhood and compare sales volume and cost with neighborhood-level population data. Contrary to popular belief, we do not find evidence of price gouging; the lowest prices are charged in the highest-demand low-income area. We also see that the informal sector is sensitive to demand, as the number of private boreholes that serve as community water collection points are much larger where demand is greatest.

Calicivirus removal in a membrane bioreactor wastewater treatment plant.

To evaluate membrane bioreactor wastewater treatment virus removal, a study was conducted in southwest France. Samples collected from plant influent, an aeration basin, membrane effluent, solid sludge, and effluent biweekly from October 2009 to June 2010 were analyzed for calicivirus (norovirus and sapovirus) by real-time reverse transcription-PCR (RT-PCR) using extraction controls to perform quantification. Adenovirus and Escherichia coli also were analyzed to compare removal efficiencies. In the influent, sapovirus was always present, while the norovirus concentration varied temporally, with the highest concentration being detected from February to May. All three human norovirus genogroups (GI, GII, and GIV) were detected in effluent, but GIV was never detected in effluent; GI and GII were detected in 50% of the samples but at low concentrations. In the effluent, sapovirus was identified only once. An adenovirus titer showing temporal variation in influent samples was identified only twice in effluent. E. coli was always below the limit of detection in the effluent. Overall, the removal of calicivirus varied from 3.3 to greater than 6.8 log units, with no difference between the two main genogroups. Our results also demonstrated that the viruses are blocked by the membrane in the treatment plant and are removed from the plant as solid sludge.

Modeling risk categories to predict the longitudinal prevalence of childhood diarrhea in Indonesia.

We present an innovative approach for analyzing diarrheal prevalence data that uses latent variables to model the relationships between multiple, interdependent environmental risk factors, and socioeconomic mediators. This strategy was applied to elucidate diarrheal longitudinal prevalence risk factors in children 1-4 years of age in low-income areas of Jakarta, Indonesia. Through a prospective cohort study, we identified 257 children who had at least one episode of diarrhea. At the onset of the study, we collected responses to 44 indicators, covering a wide range of previously identified diarrhea risk factors, including demographic and socioeconomic factors. We used exploratory factor analysis to uncover four latent categories of risk factors and their respective indicators from the initial pool of 44 indicators. Thereafter, we used structural equation modeling to model the relationships between the four risk categories and diarrheal longitudinal prevalence, controlling for socioeconomic and demographic covariates. Our final model elucidated several pathways to longitudinal diarrheal prevalence. Most notably, poverty exerts its effect on increased diarrheal prevalence via dual pathways: poor household hygiene and food quality, controlling for covariates. Implications of this and other findings for disease control in Jakarta are discussed.

Relationship between use of water from community-scale water treatment refill kiosks and childhood diarrhea in Jakarta.

In developing countries, safe piped drinking water is generally unavailable, and bottled water is unaffordable for most people. Purchasing drinking water from community-scale decentralized water treatment and refill kiosks (referred to as isi ulang depots in Indonesia) is becoming a common alternative. This study investigates the association between diarrhea risk and community-scale water treatment and refill kiosk. We monitored daily diarrhea status and water source for 1,000 children 1-4 years of age in Jakarta, Indonesia, for up to 5 months. Among children in an urban slum, rate of diarrhea/1,000 child-days varied significantly by primary water source: 8.13 for tap water, 3.60 for bottled water, and 3.97 for water kiosks. In multivariable Poisson regression analysis, diarrhea risk remained significantly lower among water kiosk users (adjusted rate ratio [RR] = 0.49, 95% confidence interval [CI] = 0.29-0.83) and bottled water users (adjusted RR = 0.45, 95% CI = 0.21-0.97), compared with tap water users. In a peri-urban area, where few people purchased from water kiosk (N = 28, 6% of total population), diarrhea rates were lower overall: 2.44 for well water, 1.90 for bottled water, and 2.54 for water kiosks. There were no significant differences in diarrhea risk for water kiosk users or bottled water users compared with well water users. Purchasing water from low-cost water kiosks is associated with a reduction in diarrhea risk similar to that found for bottled water.