WQRA HealthStream - Issue 59

HEALTH STREAM SEPTEMBER 2010 PAGE 1

Issue 59 Public Health Newsletter of Water Quality Research Australia September 2010 In this Issue: WA Catchment Access Inquiry 1 Car Windscreen Washer Fluid and 2 Legionnaires’ Disease Water Treatment for Influenza Viruses 4 News Items 5 From The Literature 7 Web Bonus Articles Arsenic Cancer Cyanobacteria Extreme Events Fluoride Obesity Perchlorate POU Treatment Rainwater Viruses Email List Details 20 Editor Martha Sinclair Assistant Editor Pam Hayes WQRA Internet Address: www.wqra.com.au A searchable Archive of Health Stream articles, literature summaries and news items is available via the WQRA Web page.

WA Catchment Access Inquiry The West Australian Legislative Council Standing Committee on Public Administration has completed an Inquiry into Recreation Activities within Public Drinking Water Source Areas. The results of the Inquiry are contained in a 162 page report tabled in the West Australian State Parliament on 22 September. The inquiry was established 12 months ago and gathered evidence from 193 written submissions and thirteen hearings, as well as visiting several dams and catchments in Western Australia and Queensland. The issue of public access to drinking water catchments has had a high profile in Western Australia since late 2007 when the Minister for Water Resources announced that the Logue Brook Dam (used for irrigation and public recreation) would be closed to public access so that it could be converted into a drinking water supply storage. A State election in September 2008 saw a change of government, the plan to use the Logue Brook Dam for drinking water was reversed and the dam was then reopened to public recreational access.

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WATER QUALITY RESEARCH AUSTRALIA


A number of lobby groups subsequently campaigned for a relaxation of access restrictions to existing drinking water catchments in the state, citing social and economic benefits that would arise from such changes. The Legislative Council then asked the Standing Committee on Public Administration to recommend what policy should be taken with regard to recreation access to catchment areas from the Perth hills to the south-west of the State. The Terms of Reference of the Inquiry were to investigate: • The social, economic and environmental values and costs of recreation access, where possible, to Perth hills and south west drinking water catchments, including the costs and benefits to public health, water quality, recreation, Indigenous culture and management options. • State, interstate and international legislation, policy and practice for recreation within public drinking water source areas, including information relating to population health benefits and impacts. • The range of community views on the value of water and recreation in public drinking water source areas. • The costs and benefits of alternative water quality management strategies and treatment for water catchments containing recreation. • Possible recreation sites or opportunities available outside the Perth hills and south west drinking water catchments.

The Inquiry Report contains 14 findings and 11 recommendations. The principle finding is that the use of public drinking water source areas for both recreation and drinking water is untenable as a result of: • the risk of human pathogens being introduced to drinking water; • the cumulative effect of human presence in the catchments having potentially adverse ecological impacts affecting water quality; and • the need to protect surplus desalinated water which is being stored in various catchment reservoirs. The Committee therefore recommended that there should be no increase in the amount of current recreational activity in the outer catchments of public drinking water source areas. The Committee recognised the social and economic value of

recreational activities on and near dams, and recommended continuation of current collaborative efforts between relevant government agencies to identify suitable water bodies for these purposes that are not used for drinking water supply. Recommendations were also made that by-laws relating to catchment protection should be strengthened and penalties for breaches increased. Under the Standing Orders of the West Australian Legislative Council, the State Government is required to respond to the Report within four months. The Report can be downloaded from: http://www.parliament.wa.gov.au/web/newwebparl.nsf/ iframewebpages/Committees+-+Reports Car Windscreen Washer Fluid and Legionnaires’ Disease Legionnaires’ disease is a type of pneumonia caused by infection of the lungs by bacteria of the genus Legionella. Infection is caused by inhalation of the bacteria in tiny water droplets from devices which generate water aerosols including air conditioning units, cooling towers, fountains, showers and spa baths. The majority of cases are caused by Legionella pneumophila, but several other Legionella species may also cause the infection. A less severe form of disease called Pontiac fever also results from Legionella infection. Only a minority of the cases of Legionnaires’ disease identified by health agencies are associated with outbreaks that can be traced to common infection source, while the majority appear to be individual, unrelated cases scattered throughout the community (sporadic cases). Recent research has highlighted an ever growing list of potential sources of Legionella infection including commercial car washes and industrial washing equipment (1). Now a study of sporadic Legionnaires’ disease cases in England and Wales has found a strong association with use of vehicles where the windscreen washing water did not contain added screenwash (2). The study was prompted by the findings of previous research which examined whether cases of sporadic Legionnaires’ disease occurring between 2001 and 2006 in England and Wales showed any association with the occupation of



the patient. It was found that the rate of sporadic disease cases was about 6 times higher among professional drivers (van, bus, taxi and heavy transport) than those employed in other occupations. The new case-control study was then carried out to investigate a range of exposures associated with driving or being a passenger in vehicles. Eligible cases in the study were people living in England and Wales who had been reported to the national surveillance system and had sporadic community-acquired Legionnaires’ disease with onset dates between 15 July 2008 and 9 March 2009. Cases with recent overseas travel, suspected nosocomial infection or links to a recognised outbreak were excluded. Those who had died or were unable to give informed consent were also excluded. Controls living in the same geographic area as a selected case were recruited by sequential digit dialling based on the telephone area code of the case. Attempts were made to recruit three controls per case, matched by age group (19-49 years, 50-69 years) and sex as well as area of residence. After initial contact by telephone, a postal questionnaire covering known risk factors such as smoking, underlying illness and shower use as well as vehicle-related exposures was sent to both cases and controls. Vehicle-related questions included distance and time travelled as a passenger or driver, time with windows open, time driven in urban, rural or industrial areas, and use of vehicle air-conditioning or air recirculation. Exposures were assessed for the two weeks prior to disease onset for cases or two weeks prior to questionnaire completion for controls. Data were also collected on vehicle type, manufacturer, age, service history, content of windscreen wiper fluid reservoir and social versus work-related travel. A total of 123 sporadic cases of Legionnaires’ disease were reported during the study period, and 107 were successfully contacted. Of these, 14 were excluded and the remaining 93 were sent questionnaires. A total of 75 completed questionnaires were returned (80.6% of 93). Recruitment of controls proved to be difficult with 56% of those contacted being ineligible and only

41% of eligible people (117/284) agreeing to be sent a questionnaire. Of the 115 questionnaires posted, 70 were returned but 3 were ineligible, leaving a total of 67 controls for analysis (23.6% of 284). Due to the low number of controls, only limited matching with cases was possible and it was not possible to carry out a matched statistical analysis as originally planned. Unmatched analysis was performed using logistic regression with adjustment for age and sex. In the single variable analysis a number of vehicle-related exposures were associated with illness (P less than 0.1). The highest Odds Ratios were seen for lack of screenwash added to windscreen washer fluid (OR=22.06, P less than 0.001), 2 hours or more daily in vehicle with open window (OR=19.83, P less than 0.001) and more than 8 hours daily in a vehicle for job (OR=15.00, P=0.015). The OR for smoking was 11.86 (P less than 0.001). In the multivariate analysis after adjustment for age, sex, season and smoking, the only significant associations observed were for driving through an industrial area (OR=7.17, 95%CI 1.52-33.73, P=0.007) and not using screenwash in windscreen wiper fluid (OR=47.24, 95%CI 3.70-603.63, P less than 0.001). In discussing these results the authors note that growth of Legionella in windscreen fluid reservoirs is biologically plausible, and that commercially marketed screenwashes contain biocidal agents such as propranolol which inhibit growth. Spraying the windscreen of a vehicle creates aerosols which may be sucked into the passenger compartment via the ventilation system or through open windows. A small pilot study of water samples from windscreen wiper reservoirs showed Legionella bacteria in 1 of 5 cars where screenwash was not used, and none of 16 cars where screenwash was used. Assuming the strong association observed in the case-control study indicates a true causative relationship, the researchers estimated that about 21.8% of community acquired sporadic cases of Legionnaires’ disease in those aged under 70 years could be attributable to windscreen wiper fluid without added screenwash. (1) See articles in Health Stream Issues 50 and 56. (2) Windscreen wiper fluid without added screenwash in motor vehicles: a newly identified risk factor for Legionnaires’ disease. Wallensten A et al. European Journal of Epidemiology (2010) 25:661-665.



Water Treatment for Influenza Viruses Recently published research has shown that conventional water treatment and disinfection are sufficient for the effective removal and/or inactivation of influenza viruses from drinking water (1). This confirms previous risk assessments based on knowledge of viral structural properties, and provides reassurance to the water industry that transmission risks through adequately treated drinking water supplies are low even if source waters are subject to sewage contamination from infected communities. Two influenza virus strains were used in the experiments: • an isolate of highly pathogenic avian influenza H5N1 from Cambodia. Influenza viruses in the H5N1 group are transmitted readily between susceptible bird species but rarely to humans. Only 505 human cases of H5N1 infection have been confirmed worldwide since 2003; however these have been associated with a very high fatality rate (60%). The evidence indicates that subsequent transmission from person to person is extremely rare, but it is feared that mutation or recombination of the virus could generate a readily transmissible strain and lead to a devastating pandemic. Influenza in birds is predominantly an infection of the gastrointestinal tract and excreted virus may remain infectious in water for long periods depending on ambient conditions. Some human cases of H5N1 were reportedly associated with diarrhoeal disease, leading to speculation that transmission through water supplies might be possible (2).

• an isolate of human seasonal influenza H1N1 originally isolated from a person in Puerto Rico in 1934. The authors note that their research was carried out before the emergence of the recent novel pandemic strain of H1N1 influenza in Mexico in March 2009 (popularly dubbed “Swine Flu”). It is not known whether the susceptibility of these two H1N1 isolates to water treatment and disinfection processes is the same, but at this time there is no reason to suspect any significant differences. Symptoms of diarrhoea and vomiting have been reported to occur in 25% to 50% of people infected with the 2009 pandemic strain, and

recent research has shown that influenza viruses can be shed in human faeces as well as respiratory secretions. It appears therefore that influenza viruses infectious to humans may commonly occur in water sources subject to sewage contamination. Although the initial 2009 H1N1 outbreak in Mexico appeared to have a relatively high death rate, this was not observed in other countries as the pandemic spread. Nevertheless the H1N1 (Swine Flu) pandemic caused significant morbidity and mortality in groups of people who are not usually severely affected by seasonal influenza, including children under 2 years of age, pregnant women, and people of all ages with chronic health conditions (3).

The experimental work included an assessment of the effects of physical treatments (coagulation-flocculation-settling, membrane ultrafiltration and UV) on the H5N1 virus and tests of chemical disinfectants (monochloramine, chloride dioxide, chlorine and ozone) on both viruses. The infectivity of the influenza viruses was assessed using tissue culture to detect cytopathic effects. Bacteriophage MS2 was included in some experiments for comparison. This bacteriophage has similar structural characteristics to human enteroviruses and Hepatitis A virus. Raw river water was used for the coagulation tests, surface water treated by clarification and ozonation was used for the remaining experiments.

Jar test experiments were done to examine the effect of three coagulants (aluminium sulphate Al2(SO4)3, ferric chloride FeCl3 and aluminium poly-chlorosulfate WAC-HB) on two different river waters at pH 7.8 and ambient temperature (22 degrees C +/- 2 degrees C). The results indicated that simply mixing with river water caused a 1 to 2-log decrease in viral titre and this appeared to be due to viral inactivation not aggregation or binding to particulates. The effect of coagulation-flocculation-settling varied between 0 and 1.5-log removal, with a greater effect seen in the more turbid water (15 FNU versus 6 FNU).

The effect of membrane ultrafiltration was tested at bench scale using filtration units each comprising 6 internal-filtration hollow fibres of polyethersulfone



(filtration surface area 50 cm2 per unit) with a molecular weight cut-off of 150 kDaltons. Virus challenge tests were performed in triplicate after membrane preparation to obtain a stable permeability value and integrity tests of each filter module. Filtration was carried out at a pressure of 0.3 to 0.4 bar for variable times with input water turbidity of 0.25 FNU. Filtrate samples were assayed near the beginning (10 min), middle (20 min) and end (30 min) of filtration time, resulting in nine samples for the H5N1 challenge. Eight of the nine samples showed no detectable virus after filtration, corresponding to a removal of 4.4-logs or greater. The remaining sample (from 30 min filtration time) showed 3.3-log removal of virus. Parallel experiments with MS2 showed that removal of this smaller (24 nm diameter) non-enveloped virus was slightly less efficient than removal of the enveloped H5N1 virus (80-100 nm diameter).

Ozonation experiments were conducted using target residual concentrations of 0.5 mg/L and 1 mg/L after 10 minutes contact time. The actual residual ozone levels achieved were 0.4 and 1.2 mg/L for H5N1, and 0.5 and 1.1 mg/L for H1N1 after 10 minutes. The results demonstrated at least a 4-log reduction in influenza virus infectivity for all tested ozone doses. UV experiments were done using a mercury low vapour pressure lamp with peak emission at 253.7 nm and typical water treatment doses (25, 40 and 60 mJ/cm2). More than 5.5-logs of virus inactivation were observed for influenza H5N1 at all UV doses. UV inactivation of MS2 was less effective, with observed reductions of 1.87, 2.88 and 3.65-logs respectively at the three tested UV doses.

Experiments using chlorine-based disinfectants were conducted using contact times of 5, 15, 30, 60 and 120 minutes with doses selected to achieve typical drinking water treatment residuals. For H5N1 a Ct of 60 mg/L.min for chloramine produced greater that 4-log removal. Limited experiments with H1N1 suggested this isolate was more sensitive to chloramine than H5N1. Chlorine dioxide was highly effective against H5N1, showing more than 4-logs inactivation with a residual of 0.3 mg/L after 5 minutes. Similar results were observed for H1N1. Initial experiments with chlorine indicated greater than 4-log reduction of H5N1 after a contact time of

5 minutes and residual target of 0.3 mg/L, however the high chlorine demand of the virus inoculum prevented achievement of stable residuals. The virus was then concentrated by centrifugation to allow subsequent dilution into test samples to reduce the chlorine demand. These experiments showed more than 2.8-log inactivation with 0.3 mg/L residual chlorine after 5 minutes contact time (higher inactivation may have occurred but could not be shown due to the number of virus in the inoculum and the detection limit of the test method).

The authors concluded that although coagulation-flocculation-settling did not significantly reduce concentrations of influenza viruses, the other water treatment and disinfection processes tested here were found to be effective under currently accepted operating parameters. Where comparisons were done, the inactivation of influenza viruses was similar to or more efficient than inactivation of the MS2 virus, suggesting that treatment processes designed to inactivate recognised waterborne viruses are likely to also be effective against influenza viruses. These findings also enable the definition of enhanced treatment parameters that could be implemented in future pandemic situations if significant contamination of water supplies by influenza viruses is suspected.

1) Assessment of the removal and inactivation of influenza viruses H5N1 and H1N1 by drinking water treatment. Lenes D et al. Water Research (2010) 44: 2473-2486. 2) See Health Stream Issue 40 for a report on avian influenza H5N1. 3) Comparing deaths from pandemic and seasonal influenza. Pandemic (H1N1) 2009 briefing note 20. http://www.who.int/csr/disease/swineflu/notes/briefing_20091222/en/ News Items US Drinking Water Outbreaks 1971- 2006 A review of US disease outbreaks related to drinking water has identified several clear trends in outbreak occurrence over the 36-year interval examined. Trends identified by the analysis included: • The annual number of reported drinking water outbreaks fell significantly over time, especially after 1980. • The proportion of outbreaks attributed to public water systems declined while conversely the



proportion attributed to individual water systems increased. • There was a decline in the proportion and number of outbreaks from untreated or improperly treated public surface waters, mostly after the promulgation of the Surface Water Treatment Rule in 1989. • The proportion of outbreaks attributed to untreated or improperly treated groundwater supplies did not change over time. However, implementation of the Groundwater Rule (beginning in late 2009) is expected to significantly improve the safety of public groundwater systems in the US. • Legionellosis outbreaks became reportable to the WBDOSS only in 2001 but accounted for 29% of drinking water associated outbreaks in the following 5 years. • While the proportion of outbreaks attributable to distribution systems deficiencies remained constant, outbreaks associated with premises plumbing increased (even excluding Legionella). • Non-community outbreaks tended to occur in campgrounds, cabins and other recreational areas as well as restaurants and educational institutions. Most community outbreaks involved residential settings, and health care institutions were the second most common setting for such outbreaks. • While data collection and data quality systems have improved over time there are still some areas of concern. The mean number of reported cases per outbreak has not changes over time; suggesting perhaps that the ability to detect small outbreaks has not improved. The proportion of outbreaks where no deficiency in the water supply system was identified has increased while the mean strength of evidence linking outbreaks to drinking water (judged on a four-level scale on the combined epidemiological, environmental and clinical information available for each outbreak) has declined. There was a trend for less environmental evidence to be available in the last two decades, possibly suggesting less extensive investigation of outbreaks. This may be due to constraints on resources at state level. The review made a number of recommendations to prevent waterborne disease and improve surveillance in the US. Causes of Outbreaks Associated with Drinking Water in the United States from 1971 to 2006. Craun et al. (2010) Clinical Microbiology Reviews 23(3): 507–528.

Victorian State Guidelines The Department of Health in Victoria, Australia recently released two set of water-related Guidelines. 1) Victorian framework for water treatment operator competencies - Best practice guidelines. These Guidelines provide a minimum competency framework for those directly involved in water treatment activities. They are a joint initiative of the Department of Health and the Victorian Water Industry Association. These Guidelines can be downloaded from: http://www.health.vic.gov.au/environment/water/ drinking.htm 2) Draft guidelines for validating treatment processes for pathogen reduction: supporting Class A water recycling schemes in Victoria. This draft document has been released for public comment until 1 November 2010. Class A recycled water schemes are those with a high potential for direct human contact with recycled water. These Guidelines can be downloaded from: http://www.health.vic.gov.au/environment/ water/pathogen-reduction.htm Update on Rabbit Cryptosporidium Outbreak Retrospective analysis of syndromic surveillance data has suggested that the waterborne cryptosporidiosis outbreak that occurred in the East Midlands region of England in June/July 2008 was associated with about 422 excess diarrhoea cases in the community. Previous investigation of this outbreak, which was attributed to faecal contamination from a single rabbit, had identified only 33 clinical cases of which 23 were confirmed by genotyping of the pathogen from faecal samples (See Health Stream Issue 51). The new analysis used data from a National Health Service telephone helpline and surveillance information automatically extracted from the clinical records of over 3500 General Practices. The GP data indicated a rise in consultation rates for diarrhoea and gastroenteritis in the affected area began before any publicity about the outbreak had occurred, however calls to the telephone hotline increased only after the public became aware of it. Value of syndromic surveillance in monitoring a focal waterborne outbreak due to an unusual Cryptosporidium genotype in Northamptonshire, United Kingdom, June – July 2008 Smith S et al. Euro Surveillance. 2010;15(33): pii=19643



From the Literature

Web-bonus articles Summaries of these additional articles are available in the web page version of Health Stream and are included in the searchable archive at: www.wqra.com.au/WQRA_publications.htm Respiratory effect related to exposure of different concentrations of arsenic in drinking water in West Bengal, India. Chattopadhyay BP, Mukherjee AK, Gangopadhyay PK, et al. (2010) Journal of Environmental Science and Engineering, 52(2); 147-154. Health risk assessment of inorganic arsenic intake of Cambodia residents through groundwater drinking pathway. Phan K, Sthiannopkao S, Kim KW, et al. (2010) Water Research, doi:10.1016/j.watres.2010.06.021 Simultaneous determination and assessment of 4-nonylphenol, bisphenol A and triclosan in tap water, bottled water and baby bottles. Li X, Ying GG, Su HC, et al. (2010) Environment International, 36(6); 557-562. Genotoxicity of water concentrates from recreational pools after various disinfection methods. Liviac D, Wagner ED, Mitch WA, et al. (2010) Environmental Science and Technology, 44(9); 3527-3532. Effect of production variables on microbiological removal in locally-produced ceramic filters for household water treatment. Lantagne D, Klarman M, Mayer A, et al. (2010) International Journal of Environmental Health Research, 20(3); 171-187. Failing our children: lead in U.S. school drinking water. Lambrinidou Y, Triantafyllidou S and Edwards M. (2010) New solutions: a journal of environmental and occupational health policy : NS, 20(1); 25-47. Feasibility and impact of placing water coolers on sales of sugar-sweetened beverages in Dutch secondary school canteens. Visscher TLS, Van Hal WCW, Blokdijk L, et al.. (2010) Obesity Facts, 3(2); 109-115. Microbial contamination and associated health burden of rainwater harvesting in Bangladesh. Karim MR. (2010) Water Science and Technology: a Journal of the International Association on Water Pollution Research, 61(8); 2129-2135. Distribution of uranium in German bottled and tap water. Birke M, Rauch U, Lorenz H and Kringel R. (2010) Journal of Geochemical Exploration, doi:10.1016/j.gexplo.2010.04.003 The quality of drinking water stored in canteens of field soldiers as a potential source of enteric diseases. Gavrieli B, Potasman I and Armon RH. (2010) Journal of Water and Health, 8(2); 236-246. Using multi-criteria decision analysis to assess the vulnerability of drinking water utilities. Joerin F, Cool G, Rodriguez MJ, et al.. (2010) Environmental Monitoring and Assessment, 166(1-4); 313-330.

Arsenic

Arsenic exposure from drinking water, and all-cause and chronic-disease mortalities in Bangladesh (HEALS): a prospective cohort study. Argos M, Kalra T, Rathouz PJ et al. (2010) The lancet 376 (9737) 252-25. There are an estimated 35-77 million people in Bangladesh that have been chronically exposed to increased concentrations of arsenic through drinking water. Dose-dependent associations have been found between arsenic levels in well water and cancers of the bladder, kidney, skin and lung as well as peripheral vascular disease. Increased mortality rates from chronic diseases in arsenic-exposed populations have been reported in studies conducted in the USA, Chile, Argentina, Taiwan and Bangladesh. These studies did not use individual-level data however and were retrospective in design. The prospective cohort Health Effects of Arsenic Longitudinal Study (HEALS) provided a valuable opportunity to investigate the association between arsenic exposure and mortality rates using individual-level data. This paper uses data from the HEALS cohort to assess the risk of all-cause and chronic mortality relative to arsenic exposure as measured by well water concentrations and arsenic concentrations in urine. The effect of changes in 2-4 year arsenic exposure on risk of all-cause mortality was also assessed. The HEALS study was conducted in Araihazar, Bangladesh. Between October 2000 and May 2002, married individuals aged 18-75 years who had resided in the study area for at least 5 years were sampled. Trained study physicians conducted interviews and clinical assessments and collected urine and blood samples from participants in their homes using structured protocols. Follow-up of the cohort was conducted from September 2002 to May 2004 (follow-up 1), June 2004 to August 2006 (follow-up 2) and January 2007 to February 2009 (follow-up 3). Assessment of mortality was conducted from 2000 to 2009 at every follow-up interview visit at home. A verbal autopsy questionnaire was used to investigate and assign the cause of death in study participants. All of the 5966 wells in the study area were tested for the presence of



arsenic in the water. The arsenic dose was calculated using the arsenic concentration in water of the primary well multiplied by the self-reported daily amount of water consumed. Total arsenic concentration in urine was also measured as well as creatinine in urine and creatinine-adjusted total arsenic concentration in urine. The maximum concentration in well water was 864 microgram/L. There were 11,746 men and women enrolled in the HEALS cohort. Among the cohort there were 407 deaths between October 2000 and February 2009. Spot urine samples were provided by 11,224 of the 11,746 participants interviewed at baseline, 11,109 of 11,323 interviewed at follow-up 1, and 10,726 of 10,934 interviewed at follow-up 2. Arsenic exposure (baseline concentration of arsenic in well water, arsenic dose per day and total arsenic concentration in urine) was associated with all-cause mortality. Similar results were seen for arsenic dose per day and total arsenic concentration in urine. A one-quartile increase in arsenic concentration in well water was associated with a 15% increase in all-cause mortality (95% CI 1.05-1.26), with corresponding increases of 14% (1.04-1.25) for arsenic dose per day and 13% (1.03-1.24) for total arsenic concentration in urine. Similar results were found for arsenic exposure and mortality associated with chronic disease. After adjustment for potential confounders, the estimated summary attributable proportion based on the arsenic concentration in well water for all-cause and chronic disease mortalities were 21% and 24%, respectively. Two-year and 4-year changes in arsenic exposure (measured as repeated total arsenic concentrations in urine) after enrolment of the baseline cohort were assessed. The multivariate-adjusted hazard ratio (HR) for the high baseline exposure compared to the low baseline exposure was 1.46 (85% CI 1.14-1.86) for deaths occurring after follow-up 1. Similar increased risks of mortality were found when individuals with low exposure at baseline and follow-up 1 were compared with those with high exposure at baseline and low exposure at follow-up 1 or high exposure at baseline and follow-up 1. The multivariable adjusted HR when comparing high exposure at baseline with low exposure at baseline was 1.34 (0.98-1.84) for deaths occurring after follow-up 2.

The risk of all-cause mortality and chronic-disease mortality was found to increase with increasing exposure to arsenic. Long-term exposure to arsenic was a more important predictor of mortality than were subsequent short-term changes of exposure. It was noted that once chronically exposed, decreasing exposure for a short period of time did not reduce an individual’s risk of mortality. Initiatives are in progress to reduce exposure to arsenic in drinking water, however investigation into solutions to mitigate the resulting health effects of arsenic exposure deserve urgent attention and resources. Future research using prospectively collected data examining exposure changes at the individual level will add strength to our understanding of the effect that changes in exposure have on the long-term mortality risk.

Cancer

Using residential history and groundwater modeling to examine drinking water exposure and breast cancer. Gallagher LG, Webster TF, Aschengrau A and Vieira VM. (2010) Environmental Health Perspectives, 118(6); 749-755. Spatial analysis of two population-based case-control studies of breast cancer has suggested a possible link between breast cancer and groundwater plumes contaminated by landfills and wastewater in upper Cape Cod, Massachusetts. On the basis of the locations of public and private wells, it was determined that the Barnstable Water Pollution Control Facility (BWPCF) was the only source of wastewater effluent with the potential to impact the drinking water of this study population. Three public drinking water wells operated by the Barnstable Water Company (BWC) and several private wells are located within the suspected plume boundary. The objective of this study was to use an extensive exposure model to test the hypothesis that drinking water contaminated by municipal wastewater effluent from the BWPCF may be associated with breast cancer. This study used residential histories from 1943 to 1993, questionnaire data on self-reported sources of drinking water (public or private) and on the use of bottled water, operating information for the



BWC and the BWPCF, and a modified three-dimensional groundwater model from the U.S. Geological Survey (USGS) to estimate when exposure occurred and which participants were exposed. Varying latency periods and exposure durations were examined. Data on breast cancer cases and controls were obtained from two population-based case-control studies which together had a total of 638 women who had been diagnosed with breast cancer and 842 controls, all of whom had been permanent residents of five towns in upper Cape Cod. The Massachusetts Cancer Registry was used to identify incident breast cancer cases diagnosed between 1983 and 1993. Cases and controls were comparable in age and vital status. Study participants were interviewed and information was collected on demographic characteristics and breast cancer risk factors, sources of drinking water (public or private), and residential histories over a 40-year period. All residential addresses in upper Cape Cod were geocoded using GIS. The first aim of the exposure assessment was to determine when the drinking water wells were impacted by effluent from the BWPCF. A three-dimensional finite-difference groundwater model (MODFLOW) was modified from the USGS that accounted for both horizontal movement of the plume, as well as plume depth in relation to locations of drinking water wells. Questionnaire data were used to determine the drinking water source (public or private) of the participants for each of their residences. Participants were asked if they regularly used bottled water and therefore bottled water use was examined by stratifying the analysis on whether women ever regularly used bottled water. Residential histories were then used to identify which participants were living at residences during years when drinking water was impacted by effluent. Groundwater modelling showed that effluent from the BWPCF reached drinking water wells for the public water supplier BWC as early as 1966. It was estimated that effluent would have arrived at different times depending on the pumping rate. If the pumping rate was low then exposure would have begun in 1971 and if the pumping rate was high, exposure would have begun in 1966. Associations

with breast cancer were estimated for greater than 0 to 5 years, greater than 5 years and greater than 10 years of exposure relative to no exposure at any time during the study period. When latency was not considered, there were small increases in breast cancer Odds Ratios for participants exposed greater than 10 years compared with those who were never exposed [adjusted odds ratio (AOR) = 1.3; 95% CI, 0.9-2.0 for low pumping rate and AOR = 1.3; 95% CI, 0.9-1.9 for high pumping rate]. When a 10-year latency period was considered, AORs for subjects exposed greater than 5 years were 1.5 (95% CI, 0.9-2.7) and AOR = 1.4 (95% CI 0.9-2.2) for low and high pumping rates, respectively. For exposure greater than 10 years, the AOR was 1.6 (95% CI, 0.8-3.2) for the high pumping rate however, AORs could not be calculated for the low pumping rate because of small numbers. Statistically significant associations were found for ever-exposed versus never exposed women when a 20-year latency period was assumed (AOR = 1.9; 95% CI, 1.0-3.4). Across all latency periods and pumping rates, a statistically significant association was found for ever-exposed versus never-exposed women who did not regularly use bottled water and nonstatistically significant inverse associations were found among women who did regularly use bottled water. The strongest association was found for women who did not use bottled water when 20 years latency and a high pumping rate were assumed (AOR = 2.5; 95% CI, 1.2-5.3 and AOR = 1.0; 95% CI, 0.3-3.3 for nonbottled water users and bottled water users, respectively). This study found increased breast cancer for subjects ever exposed to contaminated drinking water wells when considering various latency periods, but little to no evidence was found of an association when latency was ignored. Associations were found to be strongest among women who were not regular bottled water users and among women exposed for long durations when latency was accounted for. The BWPCF was and continues to be a major source of groundwater recharge in upper Cape Cod. Area groundwater sources for drinking water are now subject to more protections and the impact of sewage on groundwater has been carefully considered in recent expansion plans for the facility. However, this study suggests that the sewage plume emanating



from the facility may have had a significant historical impact on drinking water and health outcomes.

Cyanobacteria

Predicting the vulnerability of reservoirs to poor water quality and cyanobacterial blooms. Leigh C, Burford MA, Roberts DT and Udy JW. (2010) Water Research, 44(15): 4487-4496. There is growing concern over the increased reporting of toxic cyanobacterial blooms in drinking water reservoirs worldwide, particularly in the summer months. Global warming, changes in rainfall patterns and increasing eutrophication are predicted to increase nutrient loads and algal growth in tropical and temperate systems. Cyanobacterial blooms in drinking water reservoirs present a major ecosystem functioning issue and a risk to human health. The ability to predict whether reservoirs may be more or less vulnerable to poor water quality and toxic cyanobacterial blooms, and why, is important for reliable hazard prevention, planning and management. This study developed an index of vulnerability to poor water quality based on simple measure of reservoir and catchment characteristics, rather than water quality data. The index’s ability to predict this vulnerability was tested using water quality and cyanobacterial data collected from 15 drinking water reservoirs in subtropical Queensland. The vulnerability index used parameters which satisfied the following four conditions: (1) correlation with water quality was well established in the literature; (2) parameters were easily calculated from readily available data on reservoir or catchment characteristics; (3) parameters were not strongly correlated with each other, and (4) parameters were relatively static or predictable though time so that the index was unaffected by substantial spatial and temporal variation. The vulnerability index (VI) was calculated from a formula based on the following five parameters: percentage grazing land cover, reservoir shoreline to surface area ratio, reservoir volume at full supply capacity, reservoir volume to catchment area ratio and age since dam construction. Application of log transformation and range standardisation to the parameters was used to give

each an equivalent weighting in the formula, and a comparative index of vulnerability was created among the 15 reservoirs. The possible values of VI ranged from 0 (lowest vulnerability) to 1 (highest vulnerability). The ability of the index to predict the vulnerability of reservoirs to poor water quality and algal blooms was tested by assessing the correlation between index scores and water quality parameters in the 15 reservoirs. Each reservoir was sampled once between 9 February and 3 March 2009 in the late summer period. At least three sites were sampled in each reservoir including” near the dam wall, mid-reservoir, and in the upstream section of each reservoir. At each site, a 3 m depth-integrated sample of surface water was collected as well as bottom water from 1m above the bottom. Surface water was analysed for total nitrogen and phosphorus, dissolved inorganic nitrogen and phosphorus, and chlorophyll a concentrations as well as algal identification and cell densities, including potentially toxic cyanobacterial species. Bottom water samples were analysed for the same parameters, excluding chlorophyll a and algal identification. Data from a previous study on 7 of the 15 reservoirs were also used to assess the effectiveness of the Vulnerability Index. In this study, water quality was assessed at the dam wall and upstream in each reservoir during spring (October 2004), early summer (December 2004), late summer (February 2005) and autumn (April 2005). A number of positive statistically significant correlations were observed between water quality parameters and VI scores. These correlations were found to be stronger and more often statistically significant than the correlations between water quality parameters and each of the five individual parameters used in the VI calculations. Significant correlations were found between the VI and both the densities and proportions of algal cells in all study periods, except October 2004 which had non-significant correlations. The strongest of the significant correlations were with total algal and cyanobacterial cell densities and the strongest of these were found in February 2009 (R=0.82 and 0.84) and December 2004 (R=0.86 and 0.86).



The VI was applied to a new dam being constructed (Wyaralong) in Queensland to compare its potential vulnerability with the 15 reservoirs already examined. On the basis of the planned dimensions and current grazing cover it was predicted that the new dam would have mid-range vulnerability (0.55), for at least 5 years after completion. However, 100 years after completion, the VI would be at the higher end of vulnerability to eutrophication and cyanobacterial blooms and would be the fourth most vulnerable reservoir. By decreasing or increasing the percentage of grazing land cover in Wyaralong’s catchment by 10% via reforestation, the predicted VI will either reach the same endpoint after only 5 years (10% more grazing cover) or remain below this point for at least 100 years (10% less grazing cover) assuming all other parameters except the age of the reservoir were unchanged. This analysis suggests that strong links exist between the physical environmental of dammed river systems, their physicochemical characteristics and algal ecology. This study showed that the VI was an effective indicator of the potential for summer blooms of cyanobacterial in subtropical reservoirs. The VI could provide input to the planning of new reservoirs and assist in decision making about investment to mitigate adverse water quality outcomes. It is recommended that similar studies in other reservoirs within subtropical, tropical and even temperate climates be conducted to confirm the generic usefulness of the VI as adaptations may be required to achieve an acceptable level of correlation between the VI and water quality parameters for any one set of reservoirs.

Extreme Events

The 2007 storm impacts on Melbourne's unfiltered water supply. Hellier K and Stevens M. (2010) Water (J Australian Water Association), 37(1); 149-152. Melbourne Australia is one of the few large cities in the world to use unfiltered drinking water. This water is drawn from two large protected forest catchments; the Upper Yarra and the Thompson. The Upper Yarra Reservoir is located to the east of Melbourne, and

water from this reservoir supplies several small towns in the upper Yarra Valley as well as supplying Silvan Reservoir, which transfers water to most parts of Melbourne. The Thompson catchment and Thompson Reservoir are further to the east and water from this reservoir is transferred via a tunnel to the Yarra River and hence to the Upper Yarra Reservoir. Water from these pristine catchments is not filtered but is disinfected before reticulation. A major storm event occurred in the two catchments on 27 June 2007 with rainfall ranging from 43 mm to 231 mm over a period of 18 to 24 hours. Prior to this storm event the catchments had experienced record drought conditions. The resulting combined streamflow of 30 gigaL over the next two days into the Thomson and Upper Yarra reservoirs was the highest on record. These streamflows were very turbid because of the drought impacts on the catchment. Two days after the onset of the storm, the turbidity of streamflows in the Yarra River and water transferred from the Thompson River were in the range of 50 to 100 NTU. The flow to the Upper Yarra Reservoir from the weir on the Thomson River was shut off on the 30th of June and the turbidity load and inflow momentum on the Upper Yarra reservoir was reduced. During the week after the storm, the turbidity near the outlet of the Upper Yarra reservoir varied from 7 NTU at the surface to 40 NTU near the bottom. Despite the use of a near-surface offtake point the turbidity of the water supplied from the outlet rose gradually to between 10 and 15 NTU. The transfer of water from the Upper Yarra Reservoir to Silvan Reservoir which supplies a large portion of Melbourne’s water, was minimised and water supplied from alternative sources including the O’Shannassy catchment was increased. During the second week of July complete mixing occurred within the Upper Yarra Reservoir and as a result on the 14th of July the turbidity rose to about 24 NTU throughout the water column and stayed above 20 NTU for about 10 days. Yarra Valley Water in consultation with the Department of Human Services and Melbourne Water initiated boil water notices on 16th of July for over 6000 customers in the Upper Yarra Valley townships because turbidity entering these areas was considered high enough to potentially compromise the effectiveness of the existing



disinfection plants. These five townships received unfiltered water with a variety of disinfection treatments; UV-only (low pressure), UV (medium pressure) and chlorination, and chlorination-only disinfection. Water quality monitoring was increased during the incident to verify the effectiveness of disinfection against potential bacterial pathogens. Disinfection validation information specific to the Upper Yarra system was obtained and from this information Melbourne Water established a specific pubic health limit of 15 NTU for turbidity for its unfiltered, protected catchment sources, this being the point at which the UV dose for medium pressure UV plants was reduced near to critical limits. Chlorination tests indicated that water of 20 NTU could still be effectively disinfected for bacterial contaminants by chlorine alone. The boil water notices were lifted on the 14th of August after the turbidity had dropped below 10 NTU, by mid November the turbidity was close to normal (3 NTU). The concentration of bacterial indicators measured in the Upper Yarra Reservoir was low after the storm event (less than 10 E.coli/100ml) despite the high turbidity. No microbiological exceedances occurred during the incident either at customer taps or at Melbourne Water’s entry points (after disinfection) to the water supply zones. As the intensity of this storm event exceeded any studied during previous pathogen risk assessment studies, a sampling program was implemented to assess the presence of Cryptosporidium and Giardia. The prevalence of Cryptosporidium in water samples downstream of Upper Yarra Reservoir was 28% positive at concentrations between 0.15 and 0.95 oocysts/L when assessed by microscopy. This was higher than normal (5% to 10% of samples positive) based on routine monthly water monitoring. During and after the incident, 79 x20L samples were collected for more detailed genetic analysis of Cryptosporidium. One of the samples contained the C. parvum genotype 2 Type A although it was at a low concentration that could not be quantified. Previous research in the catchments had indicated that human-infectious genotypes of Cryptosporidium were rare. A quantitative microbial risk assessment (QMRA) was conducted for human-infectious Crypto-

sporidium. The risk assessment predicted that an outbreak would not occur in Melbourne for the concentration of genotypes of oocysts thought to be present. The Cryptosporidium results along with the QMRA analysis were presented to the Victorian Department of Human Services, who determined that the risk of human infectious Cryptosporidium to the consumers of Melbourne’s drinking water was low. As a result of this information, a boil water notice for the greater Melbourne area supplied from Silvan Reservoir was considered to be unnecessary. There was an increase in consumer complaints in some distribution areas close to the Silvan Reservoir due to increased colour as a result of a larger proportion of water being sourced from alternative supplies. The investigation undertaken following the June 2007 Upper Yarra storm event increased knowledge of water quality impacts of extreme events in the protected catchments and reservoirs. Of particular interest was the finding that the Cryptosporidium risk from the protected source water did not increase significantly. During this 2007 incident, event sampling of streamflows into reservoirs to characterise the turbidity and microbial load (bacterial indicators first, followed by pathogens if required) was not conducted. Had this occurred then it would have assisted in the earlier determination of pathogen risks and a more accurate QMRA.

Fluoride

The association between fluoride in drinking water and dental caries in Danish children. Linking data from health registers, environmental registers and administrative registers. Kirkeskov L, Kristiansen E, Boggild H, et al. (2010) Community Dentistry and Oral Epidemiology, 38(3); 206-212. Drinking water fluoridation is recommended by many health authorities for the prevention of caries. Recently, however, a systematic review was conducted that questioned the quality of evidence on which this recommendation is based. Drinking water fluoridation has not been practiced in Denmark but fluoride toothpaste has been available since the mid-1960s and is currently the predominant type sold.



Fluoride in toothpaste has been suggested to be one of the most important causes of the decrease observed in dental caries in Danish children, however a research study found that a large part of the inter-municipal variation in caries in children and adolescents may be explained by variation in drinking water fluoride concentrations. This study aimed to investigate whether an association exists between the drinking water fluoride concentration and the caries experiences among Danish children and adolescents even though fluoridated toothpaste was extensively used. The study used three cohorts of children born in 1979, 1989 and 1999. The children were identified from the Central Population Register (CPR) and their data linked to data in the Database on Oral Health (SCOR) using the CPR number and transformed address from the CPR Register. Only addresses which were supplied by a public water supplies or private water works supplying 3-9 households were included. Data from waterworks that met the inclusion criteria were aggregated at waterworks level and the median fluoride concentration calculated. A digital map was produced using the Jupiter database (Geological Survey of Denmark and Greenland) which featured the fluoride concentration in the water from the nearest waterworks at any given point. Information on fluoride concentration was transferred to all address points which had information on dental caries available. Fluoride exposure was calculated by summing the product of the fluoride concentration at each address and the time the person had lived at the address divided by the years of known exposure. The outcome analysed was Decayed, Missing and Filled Surfaces (DMFS) for 15-year olds and dmfs for 5-year olds for permanent and primary teeth, respectively. Drinking water fluoride concentration varied considerably within the country. Drinking water in the Western part of the country had the lowest values (less than 0.01 mg/l) and drinking water in the South-Eastern part reached values of 0.40 mg/l. Fluoride concentrations greater than 1.00 mg/l were only found in a few locations. Mean dmfs for 5-year olds were low and below 2 for both children born in 1989 and children born in 1999.

The 90% percentile was found to decrease from 6 for children born in 1989 to 4 for children born in 1999, which is approximately a 30% decrease. Mean DMFS for 15-year olds was below 4 for both children born in 1979 and in 1989. The 90% percentile decreased from 10 for children born in 1979 to 7 for children born in 1989 which is approximately a 30% decrease. There was a negative association between dental caries in the primary dentition (dmfs greater than or equal to 2) of 5-year olds with fluoride concentration in drinking water in children born in 1989, after adjustment for family income and gender. A similar association was found for children born in 1999. A negative association was also found between fluoride concentration in the drinking water and caries in the permanent dentition (DMFS greater than or equal to 2 or DMFS greater than or equal to 6) for 15-year olds born in 1979, after adjustment for gender, and for 15-year olds born in 1989, after adjustment for family income and gender. A negative association was found between dental caries and fluoride concentration in drinking water even at low levels of fluoride exposure (0.125-0.249 mg/l) both in the primary and permanent dentition. Children with greater than 1 mg/l exposure had half the odds of caries relative to children with 0-0.1249 mg/l exposure. There was a clear dose-response relationship between fluoride concentration in water and caries in all cohorts. This study confirms the negative association between fluoride concentration in drinking water and childhood caries which has been found in numerous previous studies. This correlation was found even though fluoridated toothpastes are extensively used in Denmark and caries-prevention programs are implemented by the municipal dental services in Denmark. It is possible that despite the common use of fluoridated toothpaste in the population, some sectors of the population may not have sufficiently effective oral hygiene procedures to benefit fully from the effects of fluoridated toothpaste and may therefore benefit from fluoride in drinking water. This study shows that it is possible to link data from the health, the environmental and the administrative registers within a reasonable time and this linkage offers an opportunity to obtain sample sizes large



enough to identify health effects which may not otherwise be identified. Comment

Dietary sources of fluoride including drinking water can exert beneficial effects on formation of tooth enamel even before the tooth erupts from the gum, whereas toothpaste can provide topical protection only after teeth have emerged.

Obesity

A simple dietary intervention in the school setting decreased incidence of overweight in children. Muckelbauer R, Libuda L, Clausen K, et al. (2009) Obesity Facts, 2(5); 282-285. One of the major challenges for medicine and public health today is the prevention of overweight and obesity. In a recent Cochrane Review no particular intervention that prevents obesity in children was clearly identified, however those which seemed more hopeful included environmental modifications in addition to individual behaviour changes. The researchers had previously carried out a large randomised controlled trial among elementary school children in deprived urban neighbourhoods with an intervention that included environmental modifications to increase access to drinking water and enhance the attractiveness of water consumption. A reduced risk for the prevalence of overweight was found after the education intervention and environmental modifications were implemented in the school setting. This paper describes a secondary analysis of data on the incidence and remission of overweight and obesity in the intervention group (IG) and the control group (CG). The study included children attending the second and third grades of elementary schools in socially deprived neighbourhoods of two cities in Germany. Dortmund was the intervention city and Essen the control city. There were 32 schools (IG: N=17, CG: N=15) that finished the follow up period. The intervention lasted one school year from August 2006 to follow-up measurements in June 2007. In the intervention schools, water fountains providing free cooled and optionally carbonated water were installed and each child received an appealing plastic

water bottle. The educational intervention included four 45 minute classroom lessons based on the theory of planned behaviour and the lessons were conducted at the beginning of the study. The CG did not receive any intervention. Body weights and heights were measured at baseline and follow-up. A secondary outcome was the beverage consumption of the participants and two types of data were used. i) repeated assessment of the water flow of the fountains in the intervention schools (7 times with a mean interval of 43 days); ii) change in children’s beverage consumption (mean number of glasses/day in 7 beverage categories) which was self-reported in a 24-h recall picture-based questionnaire administered at baseline and follow-up. There were 1,641 participants in the IG and 1,309 participants in the CG with anthropometrical data at both baseline and follow-up that were included in the analysis. The mean age of participants was 8.3 years and 50.2% were male. The incidence rate of overweight during the intervention was defined as the number of newly diagnosed overweight children at follow-up in relation to the number of non-overweight children at baseline. The incidence rate of overweight during the follow-up period of 250 days was significantly lower in the IG (3.8%) than in the CG (6.0%), p= 0.018. The remission rate of overweight was defined as the number of participants that were no longer overweight at follow-up divided by the number of all overweight (excluding obese) children at baseline. Accordingly, the remission rate of obesity was calculated on the basis of all obese children at baseline. The remission rate of overweight and obesity did not differ between the IG and CG. Cumulated water flow of the fountains in the intervention schools showed a positive linear time trend over the whole intervention period which indicated a constant consumption level (correlation coefficient r = 0.99, p less than 0.001). Mean self-reported water consumption was found to increase from baseline to follow-up by 1.2 glasses/day in the IG (p less than 0.001) whereas mean consumption of soft drinks/juices decreased by 0.2 glasses/day (p=0.019). However in the CG, neither water consumption nor consumption of soft drinks/juices changed significantly from baseline to follow-up with



a difference of 0.0 glasses/day in both beverage categories (p= 0.576 and p=0.670, respectively). This school-based intervention promoting water consumption was effective for decreasing the incidence of overweight but did not affect remission of overweight or obesity (did not change the rate at which already overweight or obese children moved to a lower weight class). Results of the process evaluation of the intervention trial indicate a good compliance of the teachers and a sustainable integration of the intervention in schools. It is of particular importance that this preventive intervention was effective among children from socially deprived neighbourhoods as this population group has an increased risk of overweight and obesity and also low socio-economic status seems to function as a barrier to traditional, behavioural interventions. The results of this study support the suggestion that prevention programs should consider the environmental intervention approach in addition to individual behavioural changes. Comment

Australian data also show higher rates of overweight and obesity, and shorter height, in children of lower socioeconomic status compared to those of middle and high socioeconomic status.

Estimating perchlorate exposure from food and tap water based on US biomonitoring and occurrence data.

Perchlorate

Huber DR, Blount BC, Mage DT, et al. (2010) Journal of Exposure Science and Environmental Epidemiology, doi:10.1038/jes.2010.31 The inorganic anion perchlorate occurs in water as a result of both natural deposits and from various industrial uses, particularly the manufacture of fireworks, flares and explosives. Plants can absorb perchlorate from soil, fertiliser or irrigation water and as a result this substance is present at low levels in many food items. The charge, shape and size of the perchlorate ion are similar to the iodide ion, and perchlorate can bind and therefore compete with iodide at the sodium iodide symporter (NIS); a transmembrane protein that actively transports iodine into the thyroid follicles for incorporation into the

prohormone tetraiodothyronine (thyroxine or T4) and the active form triodothyronine or T3. These thyroid hormones T3 and T4 play an important role in the regulation of metabolic processes in cells throughout the body and are critical in the developing foetus, especially in brain development. For this analysis, two main sources of perchlorate occurrence and exposure information were used to assess the relative contribution of food and drinking water to the daily intakes in the US population. These were urinary biomonitoring data from the National Health and Nutrition Examination Survey (NHAMES) and the EPA Unregulated Contaminant Monitoring Regulation (UCMR) data for public water supply systems. Estimated intakes were then compared to the reference dose of 0.7 micro g/kg body weight/day (considered to be without appreciable risk of deleterious effects over a lifetime of exposure). In this study, urinary perchlorate data from a random subset of NHANES 2001-2002 was merged with EPA UCMR tap water perchlorate data (primarily 2001-2003). To merge the data three “Bins” were created for categorising the NHANES study participants for whom perchlorate exposure data were available. Data were matched only at the county level due to privacy concerns. Bin I comprised subjects residing in counties where a drinking water system reported detectable perchlorate (greater than or equal to 4 micro g/l) at least once at any sample point. Subjects with no information about perchlorate in drinking water (due to lack of sampling in their home county) were assigned to Bin II. Bin III contained subjects presumed to have no exposure to perchlorate from tap water because they resided in counties where all drinking water samples had perchlorate levels below the reporting limit (4 micro g/l or less). People in Bin III were assumed to have perchlorate exposure mainly from food as work related exposures were excluded. Two adjustments made to the classification of individuals. Firstly, all individuals in Bin I and II who reported not consuming tap water in the day before providing the urine sample were added to Bin III. Also, people in Bin I or Bin II who reported using reverse osmosis water treatment device in their homes (an effective treatment for removing perchlorate from drinking water) were moved into Bin III.



As only spot urine samples were available, creatinine adjustment calculation was used as a surrogate for a 24-h urinary excretion values. Creatinine is excreted by the kidneys at an approximately constant daily rate proportional to an individual’s age, sex, weight, height, race and lean body mass. Urinary perchlorate in a spot sample can be expressed as a fraction relative to creatinine: micro g of perchlorate per g of creatinine excreted. By knowing the total constant daily amount of creatinine produced for an individual’s physical characteristics, his/her daily exposure to perchlorate can be estimated. Estimates of daily perchlorate intake using the creatinine adjustment procedure were possible for 2708 of the 2820 NHANES subjects with perchlorate urinary data. The overall mean estimate of perchlorate daily intakes for all subjects taken together was 0.061 micro g/kg/day. Higher mean intakes were found for younger groups than for the older groups. For ages 6-11 the mean intake was 0.148 micro g/kg/day; for ages 12-19, 0.082 micro g/kg/day for ages greater than or equal to 20 years, 0.076 micro g/kg/day. Higher mean values were seen in males than in females. The mean intake value of 0.088 micro g/kg/day for pregnant women in the 15-44 age group was higher than the mean value of 0.068 micro g/kg/day for all non-pregnant women in the 15-44 age group, and this difference was statistically significant. The mean and median perchlorate intake values for Bin I (representing food and drinking water sources) subjects were typically 15-30% higher than the corresponding values for Bin III (food source only) subjects. The Bin II intakes (unknown drinking water conditions) are similar to, although generally less than, those for Bin III. The difference between Bin I (total) and Bin III (food) when analysing the overall mean for the total population is approximately 0.020 micro g/kg/day, which indicates that about 20% of overall exposure was due to water. At the 90th percentile of the distribution, the difference between Bins 1 and III is 0.031, which indicates that water exposure contributes approximately 16% of total exposure in this group, whereas food constituted the other 84% of perchlorate exposure.

For the overall population and for most of the individual groups analysed, drinking water represents approximately 15-25% of the total perchlorate intake at the mean. The exception to this is children aged 6-11 years in which water represents only approximately 2% of total intake. Low intake from water in this age group may be a consequence of high dairy food/milk intake. Comparisons of food and water intake estimates with the reference dose indicated that perchlorate intake from water at the mean typically comprises approximately 2-5% of the RfD value of 0.7 micro g/kg/day and perchlorate intake from food at the mean is generally between 10% and 15% of the RfD. When exposures for pregnant women were examined, it was calculated that an average 66 kg pregnant women consuming a 90th percentile food dose (0.198 micro g/kg/day) could also drink the 90th percentile of community water for pregnant women (0.033l/kg/day) containing 15 micro g/l perchlorate without exceeding the reference dose. This analysis of NHANES and UCMR data suggests that food typically contributes substantially more to perchlorate exposure than does tap water for the US population. The relative amounts will vary depending on the location and the levels of perchlorate in local tap water and food, however levels fall in the range of approximately 4:1, food to water exposure ratio for the overall population and most age/sex groups. The exception to this appears to be for children aged 6-11 years in which drinking water seems to make a much smaller contribution to total intake. The use of output data such as the NHANES urinary data appears to be a viable and valuable tool for estimating the intake dose for chemicals such as perchlorate and can augment more traditional estimates of food-based doses such as the Food and Drug Administration’s (FDA’s) Total Diet Study (TDS).

POU Treatment

Evaluating a composite cartridge for small system drinking water treatment. Muhammad N, Sinha R, Krishnan R, et al. (2010) Journal of Water and Health, 8(2); 212-223.



This study evaluated the performance of a composite cartridge (Harmsco Filtration Products, West Palm Beach, Florida) that consists of physical filtration, adsorption and UV disinfection in removing physical, chemical and biological contaminants from drinking water. It also identified areas for further improvement and critically evaluated the use of the system as a home water security device against accidental or intentional contaminant events. The device consists of an upper chamber that houses a composite cartridge filter and a lower UV sterilisation chamber to inactivate microbial contaminants. The composite cartridge filter is constructed in three layers surrounding a hollow core. The outer filter media is a pleated pre-filter to remove particles and sediment. The second layer is an activated carbon extrusion to adsorb chemicals and to improve taste. The last layer is a submicron, pleated filter media for removing finer particles and microbial contaminants. After passing through the filter layers, water enters the UV chamber via the internal standpipe. The finished water exits the system housing after UV treatment. The system was challenged with different levels of turbidity ranging from 1 Nephelometric Turbidity Unit (NTU) to 10.4 NTU using a mixture of turbid creek water and dechlorinated potable water . Turbidity is traditionally used as an indicator of water quality and a measure of how effective a treatment process is in removing pathogens from source water. Microbial challenge was conducted using Bacillus subtilis (a predominant aerobic spore forming bacterium), Escherichia coli (a faecal bacterium) and MS2 bacteriophage. To evaluate the performance of the system in removing protozoa, Polystyrene Latex (PSL) beads with a mean size of 2.83 micro m were used as a non-biological surrogate for Cryptosporidium parvum. During the turbidity challenges, influent and effluent concentrations of particles within the Cryptosporidium size range of 2 to 5 micro m were measured to provide an indirect, secondary measure of protozoa removal. Monitoring of heterotrophic plate counts (HPC) in the influent and effluent was also conducted during the turbidity challenges to evaluate heterotrophic bacteria removal by the system (with and without UV treatment). The

system was challenged with a number of chemical contaminants including: methyl tertiary butyl ether (MTBE), a fuel additive; super-chlorination, typical of that required to disinfect a water distribution system following a biological contamination event; disinfection byproducts such as trihalomethanes (THMs) and haloacetic acids (HAA) and diazinon, one of the most widely used organophosphorus pesticides for household as well as agricultural pest control. The composite cartridge system demonstrated the potential for removal of turbidity and Cryptosporidium size particles. When influent turbidity levels were between 1 and 3 NTU, effluent turbidity levels varied between 0.38 and 0.62 NTU and the overall removal efficiencies ranged between 64.5 and 85.6%. When particle counts were examined, influent particle counts between 214 and 5,202 per mL produced effluent particles counts between 94 and 220 per mL and the removal efficiencies varied between 53.6 and 96.5% depending on the feed concentrations. When HPC concentrations were between 463 and 12,350/mL, the effluent HPC concentrations varied between 10 and 125/mL with the UV ON and between 225 and 4,885/mL with the UV OFF. HPC removal efficiencies ranged from 95.3 to 99.2% with the UV ON and between 42 and 84.3% without UV light depending on the feed concentrations. The system showed an adequate removal of PSL beads (as surrogate for Cryptosporidium) and E. coli, however did not perform adequately in removing B. subtilise and MS2 bacteriophage. When the total beads count was approximately 109 in the influent stream, the log removal of PSL beads varied between 2.3 and 2.5 which satisfied the standard for Cryptosporidium removal of 2.0 log. The log removal of B. subtilis ranged between 1.6 and 2.0, with an average log removal of 1.75 for an influent cell concentration ranging between 104 and 105 cells per 100mL. The log removal of E. coli varied between 2.97 and 3.66 with an average log removal of 3.35 for an influent cell concentration of approximately 105 cells per 100 mL. The log removal of MS2 bacteriophage ranged between 1.0 and 1.2 with an average log removal of 1.1 for an influent



cell concentration of approximately 105 cells per 100 ML. The system showed excellent removal of chlorine, THM and diazinon and adequate removal of MTBE and HAA5. There was an overall 96.2% removal of chlorine at influent concentrations ranging between 4.00 and 5.70 mg/L, 84% removal of THMs for influent concentrations ranging between 27.7 and 45.5 mg/L, 99.3% removal of diazinon for an influent concentrations of approximately 64 micro g/L, 49% removal of MTBE for influent concentrations of approximately 1.2 mg/L and 46% removal of HAA5 compounds for an influent concentration of 6.53 to 15.6 micro g/L. The composite cartridge tested here is able to improve the quality and safety of water for individual households and small communities. The treatment capability of the system depended on the target contaminants, therefore it is important to identify the target contaminant to achieve the desired removal and to avoid problems associated with desorption/breakthrough of contaminants. Where there is little or no treatment or where the quality of treated water may have deteriorated during distribution, the system can serve as an additional treatment barrier. The results also showed that B. subtilis spores may be a more conservative surrogate for Cryptosporidium than PSL beads.

Rainwater

Rainwater harvesting: Quality assessment and utilization in The Netherlands. Schets FM, Italiaander R, Van Den Berg HHJL and De Roda Husman AM. (2010) Journal of Water and Health, 8(2); 224-235. Rainwater harvesting is common in remote and rural areas where there is limited access to tap water. However rainwater harvesting is now becoming more common in urban areas where tap water is readily available, motivated possibly by environmental concerns or the wish to reduce the costs of water supply. In The Netherlands, drinking water legislation determines that rainwater may only be used as grey water in the household and it is

recommended explicitly for toilet flushing only. The infection risk at exposure to grey water in the household must be below the generally accepted level of less than one infection per 10,000 persons per year, which is outlined for drinking water in the Dutch Water Act. This study was conducted to gain insight into the microbiological quality of rainwater stored in reservoirs in The Netherlands and the effect of environmental conditions and storage container material on the survival of microorganisms in these reservoirs to verify recommendations on safe collection and storage of rainwater. In 2005, a pilot study was conducted of the microbial quality of rainwater collected at four different sites in The Netherlands. The rainwater collected was used for toilet flushing, cleaning floors and watering plants. Water samples were taken of reservoirs weekly in June 2005 and tested for the presence of total coliforms, E. coli, intestinal enterococci, Campylobacter, Salmonella, Vibrio, Legionella, Aeromonas, Clostridium perfringens and heterotrophic plate count at 22 degrees C. A follow-up study was conducted in 2006 looking specifically at the effects of environmental conditions on the microbiological quality of rainwater in stored reservoirs. Samples were collected from May until August 2006 biweekly from three reservoirs. Samples were tested for the same parameters as the pilot study and also Cryptosporidium and Giardia and enteroviruses. Water temperature was measured for all samples on site and pH and turbidity were recorded in the laboratory. Rainfall data and information on other weather conditions was also obtained. In 2007, laboratory experiments were conducted to study the effect of storage temperature and storage container material on the survival of naturally occurring and seeded E. coli and Aeromonas in rainwater collected from two reservoirs. Water samples were taken from reservoirs and upon sampling, temperature, pH, turbidity and conductivity were determined. Water was stored in polyethylene, galvanised iron and concrete containers in the dark at 15, 25 and 35 degrees C in standard laboratory incubators. Water was stored in duplicate with one container stored without any additives and the other



was seeded with overnight cultures of A. hydrophilia M800 and E. coli WR1. Sampling of water from both the seeded and non-seeded containers was started immediately after inoculation and then one, two, five days and subsequently weekly after inoculation. The 2005 and 2006 results revealed that all (faecal) indicator bacteria as well as Aeromonas and Clostridium perfringens were found in all rainwater reservoirs and the number of positive samples and bacterial counts varied among reservoirs. The 2005 monitoring found Campylobacter sp. and Legionella pneumophila (serogroup 2-14) detected once in the samples taken on different days from one reservoir. Legionella detection failed in seven samples due to growth of non-Legionella background flora. Salmonella and Vibrio were not found in any samples. In 2006, Campylobacter and Legionella were found in some samples. One sample from a reservoir contained one Cryptosporidium oocyst and one sample from other reservoir contained one Giardia cyst. No Salmonella and Vibrio and enteroviruses were found. In each of the reservoirs in the 2005 and 2006 study there was some variation in pH, turbidity and water temperature. Water temperature varied the most in one reservoir in 2005, with an increase from 19 to 33 degree C. During the 2005 study period the weather was fair and stable and there was no significant rainfall. During the study period in 2006 the weather conditions varied strongly with periods of drought alternated with wet episodes and periods of high intensity precipitation and outside temperature fluctuated as well. High concentrations of E. coli and intestinal enterococci were found in all reservoirs on sampling days that were preceded by days with heavy rainfall during 2006 and Campylobacter –positive samples were only found on these sampling days. There was a moderate to strong correlation between rainfall intensity and counts of all microbiological parameters expect C. perfringens. C. perfringens counts were strongly correlated with rainfall amount and wind speed. Both E. coli and A. hydrophila were found to survive longer in PVC containers than in galvanised iron containers. Survival in clay containers appeared to

mimic survival in PVC, however numbers were limited. The numbers of culturable bacteria gradually declined in all containers, however the decline was more rapid at elevated temperatures. The water type also influenced survival of E. coli and A. hydrophila. When the seeded water from one reservoir was stored in PVC containers at 15 degrees C, E. coli and A. hydrophila could still be detected for up to 68 days after seeding. When seeded water from another reservoir was stored in PVC containers at 15 degrees C, E. coli was detected for up to 34 days whereas A. hydrophila could no longer be detected on day 27. Naturally occurring of E. coli and A. hydrophila were present in water from both reservoirs at low numbers that gradually declined and were undetectable within one to two weeks from the beginning of the experiment. This study showed that roof-collected rainwater stored in four different reservoirs in The Netherlands was faecally contaminated and contained human pathogenic microorganisms. The occurrence of total coliforms indicated the possible presence of biofilms in the reservoirs as these organisms can survive and grow in water systems particularly when biofilms are present. The microbiological quality of the stored rainwater did not comply with the Dutch drinking water legislation and WHO drinking water guidelines and therefore should not be consumed without treatment. Health risks may arise from exposure to pathogens when contaminated droplets are inhaled, ingested or come in contact with the skin. Measures to ensure safe collection of rainwater are required including preventing animals from having direct access to the reservoirs and regular cleaning of collection surfaces such as roofs and roof-gutters to prevent washing in of animal faecal droppings deposited on roofs. Safe storage is important and reservoirs should be cleaned or disinfected on a regular basis to prevent biofilm formation and growth of bacteria such as Aeromonas and Legionella. Care should also be taken to ensure hygienic transportation of water and hygienic tapping of water.

Viruses

Chlorine inactivation of human norovirus, murine norovirus and poliovirus in drinking water.



Kitajima M, Tohya Y, Matsubara K, et al. (2010) Letters in Applied Microbiology, 51(1); 119-121. Human noroviruses (HuNoVs) are important agents in the cause of waterborne gastroenteritis as they are very stable in the environment, extremely infective to humans and have caused a number of drinking water outbreaks. Inactivation of HuNoVs by chlorine disinfection has not been well characterised due to the absence of routine in vitro infectivity assay systems for HuNoVs. This study evaluated the reduction of HuNoVs by chlorine disinfection under typical drinking water treatment conditions using murine norovirus (MNV) and poliovirus type 1 (PV1) as viral surrogates. MNV and PV1 are able to be assayed by plaque formation in cell culture. Purified virus stock solutions were inoculated into 100 ml of treated water prior to chlorination, collected from a drinking water treatment plant in Tokyo, Japan. Bench-scale free chlorine disinfection experiments were performed for two initial free chlorine concentrations, 0.1 and 0.5 mg/L. Infectivity of MNV and PV1 was determined by plaque assays in RAW 264.7 and buffalo green monkey (BGM) cells, respectively. Viral RNA was extracted and quantified by TaqMan-based real-time RT-PCR assays for HuNoV, MNV and PV1.

When the initial free chlorine concentration was 0.1 mg/L, the plaque assay showed that MNV and PV1 were gradually inactivated to obtain 4.04 and 3.84 log10 reduction, respectively, after 120 min contact time to chlorine. However the viral RNA titre assayed by PCR was almost constant regardless of the virus type, indicating that reduction in infectivity did not correlate with loss of PCR signal. When the initial free chlorine concentration was 0.5 mg/L, infectivity of MNV and PV1 was reduced by more than 4.00 log10 within 0.5 and 2 min, respectively on the plaque assay. A reduction in the viral RNA PCR signal also occurred but much more slowly than the reduction in infectivity. These results support other recent research showing that human noroviruses can be effectively inactivated by chlorine. Waterborne outbreaks of this virus have been caused mainly by inadequately treated water or disinfection failure.

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to the original papers for full details of the research.

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WQRA HealthStream - Issue 59