Pecologix Political Ecology Blotter » drinking

Risk of Gastrointestinal Illness Associated with the Consumption of Rainwater: A Systematic Review

A. Cherson — Wed, 14 Mar 2012 02:32:53 +0000

The collection of rainwater for human consumption is a practice well established in many parts of the world. Much of the research to date regarding this inexpensive and sustainable source has focused on its microbiological or chemical quality and there have been no reviews of epidemiological evidence regarding actual health risks associated with rainwater consumption. Electronic bibliographic databases were searched for epidemiological studies that attempted to quantify the risk of gastrointestinal disease linked to the consumption of harvested rainwater. Online databases were searched from the oldest date up to January 2011. Both observational and experimental studies were included. In addition, reference sections of key articles were searched and authors of previous studies were contacted where appropriate. Studies were assessed for relevance independently and in duplicate. Searches returned a total of 764 articles, 13 met inclusion criteria, 5 of these were outbreak reports, and 9 were studies of other design types. Pooled subgroup analysis suggests that rainwater is associated with reduced risk of illness compared to unimproved supplies (relative risk 0.57 95% CI 0.42, 0.77). There was no significant difference in risk in the pooled analysis of studies that compared rainwater to improved water supplies (relative risk 0.82 95% CI 0.38, 1.73). However, there was heterogeneity with one study showing an excess risk of campylobacteriosis. Classification of outbreak reports determined that 4 reports were “strongly associated with rainwater” while 1 report was “probably associated with rainwater”. We conclude that the evidence suggests that rainwater is safer than water from unimproved water supplies. Where feasible rainwater harvesting should be encouraged as a step toward achieving millennium development targets.

DOI: http://dx.doi.org/10.1021/es203351n

Climate change links to global expansion of harmful cyanobacteria

A. Cherson — Sat, 11 Feb 2012 15:29:11 +0000

Cyanobacteria are the Earth’s oldest (∼3.5 bya) oxygen evolving organisms, and they have had major impacts on shaping our modern-day biosphere. Conversely, biospheric environmental perturbations, including nutrient enrichment and climatic changes (e.g. global warming, hydrologic changes, increased frequencies and intensities of tropical cyclones, more intense and persistent droughts), strongly affect cyanobacterial growth and bloom potentials in freshwater and marine ecosystems. We examined human and climatic controls on harmful (toxic, hypoxia-generating, food web disrupting) bloom-forming cyanobacteria (CyanoHABs) along the freshwater to marine continuum. These changes may act synergistically to promote cyanobacterial dominance and persistence. This synergy is a formidable challenge to water quality, water supply and fisheries managers, because bloom potentials and controls may be altered in response to contemporaneous changes in thermal and hydrologic regimes. In inland waters, hydrologic modifications, including enhanced vertical mixing and, if water supplies permit, increased flushing (reducing residence time) will likely be needed in systems where nutrient input reductions are neither feasible nor possible. Successful control of CyanoHABs by grazers is unlikely except in specific cases. Overall, stricter nutrient management will likely be the most feasible and practical approach to long-term CyanoHAB control in a warmer, stormier and more extreme world.

DOI: http://dx.doi.org/10.1016/j.watres.2011.08.002

Cluster Randomized Controlled Trial of the Plastic BioSand Water Filter in Cambodia

A. Cherson — Wed, 18 Jan 2012 03:57:59 +0000

About half of the rural population of Cambodia lacks access to improved water; an even higher percentage lacks access to latrines. More than 35,000 concrete BioSand Water filters (BSF) have been installed in the country. However, the concrete BSF takes time to produce and weighs hundreds of pounds. A plastic BSF has been developed but may not perform to the same benchmarks established by its predecessor. To evaluate plastic BSF performance and health impact, we performed a cluster randomized controlled trial in 13 communities including 189 households and 1147 participants in the Angk Snoul district of Kandal Province from May to December 2008. The results suggest that villages with plastic BSFs had significantly lower concentrations of E. coli in drinking water and lower diarrheal disease (incidence rate ratio 0.41, 95% confidence interval: 0.24–0.69) compared to control villages. As one of the first studies on the plastic BSF in Cambodia, these are important findings, especially in a setting where the concrete BSF has seen high rates of continued use years after installation. The study suggests the plastic BSF may play an important role in scaling up the distribution/implementation of the BSF, potentially improving water quality and health in the region.

DOI: http://dx.doi.org/10.1021/es203114q

Development of a Mobile Water Disinfection Unit Powered by Renewable Energy

A. Cherson — Tue, 17 Jan 2012 00:28:09 +0000

Providing a water supply and the associated transportation of potable water is a considerable burden on recovery efforts following a natural disaster. To reduce this burden and meet the water requirements of a community, a low-maintenance, low-cost trailer-mounted water disinfection system has been developed that has the capability to provide potable water from local surface water bodies until the infrastructure is repaired. To achieve disinfection of contaminated surface water, the system uses a series of prefilters and an ultraviolet (UV) disinfection unit. The system is powered using a hybrid photovoltaic array and wind turbine system. To increase the storage capability and decrease the maintenance required by the system, traditional, relatively high-maintenance batteries have been replaced with an ultracapacitor to store the energy generated by the renewable energy component. The prototype system was field tested for several months. Tests conducted on the system included monitoring the energy generation and consumption of system components and verification of the disinfection capability by sampling various surface water bodies. The prototype performed as desired; however, during testing the PV array provided sufficient energy and the wind turbine was deemed redundant.

doi: http://dx.doi.org/10.1061/(ASCE)EY.1943-7897.0000045

Chemical compounds and toxicological assessments of drinking water stored in polyethylene terephthalate (PET) bottles: A source of controversy reviewed

A. Cherson — Mon, 09 Jan 2012 02:03:26 +0000

Formaldehyde, acetaldehyde and antimony are clearly related to migration from PET into water. However, several studies have shown other theoretically unexpected substances in bottled water. The origin of these compounds has not been clearly established (PET container, cap-sealing resins, background contamination, water processing steps, NIAS, recycled PET, etc.).

Here, we surveyed toxicological studies on PET-bottled water and chemical compounds that may be present therein. Our literature review shows that contradictory results for PET-bottled water have been reported, and differences can be explained by the wide variety of analytical methods, bioassays and exposure conditions employed.

http://dx.doi.org/10.1016/j.watres.2011.11.062

Decentralized Membrane Filtration System for Sustainable and Safe Drinking Water Supply in Low-Income Countries: Baseline Study

A. Cherson — Mon, 19 Dec 2011 19:49:35 +0000

Decentralized membrane filtration systems (DMFS) have the potential to supply safe drinking water in low-income countries (LICs) where centralized municipal water treatment is practically infeasible. This study aimed at applying an integrated bench-scale and field-testing approach to assess the sustainability of a DMFS in producing safe drinking water in LICs. The state-of-the-art DMFS employed in this study was capable of removing bacteria, surrogate parasites, and viruses at log⁡ reductions above 7, 5, and 4, respectively, from evaluated waters (n = 4). The technological sustainability of the DMFS was primarily affected by membrane fouling, and a linear correlation was found between the reversible/irreversible fouling rates of a miniature bench-scale system and those of the full-size DMFS caused by representative types of source waters. The total and irreversible fouling rates of the full-size DMFS were approximately 50% of those of the miniature system, regardless of the properties of the source waters. Similar quantitative relationships may be established between the fouling rates of the bench-scale system and those of other full-size DMFS. Overall, easy and cost-effective fouling control is warranted for sustainable application of DMFS in LICs, and bench-scale membrane testing serves as a potential screening tool for this purpose.

doi: http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0000433