Daily Archives: November 16, 2012

Mineral pot filters effective for bacteria, virus, and protozoa removal…

Brown J, Chai R, Wang A, Sobsey MD. Microbiological effectiveness of mineral pot filters in cambodia. Environ Sci Techno. 2012 Nov 6;46(21):12055-61. doi: 10.1021/es3027852. Epub  2012 Oct 24.

Mineral pot filters (MPFs) are household water treatment (HWT) devices that are manufactured and distributed by the private sector, with millions of users in Southeast Asia. Their effectiveness in reducing waterborne microbes has not been previously investigated. We purchased three types of MPFs available on the Cambodian market for systematic evaluation of bacteria, virus, and protozoan surrogate microbial reduction in laboratory challenge experiments following WHO recommended performance testing protocols. Results over the total 1500 L testing period per filter indicate that the devices tested were highly effective in reducing Esherichia coli (99.99%+), moderately effective in reducing bacteriophage MS2 (99%+), and somewhat effective against Bacillus atrophaeus, a spore-forming bacterium we used as a surrogate for protozoa (88%+). Treatment mechanisms for all filters included porous ceramic and activated carbon filtration. Our results suggest that these commercially available filters may be at least as effective against waterborne pathogens as other, locally available treatment options such as ceramic pot filters or boiling. More research is needed on the role these devices may play as interim solutions to the problem of unsafe drinking water in Cambodia and globally.


SODIS effective for Cryptosporidium…

Gómez-Couso H, Fontán-Sainz M, Navntoft C, Fernández-Ibáñez P, Ares-Mazás E. Comparison of different solar reactors for household disinfection of drinking water in developing countries: evaluation of their efficacy in relation to the waterborne enteropathogen Cryptosporidium parvum. Trans R Soc Trop Med Hyg. 2012 Nov;106(11):645-52. doi: 10.1016/j.trstmh.2012.07.014. Epub  2012 Sep 29.

Solar water disinfection (SODIS) is a type of treatment that can significantly improve the microbiological quality of drinking water at household level and therefore prevent waterborne diseases in developing countries. Cryptosporidium parvum is an obligate protozoan parasite responsible for the diarrhoeal disease cryptosporidiosis in humans and animals. Recently, this parasite has been selected by the WHO as a reference pathogen for protozoan parasites in the evaluation of household water treatment options. In this study, the field efficacy of different static solar reactors [1.5 l transparent plastic polyethylene terephthalate (PET) bottles as well as 2.5 l borosilicate glass and 25 l methacrylate reactors fitted with compound parabolic concentrators (CPC)] for solar disinfection of turbid waters experimentally contaminated with C. parvum oocysts was compared. Potential oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. The results demonstrate that static solar reactors fitted with CPCs are an excellent alternative to the conventional SODIS method with PET bottles. These reactors improved the efficacy of the SODIS method by enabling larger volumes of water to be treated and, in some cases, the C. parvum oocysts were rendered totally unviable, minimising the negative effects of turbidity.

Unsafe water, poor sanitation in Nepal…

Aryal KK, Joshi HD, Dhimal M, Singh SP, Dhakal P, Dhimal B, Bhusal CL. Environmental Burden of Diarrhoeal Diseases due to Unsafe Water Supply and Poor Sanitation Coverage in Nepal. J Nepal Health Res Counc. 2012 May;10(21):125-9.

Background: Unsafe water and poor sanitation are major contributing factors of diarrhoea. Most of the water supply systems in urban and rural area of Nepal do not have basic water treatment facilities. This has resulted in frequent reports of fecal contamination in drinking water and outbreaks of waterborne diseases. The purpose of this study was to find out the burden of diarrhoeal diseases at different scenario of water supply system and sanitation status in Nepalese context.

Methods: A cross-sectional study was conducted in four different districts of Nepal analyzing six different scenarios based on availability of water supply and sanitation status. Village Development Committees (VDCs) and community selection was made purposively and 360 households, 60 from each scenario were selected conveniently to achieve the required number. Within the selected household, the head of the household or any member above 18 years of age was interviewed using a structured questionnaire. Observation was done for toilet and water sources besides questionnaire method.

Results: Incidence of diarrhoea per 1000 population was found to be the highest in scenario-IV (Spring without toilet) with 204.89 followed by scenario-VI (Tube well without toilet) with 145.30, while it was less in scenario-I (Tap water with toilet) with 46.05. Accordingly, the burden of disease (YLD) was also found to be the highest in scenario-IV and the lowest in scenario-I. Most of the households didn’t treat water before drinking. Hand washing practice was found to be more than 90% regardless of toilet availability.

Conclusions: The greater risk of acquiring diarrhoeal disease and higher burden of disease in situation of unprotected water source and absence of toilet shows that these are still important contributing factors for diarrhoeal disease in Nepal. Use of sanitary toilets and protected water source are the important measures for diarrhoeal disease prevention in Nepal.

More frequent toothbrushing, more milk, less presweetend cereal……what a suprise!

Chankanka O, Levy SM, Marshall TA, Cavanaugh JE, Warren JJ, Broffitt B, Kolker JL. The associations between dietary intakes from 36 to 60 months of age and primary dentition non-cavitated caries and cavitated caries. J Public Health Dent. 2012 Nov 8. doi: 10.1111/j.1752-7325.2012.00376.x.

OBJECTIVE: To examine risk factors for non-cavitated caries, as well as cavitated caries.

METHODS: Subjects were participants in the Iowa Fluoride Study cohort. Dietary data were collected at 36, 48, and 60 months old using 3-day dietary diaries, and a dental examination was conducted at about age 5. We compared the frequencies of dietary intakes of three groups: a) children having only d(1) caries (n = 41); b) children having only cavitated (d(2+) f) caries (n = 46); and c) children having both d(1) and d(2+) f caries (n = 49) with a forth group; d) those of caries-free children (n = 257).

RESULTS: Multinomial and binomial logistic regression was used, where the categorical outcome was based on the 4 caries groups, and the caries-free group was designated as the reference. In the final model, sevenvariables were associated with the caries outcome. Lower milk consumption frequency at meals and greater presweetened cereal consumption frequency at meals were significantly associated with a greater likelihood of being in the d(1) group. Greater regular soda pop consumption frequency and greater added sugar consumption frequency at snacks were significantly associated with being in the cavitated caries (d(2+) f and/or d(1) d(2+) f) groups. Lower socioeconomic status and less frequent toothbrushing increased the likelihood of being in the d(1) group.

CONCLUSIONS: The results suggest that different food and beverage categories are associated with being in the d(1) group compared with the cavitated caries groups. More frequent toothbrushing, greater milk consumption at meals, and avoiding presweetened cereal consumption at meals might reduce the risk of developing non-cavitated caries.

Cryptosporidium in Swiss drinking water….

Füchslin H, Egli T, Kötzsch S. Cryptosporidium spp. in drinking water. Swiss Med Wkly. 2012 Oct 4;142:0. doi: 10.4414/smw.2012.13683.

Abstract: In most rural areas and small communities in Switzerland the drinking water is supplied to the consumers after a minimum or even no treatment at all. However, it is just in these areas where drinking water from sources of agricultural activities can be contaminated by liquid manure and faeces of pasturing animals. The Swiss drinking water regulations are limited to the monitoring of E. coli, Enterococcus spp. and total plate counts only. Hence, resistant pathogens, as for example Cryptosporidium spp., remain unnoticed. During a drinking water survey, which lasted from June 2003 to December 2004, water samples were collected from 3 selected rural sites in Switzerland. The drinking water was investigated for Cryptosporidium spp., E. coli, Enterococcus spp., Clostridium perfringens and other parameters. In all samples oocysts of Cryptosporidium spp. were detected at elevated concentrations of up to 0.18 oocysts/l. Between 28% and 75% of the oocysts were found to be vital by the excystation method. Sampled oocysts collected from the three sites were subjected to genotyping and in one case the isolate was found to belong to the genotype of C. parvum. No evidence for increased incidents of diarrhoea in the past years was noted by local authorities.

Click here for full paper (fee).


Little change in global drought over the past 60 years…

J. Sheffield, E. Wood, M. Roderick. Little change in global drought over the past 60 years. Nature 491, 435–438. DOI: doi:10.1038/nature11575

Abstract: Drought is expected to increase in frequency and severity in the future as a result of climate change, mainly as a consequence of decreases in regional precipitation but also because of increasing evaporation driven by global warming. Previous assessments of historic changes in drought over the late twentieth and early twenty-first centuries indicate that this may already be happening globally. In particular, calculations of the Palmer Drought Severity Index (PDSI) show a decrease in moisture globally since the 1970s with a commensurate increase in the area in drought that is attributed, in part, to global warming. The simplicity of the PDSI, which is calculated from a simple water-balance model forced by monthly precipitation and temperature data, makes it an attractive tool in large-scale drought assessments, but may give biased results in the context of climate change. Here we show that the previously reported increase in global drought is overestimated because the PDSI uses a simplified model of potential evaporation that responds only to changes in temperature and thus responds incorrectly to global warming in recent decades. More realistic calculations, based on the underlying physical principles that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years. The results have implications for how we interpret the impact of global warming on the hydrological cycle and its extremes, and may help to explain why palaeoclimate drought reconstructions based on tree-ring data diverge from the PDSI-based drought record in recent years.

Click here for the full paper (fee).

Cocaine transformed during water chlorination…

González-Mariño I, Quintana JB, Rodríguez I, Sánchez-Méndez N, Cela R. Transformation of cocaine during water chlorination. Anal Bioanal Chem. 2012 Sep 30.

Abstract: The stability of cocaine and its two main human metabolites, benzoylecgonine and ecgonine methyl ester, in chlorine-containing waters has been investigated by direct injection of different reaction time aliquots in a liquid chromatograph (LC) coupled to a quadrupole-time-of-flight mass spectrometer (QTOF-MS). Factors potentially affecting cocaine degradation (the only compound showing a significant decrease in the preliminary study) were evaluated in detail by means of a Box-Behnken experimental design. Sample pH resulted to be the most important variable, increasing both the rate of chlorination-mediated reactions and the ester hydrolysis process. From these reactions, and due to the high mass accuracy measurements obtained with the QTOF system, four by-products could be positively identified: benzoylecgonine, norcocaine, norbenzoylecgonine and N-formylnorcocaine. Finally, their formation and cocaine degradation yields were assessed under chlorination experiments with two real surface water samples. In one of them, showing a low anthropogenic impact, benzoylecgonine and norcocaine were notably generated even after only 1 h of reaction, whereas at higher contact times also norbenzoylecgonine and N-formylnorcocaine could be determined with a lower yield. On the other hand, the second sample, with a higher organic matter content, consumed rapidly the chlorine, so that only benzoylecgonine was produced. These findings point out the convenience of monitoring the described transformation products, in addition to the precursor illicit drug, during drinking water production, taking into account that cocaine traces might be present in water catchments and particularly in areas with high population densities.