WQRA HealthStream - Issue 58

HEALTH STREAM JUNE 2010 PAGE 1

Issue 58 Public Health Newsletter of Water Quality Research Australia June 2010 In this Issue: Boston Main Break 1 Walkerton Outbreak 10th Anniversary 3 News Items 5 Circulation Report 6 From The Literature 6 Web Bonus Articles Arsenic Disinfection Byproducts Nitrate Outbreaks Pharmaceuticals POU Disinfection Rainwater Sporadic Disease Water Hardness Water Quality Mailing 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.

Boston Main Break A break in major water supply pipeline serving the U.S. city of Boston has resulted in a boil water alert being issued for almost 2 million people. Water supplies to 30 communities were affected when a steel connector joining two sections of pipe failed at around 9.30 am on Saturday 1 May. The 10-foot (3 metre) diameter pipe connects the 7-year old MetroWest Water supply tunnel and the older City Tunnel, and provides the main water supply to Boston and a number of other communities. The leaking water quickly forced its way to the surface, creating a small lake and washing away a section of a nearby road before draining into the Charles River. It was estimated that up to 8 million gallons (30 ML) of water was being lost per hour before the broken pipe section was isolated for repairs. The Massachusetts Water Resources Authority (MWRA) initiated emergency response procedures as soon as the leak was detected by an automated alarm system and visually confirmed by security cameras. The initial assessment resulted in a decision not to immediately close down water flow through the ruptured pipe as this could have created significant operational difficulties including loss of back pressure needed to start a pump station and intrusion of air into the water supply system, as well as loss of supply to downstream communities. Instead, flow through the break site was continued for several hours until arrangements were put in place to redirect water through alternative pipelines. Communities which had access to independent local water supplies were also contacted and asked to decrease withdrawals from the MWRA water supply system wherever possible.

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WATER QUALITY RESEARCH AUSTRALIA


By late Saturday afternoon, MWRA had succeeded in redirecting 90% of the usual MetroWest Water supply tunnel flow through alternative routes to bypass the break. To maintain adequate pressure, it was also necessary to bring on-line an emergency supply from an open reservoir via an old brick aqueduct which had been unused for decades. No water quality testing had been conducted recently on this water source and although it was chlorinated before introduction to the pipe network, there was a potential risk that protozoal pathogens such as Giardia or Cryptosporidium might still be present. In view of this uncertainty, it was considered necessary to issue a boil water notice for the 30 affected communities, including part of the city of Boston. Householders and businesses were advised that tap water could be used for bathing, toilet flushing and fire fighting but boiled or bottled water should be used for drinking, cooking, food preparation and tooth brushing. The State Governor also declared a state of emergency for the area affected by the main break. The broken section of pipe was isolated and shut down approximately 9 hours after the break was detected, and the flooded area was then drained to allow inspection of the pipe. Initial fears that the emergency might last for several weeks if the pipe sections needed to be replaced proved to be unfounded, and it was decided that repair of the break using a steel collar would be possible. Fortunately, a suitable steel collar and heavy construction equipment was immediately available from a nearby major pipeline rehabilitation project being undertaken by MWRA. Working around the clock, MWRA staff and contractors were able to complete the repair by 4 am on Monday 3 May. The repaired section was then filled, pressure tested and disinfected before being brought back on-line at 5.30 am the same day. While the repair work was still being undertaken, MWRA and the Massachusetts Department of Environmental Protection developed a water quality testing program and agreed criteria for ending the boil water notice following restoration of normal water supply. An intensive water testing program comprising approximately 400 samples per sampling

round and two sampling rounds per day was agreed, with samples to be tested for total coliforms, E. coli and free chlorine residual. Two consecutive sampling rounds conducted approximately 8 hours apart with clear results would be considered satisfactory for lifting the boil water notice. The affected communities were contacted early on Sunday morning and asked to conduct water sampling according to this program with the results of the second round of tests being received in the early hours of Tuesday morning. The boil water notice was lifted for all 30 communities by 7 am on Tuesday 4 May, some 59 hours after it had been declared. Homeowners and businesses were provided with advice on flushing water lines and water-using equipment within premises before resuming normal water use. The incident highlighted the risks of lack of redundancy for major water supply lines. This risk had already been recognised by MWRA when the MetroWest Water Supply Tunnel was built and commissioned in 2003 to provide a more reliable alternative to the leaking Hultman Aqueduct. The 70-year old Aqueduct was then taken out of service in order to undertake an extensive rehabilitation program to restore it to serviceable condition and install new interconnections with the MetroWest Tunnel. This will provide complete redundancy for Boston’s main water supply pipeline and allow failures in one pipeline to be easily bypassed by using the other pipeline. However until the project is completed in 2014, the water supply system is heavily reliant on the MetroWest Tunnel. A major failure in the new tunnel only seven years after commissioning was an unexpected event, but nevertheless one that had been included in MWRA’s disaster planning program. This preparation, and a certain amount of good fortune, allowed a rapid response to the incident and restoration of normal water supplies in less than three days. MWRA is now reviewing the Hultman Aqueduct rehabilitation program to determine whether staging of the project can be revised to bring the completion date forward without disrupting supply to consumers or running unacceptable risks associated with



sections being out of service. In addition, pieces of the failed coupling recovered from the Charles River will be subjected to forensic examination in an attempt to pinpoint the cause of the failure. MWRA has also reviewed 28 other construction projects to identify any where pipeline couplings of the same or similar type were used. Eight projects were identified as having couplings of similar although not identical type. These projects will be subjected to risk assessments to evaluate failure risks in the light of findings from the investigation of this incident. Walkerton Outbreak 10th Anniversary The Canadian town of Walkerton recently marked the 10th anniversary of the waterborne disease outbreak that devastated the small community (1). The outbreak in May 2000 occurred when E. coli O157 and Campylobacter jejuni bacteria from cattle manure were washed into a well from which drinking water was supplied to the town. The heavily contaminated water was inadequately chlorinated and improperly monitored, resulting in exposure of consumers to the potentially deadly infections. Recognition of tap water as the source of the outbreak, and issuing of a boil water alert, was delayed due to deliberate concealment of adverse microbiological testing results by water system operators. Nearly half the population in the town of 5,000 people became ill and more than 70 people were hospitalised with severe gastroenteritis and a range of complications associated with the infections. Seven people died as a result of the outbreak. Two water supply operators were charged with public endangerment and other offences but were subsequently found guilty of lesser charges after a plea bargain agreement with prosecutors. The judicial inquiry into the tragedy found that a range of factors contributed to the outbreak including: • lack of knowledge, incompetence, poor work

practices and deliberate falsification of test results by water supply operational staff.

• failures of oversight and inadequate follow up on previous water quality problems by local municipal authorities.

• ineffective inspection and oversight practices by provincial authorities, which were partially attributable to budget reductions.

The structure of drinking water regulation in Canada is similar to that of Australia, with drinking water guidelines set at the national level by the federal government but responsibility for regulation of water quality resting with provincial governments. The Walkerton Inquiry produced two detailed reports, with the first dealing with the sequence of events and the causes of the outbreak, and the second making 121 recommendations to improve drinking water safety in the province of Ontario (2). The recommendations included:

Source Protection – development of a coordinated source protection program for the province with management plans for individual watersheds. The framework for developing such programs should be the responsibility of The Ontario Ministry of the Environment (MOE), in consultation with local stakeholders. The MOE should also have responsibility for approval of the management plans. Individual water protection plans should be required for all large or intensive farms, and for smaller farms in sensitive or high-risk areas. Planning processes for other catchment activities should also take into account their potential impact on water supplies.

Standards and Technology - the process by which Canadian federal and provincial governments set drinking water standards should be made more transparent and accessible to public participation, with adequate scientific support at both levels of government. Design and approval of drinking water treatment systems should be based on characterisation of health-related parameters in the raw water source, regardless of the type of source. Minimum requirements for municipal water suppliers should include continuous inline monitoring of turbidity, disinfectant residual, and pressure at the treatment plant with alarms and automatic shut off mechanisms. Disinfectant residuals should also be monitored continuously or frequently in distribution systems. Specific recommendations were also made for laboratory accreditation, and standardisation of water quality sampling and analysis.



Municipal Water Providers - a quality management approach for water supplies should be developed and implemented, including a mandatory system of accreditation and operational planning. This should emphasise the importance of preventive rather than reactive management to protect public health. To ensure accountability the municipal officers responsible for overseeing the management and operation of the water supply be held to a statutory standard of care. Mandatory certification of water system operators should be required. To ensure adequate resourcing, each municipality should be required to develop a financial plan incorporating full cost recovery and allowance for proper asset management of the water supply system.

Provincial Oversight - the Ontario government should develop a comprehensive source-to-tap drinking water policy, and enact a Safe Drinking Water Act. The MOE should create a Watershed Management Branch responsible for coordinating and overseeing watershed planning, and a Drinking Water Branch responsible for overseeing water treatment and distribution systems. Approvals and certifications for drinking water systems should be streamlined into a single owner's licence covering all required aspects for operating a waterworks.

Special Cases

- the Inquiry recommended that all water systems supplying water to the public be covered by appropriate regulations, including small privately owned systems. While noting the cost burden imposed on small systems by regulatory requirements, the Inquiry recommended that any variances from provincial standards should be granted only on the basis of satisfactory risk assessment, not economic hardship. Those systems currently not covered by regulation should have the choice of complying or declaring their supply non-potable with appropriate signage to inform the public. The Inquiry noted however that supplies on First Nations (native American) reserves fall outside the jurisdiction of the provincial government and are the responsibility of the federal government.

Ten years after the outbreak, all of the recommendations have been or are being implemented in Ontario, and major advances have been made in achieving safe drinking water supplies. However, commentators cited in media articles

marking the 10th anniversary of the Walkerton outbreak have noted that safe drinking water is not yet available to all communities in Ontario. Some Canadian provinces have adopted similar regulatory and water quality management strategies similar to those developed in Ontario; however others have not made any significant changes to their regulatory practices. Across Canada there are still many small communities which struggle to provide the resources and skills needed to properly manage water supplies. One article, published in April this year, noted that there were currently 975 ‘boil water’ advisories and 23 ‘do not consume’ warnings in force across Canada. A total of 116 of these advisories applied to First Nations reserves which are the responsibility of the Federal government but are not covered under the provisions of the Canadian Drinking Water Guidelines. A 7-year follow-up study of Walkerton residents showed that many continued to experience long-term adverse health effects. The Walkerton Health Study, was funded by the Ontario Ministry of Health and Long-term Care, and carried out by a multi-disciplinary team of clinicians and researchers. All residents of Walkerton and surrounding areas were invited to participate in the study, regardless of whether they had drunk tap water or suffered symptoms of illness at the time of the outbreak. The medical conditions to be monitored during the study were determined after an extensive review of the medical literature on the two pathogens involved in the outbreak, and included renal complications, hypertension, arthritis, and heart disease. Screening clinics were established in Walkerton for several months of each year from 2002 to 2008, and people exhibiting symptoms at screening visits were referred to appropriate specialists for follow-up and treatment. A total of 4,561 people attended at least one annual screening visit, with 1,568 attending all seven visits. Participants were representative of the overall age and gender distribution of the population in the Walkerton area. The vast majority (98%) reported drinking tap water at the time of the outbreak but only 65% suffered gastroenteritis symptoms. It was found that among those who had experienced severe gastroenteritis during the outbreak, 36% had



developed Irritable Bowel Syndrome, compared to 28% of those who had moderate gastroenteritis and 10% of those who had not been ill. An association was also seen between the severity of gastroenteritis and the subsequent risk of developing hypertension (36% rate of hypertension in those who had experienced severe gastroenteritis, 32% among those with moderate gastroenteritis and 27% for those without illness). There was also a trend for reduced kidney function (as measured by the estimated glomerular filtration rate) with increasing severity of gastrointestinal symptoms. Increased risks were also seen for reactive arthritis (22% for severe gastroenteritis, 18% for moderate gastroenteritis and 16% for no illness). There was no evidence of an association between gastroenteritis symptoms and the subsequent risk of albuminuria (presence of the blood protein albumin in the urine) or dysglycemia (diabetes mellitus, impaired glucose tolerance or impaired fasting glucose). A sub-study in pregnant women showed a tendency for increased risk of pregnancy-related hypertension in those who had experienced more severe gastroenteritis symptoms in the outbreak but this did not reach statistical significance at the p=0.05 level. One of the most severe complications of E. coli O157 infection is HUS (haemolytic uremic syndrome) and survivors of HUS may have permanent kidney damage, potentially requiring a kidney transplant later in life. Therefore there has been a particular focus on children who suffered HUS during the outbreak. The Year 3 follow-up of children who had HUS showed that 32% had microalbuminuria (trace amounts of albumin in the urine) compared to 5% of children who had not had HUS. However by Year 5 these rates had dropped to 20% and 3% respectively, and the Year 7 follow-up showed no worsening of the condition or any overt kidney disease in the children. These findings were more favourable than had been predicted from previous literature on HUS, but continued monitoring of kidney function is still deemed desirable in HUS survivors. While the Walkerton Health Study has now been completed, the research team intends to continue monitoring the long term health outcomes of Walkerton residents until at least 2030 through data linkages with hospital and health care records.

(1) Articles about the Walkerton outbreak can be found in Health Stream issues 18 - 21, 25, 26, 30 and 37. (2) The reports of the Walkerton Commission of Inquiry can be obtained from the Ontario Ministry of the Attorney General website: http://www.attorneygeneral.jus.gov.on.ca/english/about/ pubs/walkerton/ News Items Victorian Risk Management Plan Audits Water businesses in the Australian state of Victoria recently completed the second round of audits required under the Safe Drinking Water Act (2003). In this round 23 of 25 water suppliers and storage managers were found to have complied with the requirements of the Act and associated Regulations, a significant improvement over the compliance rate of 15 out of 25 in the first series of audits. The two businesses which failed to achieve compliance had findings of minor non-compliance relating mainly to: • failure to record all actions or documentation in

the water business’ risk management plan, • failure to implement record keeping in line with

the frequency requirements in the risk management plan.

A report on the outcomes of the audits can be obtained on request from the Manager Drinking Water Regulation: Email: [email protected] Sewage Treatment Change Removes EDC Effects Scientists speaking at the recent Annual Meeting of the Endocrine Society in San Diego USA have reported that an upgrade from a trickling filter process to an activated sludge process at the Boulder, Colorado wastewater plant has resulted in a dramatic decrease in the feminizing effect of raw effluent on male fish. Dr David Norris of the University of Colorado at Boulder reported that feminizing effects in adult male fathead minnows were seen only after prolonged exposure (28 days) in 100% post-upgrade effluent as compared to 7 days in 50% effluent prior to the upgrade. The sewage plant upgrade was not specifically aimed at improving removal of EDCs (endocrine disrupting chemicals) but was undertaken in response to population growth in the city of Boulder and aging of existing infrastructure.



Circulation Report – Issue 58 June 2010 Circulation for the print version of this issue is 2316 copies, with readers in 67 countries. In addition, 2033 readers are registered for email notification of new issues. Australia Algeria Argentina Austria Bangladesh Belgium Brazil Cameroon Canada Chile Chinese Taipei Cyprus Czech Republic Denmark Egypt Finland France

1733 1 1 3 1 1 2 5 46 7 17 1 1 2 6 2 22

Germany Ghana Greece Hong Kong Hungary India Indonesia Ireland Iran Israel Italy Ivory Coast Japan Jordan Lebanon Lesotho Lithuania

32 1 7 18 1 34 8 1 1 10 3 1 49 2 1 1 1

Luxembourg Malaysia Morocco Myanmar Nepal Netherlands New Caledonia New Zealand Nigeria Norway Oman Pakistan Palestine Papua New Guinea Philippines P.R. China Russia

1 23 5 1 6 12 1 21 13 2 2 1 3 6 5 1 2

Saint Lucia Singapore Slovenia South Africa Spain Sri Lanka Sweden Switzerland Thailand Togo UAE UK USA Yugoslavia Zambia Zimbabwe

1 5 3 6 1 3 1 4 10 1 3 52 96 1 1 1

From the Literature

Web-bonus articles Summaries of these additional articles are available in the web page version of Health Stream at: www.wqra.com.au/WQRA_publications.htm Lung cancer in a U.S. population with low to moderate arsenic exposure. Heck JE, Andrew AS, Onega T, et al. (2009) Environmental Health Perspectives, 117; 1718-1723. Maternal drinking water arsenic exposure and perinatal outcomes in Inner Mongolia, China. Myers SL, Lobdell DT, Liu Z, et al. (2010) Journal of epidemiology and community health, 64; 325-329. Detection of Cryptosporidium species and sources of contamination with Cryptosporidium hominis during a waterborne outbreak in north west Wales. Chalmers RM, Robinson G, Elwin K, et al. (2010) Journal of Water & Health, 8; 311-325. Innovative method for prioritizing emerging disinfection by-products (DBPs) in drinking water on the basis of their potential impact on public health. Hebert A, Forestier D, Lenes D, et al. (2010) Water Research, 44; 2997-3312. Exposure to disinfection by-products, fetal growth, and prematurity: A systematic review and meta-analysis. Grellier J, Bennett J, Patelarou E, et al. (2010) Epidemiology, 21:300-313 Is there still a problem with lead in drinking water in the European Union? Hayes, C.R. and Skubala, N.D. (2009) Journal of Water and Health, 7; 569-580.

Nitrates in municipal drinking water and non-hodgkin lymphoma: An ecological cancer case-control study in Taiwan. Chang CC, Tsai SS, Wu TN, Yang CY. (2010) Journal of Toxicology and Environmental Health - Part A: Current Issues, 73: 330-338. Waterborne disease in Norway: emphasizing outbreaks in groundwater systems. Kvitsand HML, Fiksdal L. (2010) Water Science and Technology, 61; 563-571. Microbiological effectiveness of disinfecting water by boiling in rural Guatemala. Rosa G, Miller L and Clasen T. (2010) American Journal of Tropical Medicine and Hygiene, 82; 473-477. Relative validity of a self-completion 24 h recall questionnaire to assess beverage consumption among schoolchildren aged 7 to 9 years. Muckelbauer R, Libuda L and Kersting M. (2010) Public Health Nutrition, 13; 187-195. Beverages obtained from soda fountain machines in the U.S. contain microorganisms, including coliform bacteria. White AS, Godard RD, Belling C, et al. (2010) International Journal of Food Microbiology, 137; 61-66. Effect modification of the association between trihalomethanes and pancreatic cancer by drinking water hardness: Evidence from an ecological study. Chiu HF, Tsai SS, et al.. (2010) Environmental Research, doi:10.1016/j.envres.2010.03.007. Quality of drinking-water at source and point-of-consumption--drinking cup as a high potential recontamination risk: a field study in Bolivia. Rufener S, Mausezahl D, Mosler HJ, Weingartner R. (2010) Journal of Health, Population, and Nutrition, 28; 34-41. Enteric illness risks before and after water treatment improvements. Frost FJ, Tollestrup K, Roberts M, et al. (2009) Journal of Water and Health, 7; 581-589.

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Arsenic

Kidney cancer mortality: Fifty-year latency patterns related to arsenic exposure. Yuan Y, Marshall G, Ferreccio C, Steinmaus C, Liaw J, Bates M and Smith AH. (2010) Epidemiology, 21(1); 103-108. Arsenic in drinking water has been found to be associated with increased risks of kidney cancer in several countries, although the evidence for causation is currently regarded as insufficient by the International Agency for Research on Cancer. This study investigated kidney cancer mortality in the northern region of Chile before, during and after a period of high arsenic exposure from drinking water. More than half of the population of Region II in Chile resides in the cities of Antofagasta and Mejillones which share the same water source. The arsenic concentration in the drinking water for these cities increased in 1958 from 90 micro g/L to an average of 870 micro g/L when water began to be drawn from highly contaminated rivers. When a water treatment plant was introduced in 1971, Antofagasta’s water arsenic concentration dropped to about 110 micro g/L and further reductions occurred with further improvements in treatment. As a comparison population, Region V of Chile was selected. The major city of this region (Valparaiso) has had water arsenic concentrations close to 1 micro g/L. Information on mortality in men and women aged 30 years and above from 1950 to 2000 was collected for Region II and Region V. Causes of death were coded according to the International Classification of Diseases, Ninth Revision (ICD-9). The National Institute of Statistics provided annual estimates of the population living in Regions II and V stratified by age and sex for the period 1950-2000. The kidney cancer mortality rates increased rapidly from 1950 through 2000 in both regions. Age-adjusted kidney cancer mortality rate ratios (RRs) for Region II compared with Region V started to increase about 10 years after high arsenic exposure began in 1958. There was an RR of 2.5 (95% confidence interval (CI) = 1.2-5.2) among men for the 5-year period centred in 1967, and an RR of 3.7

(1.8-7.6) for women for the 5-year period centred in 1972. For men, the peak kidney cancer mortality rate ratio was 3.4 (2.2-5.1) in 1981-1985, with a decline to 1.6 (1.2-2.1) in 1996-2000. For women, mortality RRs reached 2.9 (1.8-4.7) in 1981-1985 but remained higher for longer than men, with an RR of 4.4 (3.0-6.4) in 1991-1995 and then a decline to 2.3 (1.6-3.3) in 1996-2000. The effect of high arsenic exposure in early life was assessed by comparing young adults in Antofagasta and Mejillones aged 30-39 years (born during and just before the high-exposure period), and people aged 40 and above (born before 1950 and therefore without early life exposure). Standardised mortality ratios (SMRs) for kidney cancer mortality for these groups were calculated and compared with the rest of Chile. For those aged 30-39 years who had early life exposure, the SMR was 7.1 (3.1-14). For those aged 40 and above, the SMR was 3.1 (2.7-3.6). This 50-year mortality study showed a distinct increase in deaths from kidney cancer in both regions of Chile over the study period. However the pattern of increase for Region II showed a greater increase than Region V with a long latency relative to the period of high arsenic exposure. Increased kidney cancer mortality rate ratios continued for at least 25 years after the high exposure levels began to decline. The latency patterns are consistent with the causal interpretation and add strength to the epidemiological evidence that arsenic in water causes increased rates of kidney cancer mortality.

Disinfection Byproducts

Trihalomethanes in drinking water and the risk of death from colon cancer in Taiwan. Kuo HW, Tiao MM, Wu TN and Yang CY. (2009) Journal of Toxicology and Environmental Health - Part A: Current Issues, 72(20); 1217-1222. This study was conducted in Taiwan using total THM (TTHM) levels in public water supplies to examine the relationship between risks of colon cancer development with DBP exposure. There were 65 municipalities in Taiwan included in this study. Each municipality in Taiwan was assigned to a degree-of-urbanisation category from 1 (high) to 8 (low) based on variables such as population density, age



composition, economic activity and family income, education level, environment and health service-related facilities. Urbanisation index was used as a proxy for variables such as socioeconomic status and differential exposures to environmental conditions, which are related to the aetiology of mortality. Data was obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health on all deaths of Taiwan residents from 1997 through 2006. For each death, detailed demographic information was recorded including gender, year of birth, year of death, cause of death, place of death (municipality) and residential district (municipality). All eligible colon cancer deaths occurring in people between 50 and 69 years of age were the case group. The control group consisted of all other deaths excluding those deaths that were associated with gastrointestinal diseases. Controls were pair matched to cases by gender, year of birth and year of death. A national survey of TTHM levels in municipal drinking water was conducted by the Taiwan Environmental Protection Administration (EPA) in 2000 and 2002 with water samples collected quarterly from each municipality. As treatment practices have not changed over time in the study areas, the average TTHM levels of the two years were used as a measure of exposure levels for the municipalities in the study. The municipalities of all cases and controls were identified from the death certificate and were assumed to be their source of TTHM exposure via drinking water. The levels of TTHM of each municipality were used as an indicator of exposure to TTHM for an individual residing in that municipality. Subjects were categorised into one of three exposure categories according to the levels of TTHM in their drinking water: low (the lowest 50th percentile; less than 6.03 ppb), medium (50th-75th percentile; 6.03-14.80 ppb), and high (above the 75th percentile; above 14.80 ppb). There were 2185 colon cancer cases with complete records for the years 1997-2006. Subjects who were married had a significant excess risk of colon cancer in comparison to those who were single. Colon cancer cases occurred at higher frequency (60.2%) in individuals living in a metropolitan municipality than the controls (56.8%). The crude odds ratio (OR) and

95% confidence intervals (95% CI) for death attributed to colon cancer was 0.96 (0.83-1.12) for the group with medium TTHM exposure and 1.01 (0.87-1.17) for the groups with high TTHM exposure when compared to the group with low TTHM levels. Adjustment for possible confounders only slightly altered the OR. The adjusted ORs were 1.02 (0.87-1.2) for the group with medium TTHM levels and 1.04 (0.89-1.21) for the group with high TTHM levels when compared to the group with low TTHM levels. The ORs for death due to colon cancer were not significantly higher for the two groups with higher levels of TTHM in drinking water. This study showed no statistically significant association between TTHM levels in Taiwan’s drinking water and risk of death from colon cancer. No information was available on the quantity of water consumed by people at home or at other places, or on important risk factors for colon cancer development such as physical activity and meat and fat consumption. Future studies need to be conducted to increase the precision of estimates of individual exposure to TTHM and other factors.

Nitrate

Nitrate intake and the risk of thyroid cancer and thyroid disease. Ward MH, Kilfoy BA, Weyer PJ, Anderson KE, Folsom AR and Cerhan JR. (2010) Epidemiology, 21(3); 389-395. Thyroid cancer is the most common endocrine system malignancy and the eighth most common cancer among women. The incidence of thyroid cancer has increased substantially in the United States since 1980 for unknown reasons. Ingested nitrate inhibits the thyroid uptake of iodide and therefore potentially affects thyroid function. This study examined the relationship between nitrate intake from public water supplies and diet and the risk of incident thyroid cancer and prevalent hyperthyroidism and hypothyroidism. A questionnaire was mailed in 1986 to 98,030 randomly selected women in Iowa who were aged between 55 and 69 years. There were 41,836 women who participated in the initial survey which included



questions about demographics, anthropometry, reproductive history, hormone use, family history of cancer, residence location, physical activity, smoking, alcohol consumption and medical conditions. Also included was a 126-item semi-quantitative food frequency questionnaire. A follow-up questionnaire in 1989 included information about the participants’ usual source of drinking water and 36,127 women responded. Public drinking water supplies were the water source for 76% of women followed by private wells (18%) and bottled water or another source (6%). Of those women using public supplies, 85% used the supply for over 10 years and 70% used the supply for over 20 years. Women were excluded from the study if at baseline they reported cancer or if they did not respond to or died before the 1989 survey. Women were excluded if they used their public or private well supply for 10 years or less, if they lived in communities that were served by multiple water sources or communities for which no nitrate measurement data were available. The drinking water analysis cohort included 21,977 women, 73% who used a public water supply, 25% who used a private well and 2% who used bottled water or another source. For the dietary nitrate analyses, an additional 1326 women were excluded due to missing or presumed erroneous data. Nitrate levels in Iowa public water supplies were available from historical monitoring data but no nitrate measurement data were available for women using private wells. Women who were well-water users were compared with women using public supplies with the lowest quartile of nitrate to determine the association of private well use with thyroid cancer and conditions. The cohort was traced annually for cancer incidence by linking personal identifiers to the State Health Registry of Iowa’s cancer database. During the 19 years of follow-up, 45 cases of thyroid cancer were diagnosed. The median time from enrolment to diagnosis was 9.3 years. In the cohort 3151 women reported ever having hypothyroidism and 1009 reported ever having hyperthyroidism. There was little evidence for an association of thyroid cancer incidence with use of a private well as a drinking water source. However, for public water supplies, increased mean nitrate concentration was

associated with increasing risk of thyroid cancer (P for trend = 0.02). Compared with women in the lowest quartile, risk was elevated 2.2-fold (95% CI = 0.83-5.76) for the highest quartile. Risk was found to increase 2.6-fold (1.09-6.19) for the highest versus lowest category of years of use of a public water supply with nitrate levels greater than 5 mg/L (P for trend = 0.04). Increasing intake of nitrate from dietary sources was also found to be associated with increasing risk of thyroid cancer. The relative risk was 2.9 (1.00-8.11) for those in the highest versus the lowest quartile of dietary nitrate (P for trend = 0.046). No association was found between the prevalence of hypothyroidism and hyperthyroidism with either the mean nitrate concentration in public water suppliers or increasing years of nitrate levels greater than 5 mg/L. The use of private wells was not associated with risk of either condition. Increasing intake of nitrate from dietary sources was associated with increased prevalence of hypothyroidism (P for trend = 0.001). When those with the lowest intake were compared with those with the highest intake quartile, there was a 24% higher prevalence of hypothyroidism (95% CI = 1.10-1.40). There was no association found with hyperthyroidism. In this study nitrate ingestion from dietary and drinking water sources was associated with an increased risk of thyroid cancer which has not been seen in previous studies, and higher intake of dietary nitrate was associated with hypothyroidism. The findings for thyroid cancer were based on small numbers and larger studies are required to clarify the study findings and to evaluate the potential interaction between nitrate ingestion and factors that affect rates of endogenous nitrosation. The study results are biologically plausible and are consistent with animal data. As the incidence of thyroid cancer has increased during the past decades, with no identifiable cause, the possible role of nitrate needs to be considered in future epidemiological studies of thyroid cancer and thyroid conditions.

Outbreaks

A Cryptosporidium hominis outbreak in North-West Wales associated with low oocyst counts in treated drinking water.



Mason BW, Chalmers RM, Carnicer-Pont D and Casemore DP. (2010) Journal of Water & Health, 8(2); 299-310. This paper reports the results of an epidemiological investigation of an outbreak of cryptosporidiosis in North West Wales during 2005. This region normally has a low rate of notified laboratory-confirmed Cryptosporidium infections (36 cases in total for 2004), and suspicions of an outbreak were raised when 21 notifications were received during September/October 2005. Further cases continued to occur and an Incident Management Team was set up on 7 November. Preliminary investigations suggested a link with the drinking water supply derived from a reservoir (Llyn Cwellyn) which serves a resident population of around 60,000 people as well as numerous tourists. On 18 November, a precautionary reminder for severely immunocompromised patients to boil their water was issued. A general boil water notice was issued on 29 November. There were 231 laboratory-confirmed cases of cryptosporidiosis notified between 1 October 2005 and 31 January 2006 in the area. Of the 231 cases, 218 were confirmed as Cryptosporidium hominis infection by genotyping at the COWP locus. A case-control study was undertaken to examine whether Cryptosporidium hominis infection was associated with the consumption of unboiled tap water. Cases were those residents aged 16 years or older with diarrhoea (three or more loose stools in 24 hours) with an onset after 1 September. Cases were excluded if they had a history of travel outside the UK or contact with a household member with a history of diarrhoea, during the two weeks before onset. Controls were randomly selected from the same area and were 16 years or older, had no history of travel outside in UK in the two weeks prior to the 5 November, or contact with a household member with new onset of diarrhoea since 1 September. Cases and were interviewed using a structured outbreak questionnaire which collected information about a range of exposures. At the time of the outbreak, Llyn Cwellyn was classed as a low risk source for Cryptosporidium. Water treatment comprised pressure filtration and

chlorination, but there was no requirement to monitor for Cryptosporidium in finished water under drinking water regulations. Continuous monitoring for Cryptosporidium commenced on Cwellyn final water from 2 November as part of the investigation. The attack rate was found to be significantly higher in the population supplied by Cwellyn Water Treatment Works relative to other water sources (relative risk 4.1, 95% CI, 2.8-6.1, P less than 0.0001). There were 45 cases and 37 controls included in the case-control study. Drinking unboiled tap water was found to be significantly associated with disease, odds ratio 6.1, p = 0.002. There was a dose-response relationship found with increasing risk of disease with higher consumption of unboiled tap water. Age and the number of glasses of unboiled tap water drunk per day were the only significant variables in the multivariate analysis. The average number of oocysts per 10 litres per large volume (greater than or equal to 1,000 l) continuous sample in final treated water at the Cwellyn Water Treatment Works were consistently low and below the regulatory treatment standard (average of less than one oocyst per 10 litres in a continuous sample at 40 litres/hr/about 24 hrs) which is specified for sites identified as at significant risk of Cryptosporidium. However, oocysts were detected in 63% of samples from the plant. The shape of the epidemic curve suggests that it is unlikely that a large number of oocysts entered the distribution system prior to the commencement of continuous monitoring. No failure of water treatment was identified or any adverse event or challenge indicating a plant under strain. There were a number of potential sources of pollution including a sewage treatment works at the head of the lake and at least 13 septic tanks at properties in the catchment. Heavy rain was common in the area with rapid flows into the lake from water courses and intermittent flooding in low-lying areas. There were no effective barriers to Cryptosporidium either naturally occurring in the catchment or man-made in terms of water treatment. The boil water notice was in place for nine weeks until a UV treatment plant was installed at the Cwellyn WTW. This outbreak led to a major modification of the relevant water quality regulations



and also the setting up of a new multiagency liaison group in Wales, to coordinate the approach to any future incidents or outbreaks. This outbreak demonstrated that C. hominis outbreaks can occur in the presence of very low numbers of oocysts detected in treated water. The risk to human health only becomes apparent when this water is supplied to a large susceptible population and an outbreak results.

Pharmaceuticals

Human health risk assessment of carbamazepine in surface waters of North America and Europe. Cunningham VL, Perino C, D'Aco VJ, Hartmann A and Bechter R. (2010) Regulatory Toxicology and Pharmacology, 56(3); 343-351. Carbamazepine (CBZ) is a therapeutic pharmaceutical agent for the treatment of epilepsy, trigeminal neuralgia, bipolar depression, excited psychosis and mania. Since 1998, CBZ has been detected in sewage treatment plant (STP) influents, STP effluents, surface waters, drinking waters and groundwaters in Europe, the United States and Canada. CBZ’s greater frequency of detection may be because it appears to be more resistant to removal than other pharmaceuticals and is used in relatively high volumes. There is a considerable body of literature on its metabolism and pharmacology. A human health risk assessment was undertaken for environmental exposure to CBZ and two of its major metabolites, carbamazepine diol (CBZ-DioH) and carbamazepine N-glucuronide (CZB-N-Glu) in the aqueous environment. CBZ itself is the pharmaceutically active entity and of all its metabolites, only 10,11-epoxide (CBZ-EP) (comprising 1-2% of the excreted dose) can significantly add to the antiepileptic effect of CBZ in people. The major metabolite CBZ-DioH is inactive. There is no pharmacological data on CBZ-N-Glu, however as a highly polar metabolite it would not be expected to demonstrate any therapeutic activity. CBZ, CBZ-DiOH, and CBZ-N-Glu, which make up approximately 64% of the excreted dose, were the compounds selected for assessment. The Acceptable Daily Intake (ADI) represents a level of daily intake that should not result in an adverse human health

effect from direct exposure in a population, including individuals which are particularly sensitive. The ADIs for CBZ, CBZ-DiOH, and CBZ-N-Glu were estimated. The ADIs for CBZ-DiOH, and CBZ-N-Glu were set at 333 micro g/kg/day. The ADI for CBZ was 15.9 micro g/kg/day. The ADIs were combined with standard assumptions about potential exposure, via drinking water and fish consumption to derive predicted no effect levels (PNECs) for CBZ, CBZ-DiOH, and CBZ-N-Glu. Three different types of PNECs were derived for both children and adults: a PNEC protective of drinking water exposures only (PNECDW); a PHEC protective of fish consumption exposures only (PNECF); and a PNEC protective of combined drinking water and fish consumption exposures (PNECDW+F). The PNECs for children are more conservative for screening purposes than for adults as children are assumed to drinking more water and eat more fish per body weight than adults. Only the PNECs calculated for children were therefore presented. Combined drinking water and fish consumption human health PNECs for CBZ, CBZ-DiOH, and CBZ-N-Glu in children were 226,000, 4,760,000 and 4,760,000 ng/L respectively. Measured environmental concentrations (MECs) for CBZ in surface waters of North America and Europe were calculated. There were 2046 surface water MECs for CBZ from 52 references included in the analysis. Concentrations of CBZ reported for European surface waters range from non-detectable to 11,581 ng/L, while concentrations for Canadian and U.S. surface waters range from non-detectable to 1,500 ng/L. CBZ-DioH has been reported for one sample in Canadian surface waters at a concentration of 2.2 ng/L and from three rivers in Germany at a maximum concentration of 140 ng/L. The presence of CBZ-N-Glu has not been reported in surface water. CBZ in finished drinking water or drinking water source water has been found at levels from less than 0.8 to 258 ng/L . Predicted environmental concentrations (PECs) for CBZ, CBZ-DiOH, and CBZ-N-Glu in North American and European surface waters were estimated using the PhATE and GREAT-ER models, respectively. The PECs estimated using PhATE were compared with MECs reported for CBZ in North



American surface waters. The cumulative probability distributions of all MECs (n=464) and of PECs for all model segments (n=2710) at both low and mean flow conditions were calculated. The low-flow PECs from PhATE and GREAT-ER models were considered to be conservative estimates of exposure as compared with measured concentrations. In order to evaluate the potential human health risk associated with exposure CBZ, CBZ-DiOH, and CBZ-N-Glu, combined drinking water and fish consumption PNECs were compared with MECs and PECs. The results of these comparisons are expressed as margins of safety (MOS) or the ratio of the PNEC to the MEC or PEC. If the MOS is large (MOS greater than or equal to 1) then the measure or predicted concentrations are far below allowable concentrations. The MOS for CBZ, CBZ-DiOH, and CBZ-N-Glu in both North America and Europe were found to be high, ranging from 340 to 6560. These MOS indicate that there is no appreciable risk to human health from environmental exposures from drinking water and fish consumption. This analysis represents conservative assumptions and data. The MECs and PECs evaluated represented only surface waters, not drinking waters. For MECs in particular, many of the samples analysed came from areas expected to be impacted by sewage effluents, not from areas used for drinking water diversion. If the approach was refined and drinking water concentrations were taken into account, the MOS would probably increase. This assessment does not however consider the potential effects of mixtures.

POU Disinfection

Evaluation of a new disinfection approach: Efficacy of chlorine and bromine halogenated contact disinfection for reduction of viruses and microcystin toxin. Coulliette AD, Peterson LA, Mosberg JAW and Rose JB. (2010) American Journal of Tropical Medicine and Hygiene, 82(2); 279-288. Point-of-use (POU) or household water treatment (HWT) devices have been used in areas where there are insufficient funds or infrastructure to adequately treat drinking water. These devices use physical or

chemical means to reduce microbial threats and have been shown in a variety of studies to reduce bacteria, pathogenic viruses, protozoa and diarrheal illnesses. This paper describes a novel HWT system that delivers disinfection as the water passes through the device, by halogen oxidants that act as a contact biocide. The HaloPure halogenated N-halamine media is part of a commercially available larger water purifier called AquaSure. AquaSure is a gravity-fed system where water passes through a canister containing HaloPure media and the treated water is then collected. This study was undertaken to evaluate the HaloPure chlorine and bromine media for their ability to reduce microcystin toxins, and the bacteriophage MS2 (a coliphage) which was used as a proxy for enteric viruses. Three chlorine and three bromine AquaSure Water Purifier Units were set up with new HaloPure halogenated canisters according to manufacturer’s directions. The cloth and granulated activated carbon filters were removed for this study to test for the effectiveness of HaloPure disinfectants without interference from other virus/toxin removal sources. Non-chlorinated well water was seeded with either bacteriophage or microcystin toxin for their respective challenges. The seeded water was poured into the upper reservoir of the water purifier. Effluent samples were collected every 15 minutes (15, 30, 45, 60, 75 and 90 min) for the bacteriophage experiments and at 5, 10, 20 and 30 minutes for the microcystin experiments. In the bacteriophage trials, three canisters were tested for the chlorine (C1, C2 and C3) and bromine (B1, B2 and B3) systems and samples were run in triplicate. For the microcystin trials, two canisters were tested for the chlorine (C1, C2) and bromine (B1, B2) systems and samples were assayed in duplicate. Free and total chlorine and bromine residuals were analysed for all the bacteriophage challenges in samples collected at one hour and at the end-of-flow time points. The chlorine HaloPure canisters resulted in an overall average log10 reduction for bacteriophage for all three units of 4.86 plus or minus 0.70 (n=147). The bromine HaloPure canisters resulted in an overall average log10 reduction for bacteriophage of 5.02 plus or minus 0.19 (n=84). The bromine system



achieved reductions for bacteriophage of greater than or equal to 99.99% (4 logs) (EPA standard for virus removal for water purifiers) for all of the trials. For all of the units, there was a slight increase in the bacteriophage reductions with increased time in the unit. The chlorine system overall met the EPA standard for virus removal for POU systems (greater than 99.99% or 4 logs) 44.4% of the time. Overall the microcystin toxin concentration was reduced by 27.5% and 88.5% to final concentrations of 1,600 (plus or minus 98) ng/L and 250 (plus or minus 50) ng/L for the chlorine and bromine canisters, respectively. After five minutes time, only small reductions of toxin in the effluent were observed. With increasing time within the unit, no statistical significance could be shown, although there was a slightly downward trend of approximately 10-20%. Microcystin was reduced to below the WHO toxin standard (1,000 ng) in 0% and 100% of all trials for the chlorine and bromine systems, respectively, with an average influent concentration of 2,222 ng/L. The total chlorine residual was 0.48 plus or minus 0.01 mg/L (n=18) and the total free chlorine residual was 0.24 plus or minus 0.03 mg/L (n=18) for the chlorine HaloPure systems during the bacteriophage experiments. These values were found not to change significantly over the course of the experiment. The average total bromine residual was 1.21 plus or minus 0.07 mg/L for the bromine HaloPure system during the course of the bacteriophage experiments. The bromine HaloPure canister showed more consistent results when compared with the chlorine canister in reducing concentrations of bacteriophage and microcystin toxin. More research should focus on the use of bromine-based disinfectants for the disinfection of drinking water. One of the main advantages of using bromine versus other halogens, such as iodine and chlorine, is that humans tolerate bromine residuals at higher levels and this enables better protection of treated water during storage. The HaloPure system does not require users to add the disinfectant, removing a potential source of error, and could have a higher rate of sustainability. The cost of producing water using N-halamine technology is comparable to municipally treated water.

Rainwater

Analysis of first flush to improve the water quality in rainwater tanks. Kus B, Kandasamy J, Vigneswaran S and Shon HK. (2010) Water Science and Technology, 61(2); 421-428. This study is part of a project that aims to develop a cost effective in-line filtration system to improve water quality in rainwater tanks. The aim was to quantify the concentration of pollutants in the first flush of roof runoff flowing into rainwater tanks. Sampling was conducted on a typical rainwater tank located at an urban residential property in the South Western suburbs of Sydney. The Sydney Basin is a “closed” geographical basin where pollution generated from primary sources (industry, road transport, etc.) collects from early morning. Onshore afternoon sea breezes, normally from the north-east, concentrate air pollution in the South Western suburbs. The rainwater tank studied was less than one year old and collected water off concrete roof tiles from a 30 year old house. The glaze on the tiles had worn off and there was no lead flashing on the roof. The house is part of a residential suburb that is located near an industrial area and a freeway. The rainwater tank is made from polyethylene and is plumbed using PVC pipe and fittings from the aluminium gutter to the tank. Three rainfall events were analysed that complied with the following conditions: a previous significant storm event washed the roof; at least a two-week dry period followed the significant storm event; adequate and consistent rainfall occurred after the two-week dry period to enable at least 3 mm of first flush sample to be collected for analysis. Samples were collected from the downpipe approximately every 2.5 min after the start of the storm for up to 25 min. Total rainfall in mm was determined at the time of collection of each sample by a rain gauge on site. Samples were taken directly from the downpipe from the gutter before the first flush system. Samples of rainfall were also taken before the rain came in contact with the roof to obtain the concentration of pollutants in rainfall.



Water samples were analysed to determine individual pollutants in the first flush. The heavy metals analysed included: aluminium, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium, silver and zinc. The mineral salts analysed were calcium, magnesium, chloride, potassium, sodium and sulphate. Other parameters measured included: nitrate and nitrite, pH, ammonia, orthophosphate, conductivity, hardness, turbidity, total suspended solids, total dissolved salts and bicarbonate. Samples of the first flush roof runoff from one rainfall event were analysed for rainwater organic matter (RWOM) in terms of molecular weight distribution (MWD) using high performance liquid chromatography. All samples of total suspended solids and water hardness were below the Australian Drinking Water Guideline (ADWG) limit of 400 mg/L and 200 mg/L (CaCo3 equivalent) respectively. Conductively was also well below the ADWG limit of 0.8 dS/m. For turbidity to be reduced to 5 NTU which is specified in the ADWG, approximately the first 5 mm of rainfall needs to be bypassed. The ADWG limits of 0.3 and 0.1 mg/L for iron and manganese, respectively, were exceeded in runoff from the first 1 to 1.5 mm of rainfall. The ADWG limit of 0.2 mg/L for aluminium was exceeded also in the first 1.5 mm of rainfall coming off the roof. The lead levels were of most concern with levels exceeding the ADWG limit of 0.01 mg/l until runoff from the first 5-6 mm of rainfall was bypassed. The concentration of lead in the rainwater before contact with the roof was 0.02 mg/l. The other metals such as arsenic, cadmium, chromium, copper, mercury, nickel, selenium and silver were either not detected or were at levels less than 0.002 mg/L. The levels of ammonia were above the ADWG limit of 0.5 mg/L in roof runoff during the first 1.5 mm of rainfall. Nitrate, nitrite and orthophosphate concentrations did not show any consistent pattern and varied randomly with ongoing rainfall. The initial flushing carried the majority of organic contaminants and the concentration of organic matter decreased with further runoff. After 2 mm of continuous roof runoff, the intensity of the MWD peaks reduced to the extent that it began to resemble results for rainwater that had not come in contact with the roof.

It was concluded that for most parameters, the quality of the collected water is suitable for drinking when compared with the ADWG after bypassing the first 2 mm of rainfall. Turbidity and lead however, required approximately the first 5 mm of rainfall to be bypassed to meet the ADWG guideline in runoff. It was found from the MWD analysis that diverting the first flush of a roof significantly improves the water quality of the rainwater collected in the tank and significantly reduces the treatment and energy requirements for filtration.

Sporadic Disease

Enteric illness risks before and after water treatment improvements. Frost FJ, Tollestrup K, Roberts M, Kunde TR, Craun GF and Harter L. (2009) Journal of Water and Health, 7(4); 581-589. Drinking water regulators in the US and elsewhere are concerned about both endemic and outbreak waterborne disease risks in susceptible subpopulations such as the elderly and young children. There are new requirements for unfiltered surface water supplies, even if they are in protected watersheds, which may involve water utilities filtering the water unless they can consistently maintain a very high water quality. The health benefits from new technologies such as filtration and ozonation at water treatment plants have not been extensively studied, even though they can effectively remove and inactivate Giardia and Cryptosporidium oocysts. Results from randomised household intervention studies evaluating home drinking water filtration systems have been conflicting. This study was conducted to evaluate whether acute gastrointestinal illness risks declined after filtration and ozonation were added to an unfiltered but chlorinated surface water source which came from well-protected watersheds with no evidence of human sewage contamination. The only human pathogens that were known to be present in the source water were Cryptosporidium and Giardia probably from wild animals as there was no livestock grazing in the catchment.



This prospective cohort study was conducted in two geographic areas (control and intervention) in a north-western U.S. city during two time periods: phase 1 from June to November 2000 and phase 2 from June to November 2001. The intervention and control sites were in the same city and were served by one water utility. Each site however was supplied by a different unfiltered, chlorinated surface water source. Both surface water sources were from well-protected watersheds with no source or evidence of human sewage contamination. Treated water from both sources was stored in uncovered, secured and monitored distribution system reservoirs. Both water sources were chlorinated over the whole study period and drinking water met the current US Environmental Protect Agency (EPA) Safe Drinking Water Standards for coliform bacteria. Before the beginning of phase 2, a new water treatment facility was completed at the intervention site. Treatment included ozone for primary disinfection, coagulation/flocculation, high-rate granular filtration and chlorine as a secondary disinfectant. Fluoride and chemicals for corrosion control were added also. Following filtration, turbidity in the intervention site declined. The control site had no change in treatment. Families were recruited from both sites and were eligible to participate if: 1) a household member included either a child aged 2 to 10 years or an adult at least 65 years of age; 2) the household drank municipal water and did not have a home filtration system; and 3) family members had lived in the residence for at least six months and planned to stay in the community for the next two years. The family needed to live in an area where the water came from only one source. A designated person from each family recorded illness for each member in a daily illness diary for each 6-month period in phase 1 and phase 2. The daily diary recorded whether each person was out-of-town, was well or had diarrhoea (loose/watery stools), vomiting, nausea or other symptoms of colds etc. There were four categories of illness defined: diarrhoea (at least two episodes of soft or loose stools), gastrointestinal illness (having nausea, any vomiting or abdominal cramps), highly credible gastrointestinal illness (HCGI) (at least one of the following: vomiting or liquid diarrhoea or nausea or diarrhoea combined with abdominal

cramps) and other illness (fever, chills, headache or cold without enteric symptoms). Symptoms occurring within five days of each other were considered to be related and counted as one episode, if 6 or more days had elapsed without diarrhoea or gastrointestinal symptoms then it was counted as a new episode. There were 906 participants from the intervention site and 471 from the control site. The analysis included 711 participants from the intervention site and 361 from the control sites who successfully completed both study phases. For both the intervention and control sites, the mean number of reported illnesses in each category per diary-year declined for all age groups during phase 2, except for a slight increase in HCGI in participants aged 20-64 in the intervention group. The decline in illness rates was greater in those less than 20 years and in those 65 years and older. There was only a relatively small decline in gastrointestinal and diarrhoea illness rates for the 20-64 year age intervention group. Unadjusted incidence density ratios (IDRs) for phase 2 were calculated comparing the control and intervention sites for the four categories of illness. For any of the four illness categories there was no significant elevation of the IDRs. Unadjusted IDRs were calculated for the age groups and compared with participants age 2-19 years and both older age groups (20-64 years and 65 plus years) were at higher risk of diarrhoea in phase 2 (IDRs of 1.99 and 1.45). Participants aged 20-64 were also at a slightly higher risk of HCGI compared with the younger age group (IDR 1.03). Participants having three or more diarrhoea episodes in phase 1 had a fivefold higher risk of diarrhoea episodes compared to those who had less than three episodes in phase 1. A similar magnitude of increased risk was also found for gastrointestinal illness (IDR 4.90) and HCGI (IDR 4.32) and other illness (IDR 2.73) was also increased. Adjusted IDRs were calculated to examine the effect of the intervention as both age and number of illness episodes were related to an elevated IDR. The effect of the intervention was examined for participants with less than three episodes of illness in phase 1 and for participants with three or more episodes of illness in phase 1. IDRs were not significantly elevated or reduced for any of the four types of illness comparing



the intervention site and the control site for participants with less than three illness episodes in phase 1. However, for participants with three or more episodes of illness in phase 1, IDRs were elevated in the intervention area for all four types of illness (although not significantly for gastrointestinal and other illnesses) and were 1.16 for other illnesses, 1.86 for gastrointestinal illnesses, 2.23 for diarrhoea and 2.67 for HCGI. Overall, no differences were found in the risk of any of the illnesses after the new water treatment plant was completed. This study suggests that prior gastrointestinal illness history or the propensity to report the illness may be a significant risk factor for increased risk of current reported gastrointestinal events. The risk of the occurrence of future gastrointestinal, diarrhoea and other illness episodes therefore may be strongly dependent on individual characteristics and/or susceptibility such as age or prior illness rates. Other studies have hypothesised that improved water quality may actually reduce the protective immunity to Cryptosporidium and result in higher rates of illness with gastrointestinal symptoms and diarrhoea. Evidence from this study is insufficient to conclude that elevated risks in phase 2 were due to decreased levels of protective immunity and further studies using high-risk immunosuppressed populations need to be conducted. Also, exposure to Cryptosporidium oocysts and other enteric pathogens can occur from sources other than drinking water (water recreation, raw fruit and vegetable consumption) and these exposures may help to explain the increased risks. Where's the pump? Associating sporadic enteric disease with drinking water using a geographic information system, in British Columbia, Canada, 1996-2005. Uhlmann S, Galanis E, Takaro T, Mak S, Gustafson L, Embree G, Bellack N, Corbett K and Isaac-Renton J. (2009) Journal of Water and Health, 7(4); 692-698. Waterborne disease outbreaks have been well documented however little is still known about sporadic cases of waterborne disease. This cross-sectional analysis was undertaken at the individual level to assess whether the risk of sporadic enteric

disease differs by drinking water source (surface or ground water) and type (municipal or private) using surveillance data and a geographic information system (GIS). In addition, the methodology used here was evaluated to see whether it was efficient, practical, affordable and well received and therefore was of potential use by municipal governments. This study was undertaken in Community A (97,000 residents) located within Greater Vancouver, British Columbia (BC), Canada. Of the community’s residents, 63% relied on a mix of municipal surface water and municipal ground water for their drinking water, 19% were served by a municipal ground water system only, and 18% relied on ground water from private wells. The municipal surface water was treated by chlorination and ozonation, municipal ground water was chlorinated and both were tested according to the provincial guidelines. Ground water from private wells is usually untreated and not tested. In British Columbia, all laboratory-confirmed cases of potentially waterborne disease legally have to be reported. For the years 1996-2005, all laboratory-confirmed cases of campylobacteriosis, cryptosporidiosis, giardiasis, salmonellosis and verotoxigenic E. coli infection (VTEC) were included if the address of the case was in Community A at the time of disease. Cases were geocoded by street address and were mapped according to the residence they lived in at the time of reported illness. Information on land parcel-specific drinking water data for Community A were obtained from municipal, provincial and federal government and local health authority data and from environmental assessments commissioned by the community. Each land parcel on the map consisted of all water source information for that residence, by year. Each land parcel was assigned to one of three water systems: municipal mixed (surface and ground) water, municipal ground water, or private well water, on the basis of the year of reported disease. Between 1 January 1996 and 31 December 2005, there were 957 cases of the selected infections among residents of Community A. After exclusion of non-locally acquired cases, 840 cases remained. Of these 840 cases, 814 were successfully geocoded and had their drinking water system identified, representing



797 individuals (17 people had two episodes of disease). Of the total cases, campylobacteriosis cases made up 57%. Ten year average rates by disease were highest for campylobacteriosis (52 per 100,000), followed by salmonellosis (16 per 100,000), giardiasis (14 per 100,000), VTEC infection (6 per 100,000) and cryptosporidiosis (5 per 100,000). For all five diseases, rates were highest for residents of land parcels serviced by private wells, followed by those served by the municipal mixed water system. The risk of disease for those with private wells was significantly higher than for those served by the municipal ground water systems for all ten years examined. The risk of disease for those on the municipal mixed water system was significantly higher than those on the municipal ground water systems for the years 1997, 2002 and 2003. Ten-year average risk ratios were calculated for each system and the risk of disease was 5.2 times higher for those serviced by private wells and 2.3 times higher for those serviced by the municipal mixed water systems than those on the municipal ground water system. When campylobacteriosis cases were examined separately, the risk of disease was 8.1 times higher for those on private wells and 3.4 times higher for those on the municipal mixed water system, compared to the municipal ground water system. For the other four diseases combined, ten-year average risk ratios were 4.5 times higher for those serviced by private wells and 1.9 times higher for those serviced by municipal mixed water system, than for those on the municipal ground water system. Rates for those serviced by private wells were significantly higher than rates for the two municipal systems combined for all ten years except 2001 (ten year average RR = 2.7). The findings of this study provide evidence that people who live on land serviced by private wells may be at greater risk of enteric diseases. This may be due to the proximity of wells to livestock; Community A has more farms than any other municipality in BC. Poultry and cattle are known reservoirs for all of the pathogenic organisms considered in this study. Wells which have deteriorated and/or are poorly constructed are especially susceptible to contamination from surface

runoff or ground water. The results found here also suggest a risk gradient where untreated water poses a higher risk of disease than treated water and disinfected but unfiltered surface water poses a higher risk than treated ground water. This study emphasises the importance of adequate private well construction and maintenance, including testing and treatment. In Community A there is currently a program to educate well owners and to help them properly maintain and test their wells. This study also highlights the usefulness and efficiency of using a GIS to estimate population level risk factors for sporadic cases of enteric disease.

Water Hardness

Relationship between tap water hardness, magnesium, and calcium concentration and mortality due to ischemic heart disease or stroke in the Netherlands. Leurs LJ, Schouten LJ, Mons MN, Goldbohm RA and Van Den Brandt PA. (2010) Environmental Health Perspectives, 118(3); 414-420. An evaluation published in 2007 of the epidemiological evidence on the effects of calcium and magnesium in drinking water on cardiovascular disease rates, concluded that the available evidence was not sufficiently strong to infer that low levels of calcium or magnesium in drinking water are significant factors in the causation of cardiovascular disease. However a meta-analysis of case-control studies published in 2008 found evidence of a significant inverse relationship between magnesium levels in drinking water and cardiovascular mortality. Due to the inconclusive results of previous studies, this study was conducted to investigate the association between water hardness and ischaemic heart disease (IHD) or stoke mortality in the ongoing Netherlands Cohort Study (NLCS). This is a large prospective cohort study on diet and cancer that began in 1986 with a total of 58,279 men and 62,573 women between 55 and 69 years. Emerging cases were collected from the whole cohort whereas accumulated person-years in the cohort were estimated from a subcohort. A subcohort of 5,000 subjects from the NLCS was randomly sampled



immediately after baseline. At baseline, all cohort members completed a self-administered questionnaire on dietary habits, beverage consumption, anthropometry (weight and height) and other risk factors related to cancer and the presence of cardiovascular disease. There was a 150-item semi-quantitative food-frequency section of the questionnaire which concentrated on habitual consumption of food and beverages during the year preceding the start of the study. Information on intake of minerals was collected from this food-frequency section of the questionnaire. Data on calcium and magnesium concentrations in tap water was obtained in 1986 from all of the 364 pumping stations in the Netherlands. The calcium and magnesium concentrations of tap water were estimated for each home address by postal code. Tap water hardness was categorised as soft (less than 1.5 mmol/L calcium carbonate), medium hard (1.6-2.0 mmol/L calcium carbonate) and hard (greater than 2.0 mmol/L calcium carbonate). The 1986 information linking postal code and pumping station was verified for 1996 (the end of the investigation period) by the water companies as several pumping stations had introduced pellet softening in this period. Mortality data were obtained between January 1978 and December 1996 by linking the NLCS database to the Central Bureau of Genealogy. There were 18,091 deaths identified in this period. Of all deaths, 6,735 were primarily related to cardiovascular disease. A multivariate case-cohort analysis was conducted based on 1,944 IHD mortality cases and 779 stroke mortality cases and 4,114 subcohort members. In 1986 in the Netherlands, tap water calcium and magnesium concentrations ranged from 15 to 157 mg/L and from 1.7 to 26.2 mg/L, respectively. Among the subcohort members, 36% lived in an area with soft water, 26% received medium hard water and 38% received hard tap water. In both the age-adjusted and multivariate analysis, no association was found between the concentration of calcium and magnesium in tap water or the total hardness of the water and IHD mortality or stroke mortality among men or women. When the analysis was restricted to those with the 20% lowest dietary magnesium intake (upper limit of the lowest quintile = 285 mg/day for men and 255 mg/day for women), no statistically

significant relationship between increasing intake of magnesium from tap water and IHD mortality among men or women was found. For stroke mortality, a statistically significant inverse association was found among men in the fourth quintile versus the first quintile (beneficial association with higher levels of magnesium in water) whereas for women the opposite was found (adverse association with higher magnesium levels in water). When the analysis was restricted to subjects with the 20% lowest dietary calcium intake, no associated was found between the calcium concentration in tap water and IHD mortality or stroke mortality in either men or women. The results from this study obtained in subjects with low dietary magnesium intake need to be interpreted with caution as results were opposite for men and women and this has not been previously reported, the number of cases and person-years on which this sub-analysis was based was limited and no other studies have analysed the relationship between tap water magnesium concentration and cardiovascular mortality in a subpopulation with low dietary intake. In the general population, food consumption contributes significantly more than tap water to the total intake of calcium and magnesium. It has been suggested however that waterborne magnesium is more easily absorbed by the body than dietary magnesium. Further research is required to examine the effect of tap water magnesium on IHD mortality or stroke mortality among men and women with low dietary magnesium intake.

Water Quality

Supply system factors associated with microbiological drinking water safety in regional New South Wales, Australia, 2001-2007. Cretikos M, Byleveld P, Durrheim DN, Porigneaux P, Merritt T. and Leask S. (2010) Journal of Water & Health, 8(2); 257-268. Microbiological contamination of drinking water poses an ongoing risk of sporadic gastrointestinal illness and a risk of gastrointestinal disease outbreaks. Illness due to drinking water can lead to substantial morbidity and mortality, community anger and detrimental economic impacts. The



Australian Drinking Water Guidelines (2004) are used in Australia as a model of best practice and provide a risk management framework for drinking water supply systems which includes a multiple barrier ‘catchment-to-tap’ approach. The Guidelines also recommend the use of Escherichia coli as the main indicator of microbiological contamination. Since 2001, a drinking water monitoring program has been operating in New South Wales. Drinking water samples are taken from taps in public locations and private residences within the distribution system and are representative of the water quality supplied to the consumer. Each water utility is responsible for monitoring its supply system and the NSW Department of Health provides testing for bacteria and health-related chemicals in the samples free of charge. The minimum number of drinking water samples that should be used for each water supply system to monitor its drinking water quality is recommended by the NSW Department of Health. Drinking Water Monitoring Program data were reviewed for sampling adequacy and microbiological compliance to assess the safety of public drinking water supplies in regional NSW. The review included all public drinking water supplies in NSW, apart from the large metropolitan drinking water supply systems operated by Sydney Water Corporation and Hunter Water Corporation, which have separate monitoring. Also excluded from the analysis were private (independent, non-water utility) drinking water supplies and Aboriginal communities with independent drinking water supplies. Data from the NSW Drinking Water Database were used for samples collected from 1 January 2001 to 30 June 2007, inclusive. The adequacy of microbiological sampling was assessed by comparing the number of samples tested for E. coli or thermotolerant (faecal) coliforms with the number of microbiological samples allocated to each supply system annually, which is based on the minimum sampling frequency recommended in the Guidelines, the population served and the complexity of the system. Microbiological compliance was assessed by calculating the proportion of samples in which E. coli were detected. The association between supply system characteristics, time period and monthly microbiological non-compliance for each supply

system was modelled for the review period using negative binomial generalised estimating equations with adjustment for autocorrelation and clustering The quality of drinking water in regional NSW was reviewed for 323 supply systems and their 110,278 microbiological samples. There were 3186 samples tested for thermotolerant coliforms only and 107,092 samples tested for E. coli alone or in combination with thermotolerant coliforms. Most of the supply systems submitted an adequate number of samples for microbiological testing of drinking water quality when compared with NSW Department of Health recommendations. The smaller supply systems were significantly more likely to under-sample for microbiological quality than larger supply systems (p less than 0.001, non-parametric trend test). There were 272/323 supply systems that submitted fewer than their allocated number of microbiological samples for testing over the review period. There were almost 40% (129/323) of regional drinking water supply systems that did not comply with the Australian Drinking Water Guidelines during 2001-2007, as E. coli was detected in over 2% of microbiological samples. There were 25% of regional drinking water systems that registered rates of E. coli detection of more than twice the guideline value during the review period. Smaller supply systems were significantly more likely to have higher rates of E. coli detection (p less than 0.001, non-parametric trend test). The median overall rate of E. coli detection for the study supply systems was 1.37 per 100 samples (IQR 0.31-4.07 per 100 samples). There was a significant improvement in microbiological compliance from 2001 to mid-2007. There was a statistically significant association between all the drinking water supply system features and microbiological non-compliance in the univariate analysis. Smaller supply systems, watercourse and groundwater, undisinfected and ultraviolet disinfected systems and higher mean turbidity levels were all associated with increased risk of microbiological non-compliance. Lower microbiological non-compliance levels were associated with higher mean free chlorine residual levels. The strongest association with non-



compliance was found for supply systems serving populations of fewer than 500 people, undisinfected systems and sedimentation only systems. Microbiological non-compliance was significantly associated with sampling year with a significant trend of improved compliance over the review period. Greater non-compliance was associated with autumn, spring and summer each year, with summer periods associated with over three times the incidence of microbiological non-compliance than winter periods (June to August). There was a statistically significant association between microbiological non-compliance and the supply system population, water source, disinfection method and mean turbidity levels in the multivariate analysis. For each 1,000 person increase in the size of the supply system population, there was a 1% reduction in risk of microbiological non-compliance (p =0.01). The strongest association with microbiological non-compliance was found in undisinfected supply systems, with an incidence of non-compliance over 12 times higher than for disinfected systems (p less than 0.001). Ultraviolet disinfection was the worst of all disinfection methods and was almost three times worse than chlorinated

systems. After controlling for disinfection method, groundwater was the lowest risk water source. Watercourses had a risk of non-compliance 2.3 times that of groundwater. Mean turbidity also remained significant and presented a 17% increased risk for each one nephelometric turbidity unit increase in mean monthly turbidity. This review showed that drinking water systems that are not disinfected and systems that serve small populations are particularly vulnerable to the effects of faecal contamination. Even in developed countries such as Australia where drinking water monitoring programs operate, the presence of E. coli above guideline levels in almost 40% of regional public drinking water systems in New South Wales, indicates that there is still a risk of outbreaks of waterborne disease in regional areas. Each water utility needs to fully implement a preventive risk-management framework to protect the community from drinking water associated risks.

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Health Stream is the quarterly newsletter of Water Quality Research Australia. Health Stream provides information on topical issues in health research which are of particular relevance to the water industry, news and updates on the recent literature. This newsletter is available free of charge to the water industry, public health professionals and others with an interest in water quality issues. An electronic version of the newsletter and a searchable archive of Health Stream articles are available via the WQRA Web page. Summaries of Web-bonus articles are available only in the electronic version. To be placed on the print mailing list for Health Stream please send your postal address details to: Pam Hayes Phone +61 (0)3 9903 0571 Epidemiology and Preventive Medicine Fax +61 (0)3 9903 0556 Monash University - SPHPM Email [email protected]

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WQRA HealthStream - Issue 58