A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies.

Background: Despite poor evidence of their effectiveness, colloidal silver and silver nanoparticles are increasingly being promoted for treating potentially contaminated drinking water in low income countries. Recently, however, concerns have been raised about the possible genotoxicity of particulate silver.

Objectives: The goal of this paper was to review the published mammalian in vivo genotoxicity studies using silver micro and nanoparticles.

Recreational Water and Infection: A Review of Recent Findings.

This paper reviews the latest evidence provided by epidemiological studies and quantitative microbial risk assessments (QMRAs) of infection risk from recreational water use. Studies for review were selected following a PubMed search for articles published between January 2010 and April 2014. Epidemiological studies show a generally elevated risk of gastrointestinal illness in bathers compared to non-bathers but often no clear association with water quality as measured by faecal indicator bacteria; this is especially true where study sites are impacted by non-point source pollution.

Hygiene and health: systematic review of handwashing practices worldwide and update of health effects.

Objective: To estimate the global prevalence of handwashing with soap and derive a pooled estimate of the effect of hygiene on diarrhoeal diseases, based on a systematic search of the literature.

Methods: Studies with data on observed rates of handwashing with soap published between 1990 and August 2013 were identified from a systematic search of PubMed, Embase and ISI Web of Knowledge. A separate search was conducted for studies on the effect of hygiene on diarrhoeal disease that included randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined.

Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: systematic review and meta-regression.

Objective: To assess the impact of inadequate water and sanitation on diarrhoeal disease in low- and middle-income settings.

Methods: The search strategy used Cochrane Library, MEDLINE & PubMed, Global Health, Embase and BIOSIS supplemented by screening of reference lists from previously published systematic reviews, to identify studies reporting on interventions examining the effect of drinking water and sanitation improvements in low- and middle-income settings published between 1970 and May 2013. Studies including randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined were eligible.

Burden of disease from inadequate water, sanitation and hygiene in low- and middle-income settings: a retrospective analysis of data from 145 countries.

Objective: To estimate the burden of diarrhoeal diseases from exposure to inadequate water, sanitation and hand hygiene in low- and middle-income settings and provide an overview of the impact on other diseases.

Methods: For estimating the impact of water, sanitation and hygiene on diarrhoea, we selected exposure levels with both sufficient global exposure data and a matching exposure-risk relationship. Global exposure data were estimated for the year 2012, and risk estimates were taken from the most recent systematic analyses.

Faecal indicator organism concentrations and catchment export coefficients in the UK.

Characterisation of faecal indicator organism (FIO) concentrations and export coefficients for catchments with particular combinations of land use and under specific climatic regimes is critical in developing models to predict daily loads and apportion sources of the microbial parameters used to regulate water quality. Accordingly, this paper presents a synthesis of FIO concentration and export coefficient data for the summer bathing season, with some comparative winter data, for 205 river/stream sampling points widely distributed across mainland UK. In terms of both geometric mean (GM) FIO concentrations and export coefficients (expressed as cfu km(-2) h(-1)), the results reveal (1) statistically significant elevations at high flow compared with base flow, with concentrations typically increasing by more than an order of magnitude and export coefficients by about two orders; (2) significantly higher values in summer than in winter under high-flow conditions; and (3) extremely wide variability between the catchments (e.

An attempt to quantify the health impacts of flooding in the UK using an urban case study.

Objectives: To quantify, so far as possible, the health effects of flooding in the UK to allow comparison between different flooding events.

Methods: The health effects resulting from flooding events were determined through an extensive literature search, where information existed to enable the quantification of these effects. Disability-adjusted life years (DALYs) were used to enable the comparison between different health impacts and different flood events and populations, using two sites subject to pluvial flooding in the Bradford area, UK.

The microbiological quality of seven large commercial private water supplies in the United Kingdom.

Some 1% of the UK population derives their potable water from 140,000 private water supplies (PWSs) regulated by Local Authorities. The overwhelming majority of these are very small domestic supplies serving a single property or a small number of properties. Treatment for such supplies is rudimentary or non-existent and their microbiological quality has been shown to be poor in every published study to date.

Faecal indicator organism concentrations in sewage and treated effluents.

The importance of faecal indicator organism (FIO) fluxes within drainage basins is increasing as the European Union (EU) Water Framework Directive and the United States Clean Water Act place requirements on regulators to manage point and diffuse sources of microbial pollution causing non-compliance (EU) or impairment (US) of receiving waters. Central to this management task is knowledge of the likely FIO concentrations in raw sewage and treated effluents, but few empirical data have been published in the peer-reviewed literature. Accordingly, this paper presents results for 1933 samples from 162 different sewage discharge sites in the UK and Jersey, which encompass 12 types of sewage-related discharge, representative of untreated sewage and primary-, secondary- and tertiary-treated effluents.

An attempt to estimate the global burden of disease due to fluoride in drinking water.

A study was conducted to examine the feasibility of estimating the global burden of disease due to fluoride in drinking water. Skeletal fluorosis is a serious and debilitating disease which, with the exception of one area in China, is overwhelmingly due to the presence of elevated fluoride levels in drinking water. The global burden of disease due to fluoride in drinking water was estimated by combining exposure-response curves for dental and skeletal fluorosis (derived from published data) with model-derived predicted drinking water fluoride concentrations and an estimate of the percentage population exposed.

Reply to comments on "Derivation of numerical values for the World Health Organization guidelines for recreational waters".

The contribution addressed reveals an optimistic design philosophy likely to systematically underestimate risk in epidemiologic studies into the health effects of bathing water exposures. The authors seem to recommend that data on the 'exposure' measure (i.e.

Water, sanitation and hygiene in developing countries: interventions and diarrhoea--a review.

We conducted a search to identify all English language papers (published between 1 January 1985 and 26 June 2003) with evidence on the effectiveness of water, sanitation and hygiene interventions in developing countries, in which diarrhoea morbidity in non-outbreak conditions was reported. A total of 39 studies were identified as relevant after an initial review of over 2000 titles. Data were extracted and, where possible, combined using meta-analysis to provide a summary estimate of the effectiveness of specific interventions, including water supply and water treatment.

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

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.

Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis.

Many studies have reported the results of interventions to reduce illness through improvements in drinking water, sanitation facilities, and hygiene practices in less developed countries. There has, however, been no formal systematic review and meta-analysis comparing the evidence of the relative effectiveness of these interventions. We developed a comprehensive search strategy designed to identify all peer-reviewed articles, in any language, that presented water, sanitation, or hygiene interventions.

Drinking-water nitrate, methemoglobinemia, and global burden of disease: a discussion.

On behalf of the World Health Organization (WHO), I have undertaken a series of literature-based investigations examining the global burden of disease related to a number of environmental risk factors associated with drinking water. In this article I outline the investigation of drinking-water nitrate concentration and methemoglobinemia. The exposure assessment was based on levels of nitrate in drinking water greater than the WHO guideline value of 50 mg/L.

Derivation of numerical values for the World Health Organization guidelines for recreational waters.

In April 2001, draft 'Guidelines' for safe recreational water environments were developed at a World Health Organization (WHO) expert consultation. Later the same month, these were presented and discussed at the 'Green Week' in Brussels alongside the on-going revision of the European Union Bathing Water Directive 76/160/EEC. The WHO Guidelines cover general aspects of recreational water management as well as define water quality criteria for various hazards.

Estimating the global burden of disease of mild mental retardation and cardiovascular diseases from environmental lead exposure.

The disease burden from exposure to lead resulting in mild mental retardation (due to IQ point decreases) and cardiovascular outcomes (due to increases in blood pressure) was estimated at a global level. Blood lead levels were compiled from the literature for 14 geographical regions defined by the World Health Organization according to location and adult and child mortality rates. Adjustments were applied to these levels, where appropriate, to account for recent changes relating to the implementation of lead-reduction programs and the lower levels seen in rural populations.

Estimating the burden of disease from water, sanitation, and hygiene at a global level.

We estimated the disease burden from water, sanitation, and hygiene at the global level taking into account various disease outcomes, principally diarrheal diseases. The disability-adjusted life year (DALY) combines the burden from death and disability in a single index and permits the comparison of the burden from water, sanitation, and hygiene with the burden from other risk factors or diseases. We divided the world's population into typical exposure scenarios for 14 geographical regions.

A review of the science behind drinking water standards for copper.

Copper is an essential element, being a vital component in several enzyme systems. Some intake, therefore, is necessary for human health. At high intakes, however, it can have toxic effects.

Uncertainties in risk assessment for the determination of drinking water pollutant concentrations: Cryptosporidium case study.

There is a growing acknowledgement of the need to recognise uncertainties in the estimation of waterborne risks. In this paper, the strength of the science available to characterise Cryptosporidium risks in drinking water is investigated, in particular the determination of oocyst concentrations at various points in the chain of water supply. A recently developed scientific quality audit framework is used as a tool to guide this investigation.

Faecal indicator impacts on recreational waters: budget studies and diffuse source modelling.

A series of investigations are underway which have quantified the contribution of faecal indicators delivered to nearshore coastal waters from the sewerage system and riverine inputs. Studies have been completed in Jersey, Staithes, Yorkshire, South Wales and the North-west. The research protocols have involved quantification of high and low flow faecal indicator delivery from the sewerage system and riverine sources as well as construction of nonpoint source models designed to predict faecal indicator delivery from diffuse, catchment sources.

Copper in drinking water--an investigation into possible health effects.

A study was carried out to examine the possible relationship between levels of copper in drinking water and the incidence of specified childhood liver complaints presenting at a major UK paediatric liver unit. Public drinking water supplies were generally found to have levels of copper which were well below the EC standard of 3,000 micrograms/l. In private supplies, a slightly greater number of samples were found to exceed the prescribed concentration; in one instance a value of 26,000 micrograms/l was recorded.

Health effects of white-water canoeing.

There is little quantitative information on the relation between water quality and disease attack rates after recreational activities in fresh water. We conducted a prospective cohort study to measure the health effects of white-water and slalom canoeing in two channels with different degrees of microbial contamination. Site A, fed by a lowland river, showed high enterovirus concentrations (arithmetic mean 198 pfu per 10 litre and moderate faecal coliform concentrations (geometric mean 285/dl); at site B, from an upland impoundment, all samples were free of enteroviruses and the geometric mean faecal coliform concentration was 22/dl.