scholarly journals Sensitivity of quantitative microbial risk assessments to assumptions about exposure to multiple consumption events per day

2014 ◽  
Vol 12 (4) ◽  
pp. 727-735 ◽  
Author(s):  
N. Van Abel ◽  
E. J. M. Blokker ◽  
P. W. M. H. Smeets ◽  
J. S. Meschke ◽  
G. J. Medema
Keyword(s):  
Drinking Water ◽  
Tap Water ◽  
Daily Intake ◽  
Risk Assessments ◽  
Multiple Time ◽  
Risk Of Infection ◽  
Short Term ◽  
Microbial Risk ◽  
Contamination Events ◽  
The Impact

Quantitative microbial risk assessments (QMRAs) of contaminated drinking water usually assume the daily intake volume is consumed once a day. However, individuals could consume water at multiple time points over 1 day, so the objective was to determine if the number of consumption events per day impacted the risk of infection from Campylobacter jejuni during short-term contamination events. A probabilistic hydraulic and risk model was used to evaluate the impact of multiple consumption events as compared to one consumption event on the health risk from the intake of contaminated tap water. The fraction of the population that experiences greater than 10−4 risk of infection per event at the median dose was 6.8% (5th–95th percentile: 6.5–7.2%) for one consumption event per day, 18.2% (5th–95th: 17.6–18.7%) for three consumption events per day, and 19.8% (5th–95th: 14.0–24.4%) when the number of consumption events varied around 3.49 events/day. While the daily intake volume remained consistent across scenarios, the results suggest that multiple consumption events per day increases the probability of infection during short-term, high level contamination events due to the increased coincidence of a consumption event during the contamination peak. Therefore, it will be important to accurately characterize this parameter in drinking water QMRAs.

scholarly journals Comparing probabilistic microbial risk assessments for drinking water against daily rather than annualised infection probability targets

2009 ◽  
Vol 7 (4) ◽  
pp. 535-543 ◽  
Author(s):  
R. S. Signor ◽  
N. J. Ashbolt
Keyword(s):  
Drinking Water ◽  
Disease Outbreaks ◽  
Assessment Process ◽  
Risk Assessments ◽  
Safe Drinking Water ◽  
Short Term ◽  
Management Planning ◽  
Microbial Risk ◽  
Risk Levels ◽  
Waterborne Pathogen

Some national drinking water guidelines provide guidance on how to define ‘safe’ drinking water. Regarding microbial water quality, a common position is that the chance of an individual becoming infected by some reference waterborne pathogen (e.g. Cryptsporidium) present in the drinking water should <10−4 in any year. However the instantaneous levels of risk to a water consumer vary over the course of a year, and waterborne disease outbreaks have been associated with shorter-duration periods of heightened risk. Performing probabilistic microbial risk assessments is becoming commonplace to capture the impacts of temporal variability on overall infection risk levels. A case is presented here for adoption of a shorter-duration reference period (i.e. daily) infection probability target over which to assess, report and benchmark such risks. A daily infection probability benchmark may provide added incentive and guidance for exercising control over short-term adverse risk fluctuation events and their causes. Management planning could involve outlining measures so that the daily target is met under a variety of pre-identified event scenarios. Other benefits of a daily target could include providing a platform for managers to design and assess management initiatives, as well as simplifying the technical components of the risk assessment process.

scholarly journals Evaluation of Minerals Content of Drinking Water in Malaysia

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Azrina Azlan ◽  
Hock Eng Khoo ◽  
Mohd Aizat Idris ◽  
Amin Ismail ◽  
Muhammad Rizal Razman
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Mineral Water ◽  
Tap Water ◽  
Fluoride Concentration ◽  
Daily Intake ◽  
Peninsular Malaysia ◽  
Mineral Water Sample ◽  
Geographical Locations ◽  
Iron And Manganese

The drinking and mineral water samples obtained from different geographical locations had concentrations of the selected minerals lower than the standard limits, except for manganese, arsenic, and fluoride. The concentrations of manganese and arsenic in two mineral water samples were slightly higher than the standard international recommended limits. One mineral water sample had a fluoride concentration higher than the standard limits, whereas manganese was not detected in nine drinking and mineral water samples. Most of the selected minerals found in the tap water samples were below the international standard limits, except for iron and manganese. The concentrations of iron and manganese in the tap water samples were higher than the standard limits, which were obtained from one and three of the studied locations, respectively. The potable water obtained from various manufacturers and locations in Peninsular Malaysia is safe for consumption, as the minerals concentrations were below the standard limits prescribed by the Malaysian Food Regulations of 1985. The data obtained may also provide important information related to daily intake of these minerals from drinking water.

The impact of investment on drinking water quality in rural China

2017 ◽  
Vol 9 (2) ◽  
pp. 255-269
Author(s):  
Ai Yue ◽  
Yaojiang Shi ◽  
Renfu Luo ◽  
Linxiu Zhang ◽  
Natalie Johnson ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Rural Areas ◽  
Tap Water ◽  
Rural China ◽  
Ordinary Least Squares ◽  
Content Type ◽  
Representative Data ◽  
Nationally Representative ◽  
The Impact

Purpose Although access to safe drinking water is one of the most important health-related infrastructure programs in the world, drinking water remains a large problem in China today, especially in rural areas. Despite increased government investment in water resource protection and management, there is still an absence of academic studies that are able to document what path the investment has taken and whether it has had any tangible impact. The purpose of this paper is to analyze the impact of drinking water investment on drinking water in China. Design/methodology/approach The authors make use of nationally representative data from 2005 and 2012 to measure the impact of drinking water investment among 2,028 rural households in 101 villages across five provinces. Both ordinary least squares regression and probit regression are used to analyze the correlates and the impact of drinking water investment. Findings The authors demonstrate that water quality was likely a significant problem in 2004 but that China’s investment into drinking water appears to have resulted in initial improvements during the study period. The authors show that the most significant change came about in terms of hardware: villages that received more drinking water investment now have more piped tap water and more access to water treatment infrastructure (disinfecting and filtering facilities). High rates of rural resident satisfaction with drinking water suggest the effects of drinking water investment are being felt at the village level. Originality/value To the authors’ knowledge, this is the first empirical study on drinking water investment over time in rural China using nationally representative data.

scholarly journals Impacts of temperature alteration on the drinking water quality stored in plastic bottles

2021 ◽  
Vol 11 (10) ◽  
Author(s):  
Abdelkader T. Ahmed ◽  
Mohammed Emad ◽  
Mohammed A. Bkary
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Tap Water ◽  
Research Work ◽  
Bottled Water ◽  
Physiochemical Parameters ◽  
Heating Water ◽  
Long Time ◽  
The Impact ◽  
Concentration Levels

AbstractMany people prefer to drink bottled water instead off the tap water. The bottled water is stored in the plastic bottles sometimes for long time. These plastic bottles might leach out some harmful materials into the water especially when exposed to temperature alteration, which may affect human health. This research work focused on investigating the effect of changing temperature on the bottled water quality. The work studied the effect of heating water in plastic bottles by sun, oven, and microwave. The study included also the impact of cooling and freezing the bottled waters. Results showed that temperature alterations caused changes in some physicochemical properties of bottled waters such as decreasing the values of pH and TDS and increasing levels of fluoride and chloride. In addition, the concentration levels of some physiochemical parameters exceeded the permissible values for drinking water. With temperature alterations, all levels of heavy metals in bottled waters were minimal except some small concentrations of copper and zinc. Results confirmed also differences in behavior between the bottled water brands exposed to the same temperature alterations. Heating bottled waters above 50 °C is alarming problem on the water quality. This is because above this degree, many alternations were observed in the water content. The outcomes of this work are useful for improving the current legislation on bottled waters and their storage.

Guidelines for the safe use of wastewater in agriculture: revisiting WHO guidelines

2004 ◽  
Vol 50 (2) ◽  
pp. 31-38 ◽  
Author(s):  
R.M. Carr ◽  
U.J. Blumenthal ◽  
D. Duncan Mara
Keyword(s):  
Health Care ◽  
Drinking Water ◽  
Relevant Information ◽  
Epidemiological Studies ◽  
Risk Assessments ◽  
Who Guidelines ◽  
Microbial Risk ◽  
Scarce Resources ◽  
Health Measures ◽  
Hygiene Promotion

The use of wastewater in agriculture is occurring more frequently because of water scarcity and population growth. Often the poorest households rely on this resource for their livelihood and food security needs. However, there are negative health implications of this practice that need to be addressed. WHO developed Guidelines for the Safe Use of Wastewater in Agriculture in 1989. The Guidelines are currently being revised based on new data from epidemiological studies, quantitative microbial risk assessments and other relevant information. WHO guidelines must be practical and offer feasible risk management solutions that will minimize health threats and allow for the beneficial use of scarce resources. To achieve the greatest impact on health, guidelines should be implemented with other health measures such as: health education, hygiene promotion, provision of adequate drinking water and sanitation, and other health care measures.

Thames Water's Experiences with Cryptosporidium

1991 ◽  
Vol 24 (2) ◽  
pp. 21-26 ◽  
Author(s):  
Madeline Poulton ◽  
Jennifer Colbourne ◽  
P. J. Dennis
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Agricultural Land ◽  
Sewage Treatment ◽  
Medical Advice ◽  
Expert Committee ◽  
Cryptosporidium Oocysts ◽  
Pass Through ◽  
Contamination Events ◽  
The Impact

In February 1989 an outbreak of waterborne cryptosporidiosis associated with contaminated surface water in the upper Thames catchment was identified. Less than 0.01% of the population suffered symptoms sufficient for them to seek medical advice. Nevertheless, the impact of the outbreak on the community and the water undertakers was considerable, and an expert committee was appointed by the Secretary of State for Health to advise on research and measures to control the disease and prevent future waterborne outbreaks. One of the committee's interim recommendations was for the gathering of information on the occurrence of cryptosporidium oocysts in the aquatic environment particularly sources used for abstraction and production of drinking water. The results of monitoring in the River Thames catchment will be discussed particularly in light of observations that peak contamination events occur in rivers which pass through agricultural land but do not receive discharges from sewage treatment works.

scholarly journals The Price of Fame: The Impact of Stimulus Familiarity on Proactive Interference Resolution

2011 ◽  
Vol 23 (4) ◽  
pp. 816-831 ◽  
Author(s):  
Ranjani Prabhakaran ◽  
Sharon L. Thompson-Schill
Keyword(s):  
Proactive Interference ◽  
Memory Retrieval ◽  
Recognition Task ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Short Term ◽  
Stimulus Familiarity ◽  
Resolution Processes ◽  
The Impact

Interference from previously learned information, known as proactive interference (PI), limits our memory retrieval abilities. Previous studies of PI resolution have focused on the role of short-term familiarity, or recency, in causing PI. In the present study, we investigated the impact of long-term stimulus familiarity on PI resolution processes. In two behavioral experiments and one event-related fMRI experiment, long-term familiarity was manipulated through the use of famous and nonfamous stimuli, and short-term familiarity was manipulated through the use of recent and nonrecent probe items in an item recognition task. The right middle frontal gyrus demonstrated greater sensitivity to famous stimuli, suggesting that long-term stimulus familiarity plays a role in influencing PI resolution processes. Further examination of the effect of long-term stimulus familiarity on PI resolution revealed a larger behavioral interference effect for famous stimuli, but only under speeded response conditions. Thus, models of memory retrieval—and of the cognitive control mechanisms that guide retrieval processes—should consider the impact of and interactions among sources of familiarity on multiple time scales.

scholarly journals Quantitative microbial risk assessment of distributed drinking water using faecal indicator incidence and concentrations

2007 ◽  
Vol 5 (S1) ◽  
pp. 131-149 ◽  
Author(s):  
J. Hein M. van Lieverloo ◽  
E. J. Mirjam Blokker ◽  
Gertjan Medema
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water System ◽  
Quantitative Microbial Risk Assessment ◽  
Concentration Data ◽  
Faecal Contamination ◽  
Microbial Risk ◽  
Contamination Events ◽  
Very High

Quantitative Microbial Risk Assessments (QMRA) have focused on drinking water system components upstream of distribution to customers, for nominal and event conditions. Yet some 15—33% of waterborne outbreaks are reported to be caused by contamination events in distribution systems. In the majority of these cases and probably in all non-outbreak contamination events, no pathogen concentration data was available. Faecal contamination events are usually detected or confirmed by the presence of E.coli or other faecal indicators, although the absence of this indicator is no guarantee of the absence of faecal pathogens. In this paper, the incidence and concentrations of various coliforms and sources of faecal contamination were used to estimate the possible concentrations of faecal pathogens and consequently the infection risks to consumers in event-affected areas. The results indicate that the infection risks may be very high, especially from Campylobacter and enteroviruses, but also that the uncertainties are very high. The high variability of pathogen to thermotolerant coliform ratios estimated in environmental samples severely limits the applicability of the approach described. Importantly, the highest ratios of enteroviruses to thermotolerant coliform were suggested from soil and shallow groundwaters, the most likely sources of faecal contamination that are detected in distribution systems. Epidemiological evaluations of non-outbreak faecal contamination of drinking water distribution systems and thorough tracking and characterisation of the contamination sources are necessary to assess the actual risks of these events.

Quantitative microbial risk assessments for drinking water facilities: evaluation of a range of treatment strategies

2019 ◽  
Vol 5 (11) ◽  
pp. 1943-1955
Author(s):  
Joshua G. Elliott ◽  
Liz Taylor-Edmonds ◽  
Robert C. Andrews
Keyword(s):  
Drinking Water ◽  
Treatment Strategies ◽  
Risk Assessments ◽  
Microbial Risk

Impact of treatment on pathogen risk.

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