INFORMATION AND ANALYSIS FOR WATER AND HEALTH PROFESSIONALS
Issue 51
Public Health Newsletter of the CRC for Water Quality and Treatment
In this Issue:
UK Cryptosporidium Outbreak
UK Cryptosporidium Outbreak
1
US Waterborne Outbreaks 2005-2006
2
Boil Water Alerts In Queensland
6
UK NDMA Survey
7
Lead In NSW School Rainwater Tanks
8
News Items
8
From The Literature
9
A contamination incident apparently caused by a single rabbit gaining access to a water tank has resulted in a boil water alert for 250,000 people in the East Midlands region of England. Anglian Water issued the alert on 25 June in consultation with the local Health Protection Unit after Cryptosporidium oocysts were detected during routine water quality monitoring at the Pitsford Water Treatment Works. This treatment plant draws its water from a large surface reservoir which is open to the public for recreational uses including fishing, sailing and windsurfing. According to information on the Anglian Water website, water from such surface water sources is treated by clarification, filtration, ozonation and granular activated carbon, then disinfected before distribution to customers. The level of Cryptosporidium oocysts detected in treated water has not been disclosed, and it is not clear whether the Drinking Water Inspectorate regulatory limit of 1 oocyst per 10 litres of water was exceeded. Consumers were advised that all tap water used for drinking, preparing food or cleaning teeth should first be boiled, however unboiled water was safe for washing, bathing and toilet flushing.
Web Bonus Articles Arsenic Disinfection Byproducts Fluoride Legionella Nitrate Organic Wastewater Contaminants Pathogenic E. coli Petroleum Plastic Pipes Water Contamination Incidents Mailing List Details
20
Editor Martha Sinclair Assistant Editor Pam Lightbody
CRCWQT Internet Address: www.waterquality.crc.org.au A searchable Archive of Health Stream articles, literature summaries and news items is available on the CRC Web page.
HEALTH STREAM
September 2008
After discovery of the contamination, Anglian Water undertook an intensive investigation and sampling program at the treatment plant. On 27 June the company announced that a part of the treatment process had been identified as the source of contamination, and that this had been isolated so that uncontaminated water was now being produced. In addition, a flushing and monitoring program was being carried out in the distribution system to ensure that any contaminated water was cleared from the system before the boil water notice could be lifted.
SEPTEMBER 2008
PAGE 1
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
The company also announced that it would install UV treatment at the plant as an additional barrier against future Cryptosporidium incidents. The boil water notice was lifted for the entire water supply area on 4 July when commissioning of UV equipment was completed. During the 10-day incident Anglian Water supplied approximately 95,000 litres of bottled water per day to hospitals, nursing care homes, schools and vulnerable individuals. A “WaterCare” register already existed prior to the incident for voluntary registration of vulnerable customers (such as people with visual or hearing impairments or those who require a constant water supply for medical reasons), in the event of a water emergency however only about 300 people were registered. After the boil water notice was issued a further 2,700 people joined the register. Anglian Water has announced it will make goodwill payments to customers for an amount equivalent to the cost of 6 weeks water supply charges or a maximum of 30 pounds as compensation for the disruption caused by the contamination incident. The oocysts detected in the water supply were sent for genetic analysis to the Cryptosporidium Reference Unit of the Health Protection Agency, and on 3 July it was announced that preliminary analysis had indicated the oocysts were of a type with low infectivity towards humans. On 14 July Anglian Water confirmed that the source of contamination had been traced to a small rabbit which had “gained access to the treatment process via a remote ancillary tank”. The animal was carrying Cryptosporidium of a genotype found previously in rabbits in China and Europe. To date there have been no literature reports of this genotype causing infections in humans. The majority of human Cryptosporidium infections are attributable to C. hominis (believed to be confined to humans) or C. parvum (transmissible between humans, cattle and sheep). A number of other Cryptosporidium genotypes/species have been reported at a low frequency, especially in people with impaired immune function. In parallel with the investigation of the water supply, the Health Protection Agency began investigating
HEALTH STREAM
reports of illness potentially linked to the water supply contamination. According to newspaper reports as many as 700 people had reported symptoms of gastrointestinal illness to their doctors, but given the size of the population in the affected area and the common occurrence of gastroenteritis in the community from multiple different causes it is believed that many of these cases may be unrelated to the water contamination incident. Despite the initial belief that the risk of human infections was low, a total of 23 human cases of Cryptosporidium infection of the rabbit genotype have been confirmed to date, and a number of faecal specimens are still being analysed. According to reports released so far by the Health Protection Agency, only one Cryptosporidium-positive specimen has been ruled out by genotyping as being attributable to the water contamination incident. This specimen was positive for C. hominis and came from a case with a reported onset date of 24 June, which is not consistent with the 3-10 day incubation period usually seen with Cryptosporidium infections. The rabbit genotype has not previously been reported as a cause of human Cryptosporidium infections, however phylogenetic analysis has shown it is very closely related to C. hominis and C. parvum. The incident will be investigated by the Drinking Water Inspectorate which will determine whether legal action should be taken against the water company.
US Waterborne Outbreaks 2005-2006 The Centers for Disease Control and Prevention (CDC) recently published two surveillance reports on water-related disease occurring in the United States during the period 2005 to 2006 (1, 2). One report covers outbreaks and case reports for drinking water and water not intended for drinking, while the second covers outbreaks and case reports associated with recreational water use. The summaries are compiled from reports submitted by state public health departments to the CDC under a voluntary national surveillance system that began in 1971. The scope of the surveillance scheme has been progressively broadened over time from the initial focus on drinking water supplies, to include
SEPTEMBER 2008
PAGE 2
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
recreational water outbreaks (since 1978), outbreaks related to water not intended for drinking, water exposures in occupational settings, and commercially bottled water (since 1999), and outbreaks from contaminated ice and beverages made with contaminated water, contaminated beverages from plumbing failures in drink mix/soda machines, and drinking water contaminated at the point of use (since 2003). Outbreak reports are assessed with respect to the quality of evidence linking the outbreak to a water exposure, and the nature of identified deficiencies in the components of the water supply system. The latest reports incorporate some changes to definitions compared to previous reports in the series: • the definition of an outbreak has been modified to “two or more epidemiologically linked cases” rather than also including single cases of specified diseases and conditions. Due to their health significance these single cases (primary amoebic meningitis caused by Naegleria fowlerii, cases of Vibrio infection and adverse effects from chemical exposures) are still reported but no longer classified or analysed as outbreaks. • for drinking water related outbreaks, an additional deficiency classification has been added to cover instances where a chemical contaminant occurs in source water and the existing water treatment process is not designed to remove this contaminant. • for the first time some information on adverse health events arising from chemical accidents at swimming pool facilities has been included where exposure did not occur via recreational water use, but these events have not been classified or analysed as outbreaks. Drinking Water Twenty outbreaks associated with drinking water were reported to have occurred during 2005 and 2006. These included ten outbreaks of acute respiratory illness (ARI), nine outbreaks of acute gastrointestinal illness (AGI) and one outbreak of Hepatitis A. This is the first two-year surveillance period in which ARI outbreaks have outnumbered AGI outbreaks since reporting of Legionella outbreaks began in 2001. All ten outbreaks of ARI
HEALTH STREAM
were attributable to Legionella species. A total of 43 ARI cases were recorded and four deaths were associated with these outbreaks. All of the outbreaks were associated with Legionella growth in the plumbing systems of buildings, with eight outbreaks occurring in healthcare settings (hospitals or longterm care facilities). A range of pathogens were identified in AGI outbreaks, including Norovirus (2 outbreaks), Campylobacter (1), Cryptosporidium (1), Giardia intestinalis (1), mixed Norovirus and Campylobacter jejuni (1) and mixed E.coli O157, E.coli O145 and C. jejuni (1). In the two remaining AGI outbreaks the causative agent was not identified but Norovirus was suspected based on clinical symptoms, incubation period and duration of illness. A total of 553 people were affected by AGI outbreaks, with the largest number in a single outbreak being 148 people in a Norovirus outbreak at a campsite. Three of the AGI outbreaks were associated with contamination of untreated groundwater, two were associated with treatment deficiencies (one groundwater, one surface water), and in two groundwater outbreaks problems were identified in both treatment processes and in the water distribution system. In one AGI outbreak associated with groundwater there was insufficient information to determine the cause of the contamination. The ninth AGI outbreak was associated with point of use contamination of a shared drinking water container at a gym. The single Hepatitis A outbreak occurred in an untreated groundwater supply serving a private residence and affected 16 people. Overall, slightly more than half the outbreaks associated with drinking water were attributable to deficiencies outside the jurisdiction of water utilities or at the point of use. The authors note two main trends in their discussion of drinking water-related outbreaks: • although the basis for historical comparison is limited, reported Legionella outbreaks appear to be increasing relative to outbreaks caused by other pathogens. As Legionella outbreaks are generally related to growth of the organisms in the plumbing of buildings, they are caused by factors not under
SEPTEMBER 2008
PAGE 3
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
the control of water utilities and not specifically subject to EPA regulations. • the proportion of outbreaks associated with groundwater has been increasing, most probably as a consequence of the predominant regulatory focus on improving the safety of surface water supplies. There has been a striking decline in the number of outbreaks attributable to protozoal contamination of surface water supplies since the 1980s, possibly as a result of enhanced treatment requirements in the US for such water sources. The pending implementation of the Ground Water Rule is expected to lead to improvements in the safety of many vulnerable groundwater systems. Five of the seven groundwater outbreaks attributable to lack of treatment or inadequate/interrupted treatment occurred in systems which will be subject to this new regulation from 2009. Water not Intended for Drinking (WNID) and Water of Unknown Intent (WUI) WNID is defined as water that has not been treated for human consumption in conformance with US EPA drinking water standards and is provided for uses other than drinking (for example water supplies in occupational settings, natural water bodies which may be used for drinking by campers, or irrigation waters). The definition excludes recreational water and flood water. The term WUI is used when there is insufficient information to determine whether water was treated and/or for what purpose it was supplied. Six outbreaks were reported to be associated with WNID and two with WUI during the two year surveillance period. These comprised five outbreaks of ARI caused by Legionella species (4 WNID and 1 WUI), resulting in 63 cases and seven deaths. For three of these outbreaks the mode of water exposure was via aerosols from cooling towers, the fourth outbreak was associated with a decorative fountain and the exposure source in the fifth outbreak could not be identified. Two outbreaks of Giardia intestinalis were associated with WNID. One of these was attributed to canal water being used for dishwashing and bathing in a private residence, while the second was attributed to hikers drinking inadequately treated water from a river. A WUI outbreak of E.coli O157 was linked to contaminated
HEALTH STREAM
well water intended for irrigation leaking onto a pool deck and tennis courts at a sports camp. Four previously unreported outbreaks between 1979 and 2002 are also summarised in the report. These comprised two AGI outbreaks and one Hepatitis A outbreak associated with drinking water supplies, and one outbreak of skin symptoms associated with WNID (recycled process water in a factory). Recreational Water A total of 78 waterborne disease outbreaks associated with recreational water use were reported during the two year interval. There were 58 outbreaks associated with treated recreational water facilities (swimming pools, spas, interactive fountains and kiddie pools). These comprised 35 outbreaks of acute gastrointestinal illness (AGI), 13 outbreaks of acute respiratory illness (ARI) including three with concomitant eye or ear symptoms, and 10 outbreaks of skin complaints. As in previous years Cryptosporidium was responsible for the majority of AGI outbreaks (29 outbreaks plus one mixed Cryptosporidium/Giardia outbreak). Other gastrointestinal pathogens identified in single outbreaks were Campylobacter jejuni, Giardia intestinalis, Shigella sonnei, and Norovirus. A total of 3849 people were affected by AGI outbreaks. The largest AGI outbreak was caused by Cryptosporidium contamination at an interactive fountain in a New York State park and affected 2307 people. Legionella species were responsible for eight ARI outbreaks in treated water facilities (all spa pools), one ARI outbreak was attributed to excessive chlorine gas released into pool water, three outbreaks were suspected to be linked to excessive disinfectant or disinfectant byproduct levels, and no cause was identified for the remaining ARI outbreak. A total of 208 people were affected by ARI outbreaks and there were 3 deaths (all attributed to Legionella infection). The 10 outbreaks of skin complaints affected 110 people, with Pseudomonas aeruginosa identified in four of these outbreaks and suspected in a further five, while the remaining outbreak was suspected to be caused by low pH in pool water.
SEPTEMBER 2008
PAGE 4
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
There 20 reported outbreaks for untreated recreational waters, with 19 of these outbreaks being associated with natural water bodies (lakes, rivers, marine waters). The most common type of illness was acute gastrointestinal illness (AGI), which occurred in 13 outbreaks. A range of enteric pathogens were identified in these outbreaks including E. coli O157 (3 outbreaks), Norovirus (3), Shigella sonnei (3) and Cryptosporidium (2). In two AGI outbreaks the causative agent was not identified. Two outbreaks were associated with skin symptoms and although the causative agent was not definitively identified, clinical symptoms were consistent with cercarial dermatitis. There were two outbreaks attributed to Leptospira, one to Naegleria fowleri, one outbreak of ARI associated with copper sulphate in a lake and one outbreak of mixed symptoms with unknown cause. The Naegleria fowlerii outbreak involved two fatal cases of primary amoebic meningitis (PAM) and the source of water exposure was uncertain with both cases possibly exposed to an interactive fountain at a water park and/or water in a creek. A total of 245 people were affected by disease outbreaks associated with untreated water, with the largest outbreak involving 50 cases of AGI attributed to Norovirus. Only one of the 20 outbreaks was associated with a marine water setting, with 19 occurring in freshwater settings. Under the category of single case reports associated with water exposure during 2005 and 2006, CDC received reports of 189 cases of Vibrio infection (87% from recreational water use and 13% from exposure to Hurricane Katrina flood waters), and three cases of PAM caused by Naegleria fowlerii. The Vibrio infections resulted in 18 deaths and all three cases of PAM were fatal. In addition to the outbreaks and cases occurring during the 2005-2006 period, the report also summarises details of 31 recreational water outbreaks and one case report which occurred between 1978 and 2004 but had not previously been reported to CDC. Information is also given on 32 aquatic facility-related health events occurring in New York state between 1983 and 2006 which were not
HEALTH STREAM
associated with recreational water use. The majority of these incidents involved the release of chlorine gas due to improper use of chemicals, resulting in acute respiratory symptoms in exposed persons. The authors note that the number of reported recreational water-associated outbreaks (78) in this 2year period was higher than for the previous period (62 outbreaks). This may be due to an increasing incidence of outbreaks but may also indicate improved surveillance and reporting practices. The overall findings of the surveillance program highlight a number of issues that need to be addressed to improve recreational water safety: • control of Cryptosporidium risks in treated water facilities may require additional barriers such as ozonation or UV treatment in addition to the traditional chlorine-based disinfection and filtration processes. • for untreated water bodies, management approaches include monitoring of water quality and education of swimmers to avoid high risk periods. • there is a need for better training of staff in the management of both microbial and chemical safety issues in relation to recreational water venues • regulations governing swimming pools and other water venues needs to be updated to match current knowledge of the causes of outbreaks • water users need to be made aware of the risks of faecal pollution and the need to practice good hygiene in and around recreational waters • even with the best operating practices and technology, recreational water can never be guaranteed to be free of pathogens, and water users should be made aware of this and educated to avoid swallowing water. (1) Surveillance for Waterborne Disease and Outbreaks Associated with Recreational Water Use and Other Aquatic Facility-Associated Health Events — United States, 2005–2006. Morbidity and Mortality Weekly Report, Surveillance Summaries, September 12, 2008 / Vol. 57 / No. SS-9, p 1-38. (2) Surveillance for Waterborne Disease and Outbreaks Associated with Drinking Water and Water not Intended for Drinking — United States, 2005–2006. Morbidity and Mortality Weekly Report, Surveillance Summaries, September 12, 2008 / Vol. 57 / No. SS-9, p 39-69.
SEPTEMBER 2008
PAGE 5
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
Boil Water Alerts In Queensland Boil water alerts were recently issued for several towns in far north Queensland after the detection of E. coli in water storage tanks serving the area. The affected towns are in a popular tourist area containing the Great Barrier Reef and the Daintree River and Rainforest. The alerts were issued on 5 September following positive E. coli results for seven of the twelve reservoirs supplying the towns of Port Douglas, Mowbray, Daintree Village and Rocky Point. This is a busy time for tourism operators in the area, with many people from the southern states of Australia visiting the warmer climate of Queensland during the winter, in addition to large numbers of international visitors. The area is famous for its lush tropical scenery and unspoiled beaches and reefs. There are about 11,000 permanent residents in the affected area with a similar number of tourists during peak season. The drinking water supplies for the area are managed by Cairns Regional Council, which was formed in March this year following amalgamation of Cairns City and Douglas Shire Councils. The amalgamation was part of a major reform process for local government in Queensland. The affected supplies are drawn from protected surface water sources and treated by pre-filtration (0.2 mm), membrane filtration (0.01 microns) and UV irradiation before distribution to consumers, but are not chlorinated. Many residents have opposed chlorination as they believe it would compromise the “pristine” and “chemical-free” image of the area. The Queensland Health department, however, has expressed a strong preference that a chlorine disinfectant residual should be maintained in the water supply systems. To date the community view has prevailed. According to information from the Cairns Regional Council, the monitoring program for these water supplies in the five years prior to the council merger consisted of sampling the reticulation network at various locations generally on a monthly basis. Samples were collected in the network post treatment plant and both prior to and after storage tanks, however there appear to be no records of testing water samples collected from the tanks. Following
HEALTH STREAM
the establishment of the new Council, the monitoring regime for was intensified from monthly to weekly sampling in the distribution system and more test sites were added. The first set of samples from the tanks was collected on 1 September, resulting in E. coli being detected at low levels in seven of twelve tanks. There has been a history of occasional microbiological contamination of the distribution system in the past, however samples collected over the following two days showed no evidence of E. coli contamination in the pipe network. After consultation with Queensland Health about the potential health risks, the Cairns Regional Council decided to issue the boil water alerts to consumers. Although some press reports have referred to contamination by “deadly E. coli bacteria”, there is no evidence that the E. coli detected in the water is a pathogenic type rather than a simple indicator of faecal contamination. To date there does not appear to be any evidence of a waterborne disease outbreak in the area affected by the boil water alert. Inspection of the storage tanks revealed they were in a poor state of repair and vulnerable to access by insects, birds and small animals. An emergency repair program was initiated with priority given to the tanks serving Port Douglas due to its importance a major tourism centre. Some of the tanks were able to be taken off-line for cleaning, sealing and chlorine disinfection while maintaining the water supply to customers direct from the treatment plant. However in cases where the water tanks could not be isolated, chlorination has been carried out with the tank still in service with customers notified of the chlorination procedure in advance by letter drop. According to media reports some customers and local councilors have objected to the use of chlorine even as a one-off measure in this situation. Following further microbiological testing and consultation with Queensland Health, the boil water alerts for Port Douglas and Mowbray were lifted on 10 September. The alerts for Daintree Village and Rocky Point are expected to be maintained until early October while repairs and cleaning of the remaining tanks are completed. In the longer term, a program of more substantial repairs to the storage tanks will be
SEPTEMBER 2008
PAGE 6
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
undertaken over the next year. It has been estimated this will involve costs in the order of $500,000. Cairns Regional Council has also announced it will form a Community Water Reference Group with representatives from the four districts in the area to provide advice to Council on water quality issues. The group will also include representatives from Queensland Health, the Tourist Association and the Chamber of Commerce. It is intended the group will provide a mechanism for two-way information flow between Council and the community for discussions and decision-making on water supply and water quality issues. The vulnerability of the water supplies to contamination had already been noted in a report prepared for the Water and Waste Committee of the Cairns Regional Council earlier this year. While the raw water sources are generally of high quality due to minimal human activity in the catchments, they are prone to episodes of high turbidity triggered by rain events. It is considered that the current filtration and UV treatment plants are adequate to ensure the safety of treated water even during such events, however the lack of a chlorine residual in the distribution system means there is no disinfectant barrier against ingress of contamination. In these circumstances it is essential that the physical integrity of the distribution system is rigorously maintained to ensure the safety of the water supplied to consumers. The available information on this incident suggests that contamination of the water storage tanks is not a new event (given their poor state of repair), but merely that the intensified water quality monitoring program undertaken by the new Council has allowed detection of the problem. Nevertheless the Council and Queensland Health had an obligation to warn consumers of the potential health risks of the situation. While the presence of E. coli bacteria does not necessarily mean that faecal pathogens are present, the possibility cannot be ruled out. There are a number of instances in the literature where waterborne outbreaks have resulted from birds and small animals introducing contamination into water storage tanks.
UK NDMA Survey The UK Drinking water inspectorate has released a report on a survey of N-nitrosodimethylamine (NDMA) in water supplies from selected treatment plants in England and Wales. The survey targeted locations which had characteristics reported to favour NDMA formation including: • raw water source (e.g. groundwater, lowland surface water, upland surface water) and quality (e.g. presence of organics, ammonia, nitrite); • proximity of sewage effluent or agricultural/industrial inputs; • use of treatment chemicals (e.g. polyDADMAC or Epi-DMA polyelectrolytes); • use of treatment processes (e.g. ion exchange, GAC adsorption, chloramination); and • distribution characteristics. Based on the presence of one or more of these factors, 41 treatment plants from 11 water utilities were selected. In addition, two treatment plants which had none of the known characteristics predisposing to NDMA formation were included as controls. NMDA was assayed in raw water, samples taken at various points in the treatment process, finished water at the plant and from the distribution system. Sampling was conducted on a quarterly basis with each plant being sampled between one and four times. A fifth survey and a set of laboratory experiments were subsequently carried out to investigate some of the results from the first four surveys. NDMA was found at low concentrations (up to 5.8 ng/L) in finished water from three treatment plants. This is substantially below the guideline value of 100 ng/L established by the World Health Organisation, and lower than the concentrations from a number of other surveys internationally. Unexpectedly, the key factor associated with detection of NDMA appeared to be the use of ferric coagulants. This was confirmed by laboratory experiments with distilled or deionised water dosed with coagulant from one of the treatment plants. The results indicate that NDMA may be present at low levels in ferric sulphate coagulants used in the UK water industry but probably not in ferric chloride. http://www.dwi.gov.uk/ Information Letter 09/2008
HEALTH STREAM
SEPTEMBER 2008
PAGE 7
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
Lead In NSW School Rainwater Tanks
News Items
Lead contamination in rainwater tanks serving NSW regional schools has been in the spotlight recently after a newspaper obtained a Department of Education report under Freedom of Information laws. The report detailed a survey of water quality in school rainwater supplies carried out last year in consultation with the NSW Health department. According to the media reports 330 school supplies were tested, with 36 of these returning lead results above the Australian Drinking Water Guideline of 10 microgram/L. In response to the publicity, the NSW Department of Education and Training issued a media release stating that schools had been advised of the problem when the test results were obtained and requested to stop using the rainwater tanks for drinking purposes. NSW Health advised that the levels of exposure were not sufficient to warrant testing blood lead levels in school children. Pregnant women, infants and children under 5 years of age are most sensitive to the toxic effects of lead on the nervous system. The ADWG guideline value has been set to protect these most vulnerable groups, and older children are less susceptible to adverse effects. The guideline setting process also assumes that all water being consumed is from the lead-contaminated source, whereas in this situation, children would consume only a portion of their water intake at school, and only during the school year.
Drinking Water Treatability Database The US EPA has launched a web database containing information on drinking water contaminants and treatment options for their removal. The database provides an overview of each contaminant, a summary of its properties, information on fate and transport, and the effectiveness of treatment processes. The information has been compiled from peer-reviewed journals and conferences, other conferences and symposia, research reports, theses and dissertations, and is fully referenced. At present only 10 contaminants are listed but it is intended to expand the database to include over 200 microbial, chemical and radiological contaminants. The database information can be searched by contaminant or by treatment process. http://iaspub.epa.gov/tdb/pages/general/home.do
An aspect of the rainwater quality survey not mentioned in the media reports is the more widespread problem of sporadic microbial contamination of water in rainwater tanks. This is seen as a more significant problem, with a higher risk of adverse health effects. The Department of Education and Training is working in consultation with the Health Department to improve both chemical and microbial water quality of drinking water at regional schools. The improvement program includes connection of schools to town water supplies where this is feasible, installation of UV disinfection systems, and a pilot project using filters to remove lead. As an interim measure some schools are being supplied with bottled water for drinking while the feasibility and cost of longer term solutions are assessed.
HEALTH STREAM
Canadian Fluoride Review A review by an expert panel for Health Canada has found no basis for changing current water fluoridation policies. The panel reviewed the evidence on risks and benefits and concluded the weight of evidence did not support any adverse health effects other than dental fluorosis. Rates of dental fluorosis in Canada were found to be acceptably low, and have probably declined in the last decade. http://www.hc-sc.gc.ca/ewh-semt/pubs/watereau/2008-fluoride-fluorure/index-eng.php NSW Private Water Supply Guidelines The NSW Department of Health recently issued new guidelines for private water supplies which serve the public. The guidelines cover surface water, groundwater and water from rainwater tanks that is supplied for drinking at facilities such as caravan parks and camp grounds, guest houses, petrol stations and roadhouses and sports facilities. The guidelines provide information on protection and management of water supplies, water treatment and disinfection, monitoring requirements, and legal responsibilities to ensure provision of safe water to the public. http://www.health.nsw.gov.au/resources/publichealth /environment/water/pwsg_pdf.asp
SEPTEMBER 2008
PAGE 8
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
From the Literature
Arsenic
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:
Arsenic exposure and prevalence of type 2 diabetes in US adults. Navas-Acien, A., Silbergeld, E.K., Pastor-Barriuso, R. and Guallar, E. (2008) JAMA, 300(7); 814-22.
www.waterquality.crc.org.au/pubs Predicted intake of trace elements and minerals via household drinking water by 6-year-old children from Krakow, Poland. Part 3: Aluminium. Barton H. (2008) Food Additives and Contaminants, 25(5); 588-603. Arsenic in drinking water and lung cancer: A systematic review. Celik I, Gallicchio L., Boyd K., et al. (2008) Environmental Research 108(1); 48-55. Molecular assessment of bacterial pathogens - a contribution to drinking water safety Brettar, I. and Hofle, M.G. (2008) Current Opinion in Biotechnology, 19(3); 274-280. Selected markers of cardiovascular disease in a population exposed to arsenic from drinking water. BosĚŒnjak Z, Cavar S, Klapec T et al. (2008) Environmental toxicology and pharmacology, 26(2); 181-186. A synopsis of research needs identified at the Interagency, International Symposium on Cyanobacterial Harmful Algal Blooms (ISOC-HAB). Hudnell HK and Dortch Q. (2008) Advances in Experimental Medicine and Biology, 619;17-43. (Monograph series) Drinking water disinfection by-product exposure and duration of gestation. Hoffman CS, Mendola P, Savitz DA, et al. (2008) Epidemiology, 19(5); 738-746. Use of surface water in drinking water production associated with municipal Legionnaires' disease incidence. Den Boer JW, Coutinho RA, et al. (2008) Journal of Epidemiology and Community Health, 62(4); Drinking water security and public health disease outbreak surveillance. Babin SM (2008) Johns Hopkins APL Technical Digest, 27(4); 403-411. Assessment and management of the first German case of a contamination with perfluorinated compounds (PFC) in the Region Sauerland, North Rhine-Westphalia. Wilhelm M, Kraft M et al.(2008) Journal of Toxicology & Environmental Health Part A, 71(11-12); 725-33. Presence of Cryptosporidium spp. and Giardia duodenalis through drinking water. Castro-Hermid JA, Garcia-Presedo I, et al. Science of the Total Environment, doi:10.1016/j.scitotenv.2008.06.040 Assessment of microbiological quality of drinking water from household tanks in Bermuda Levesque B, Pereg D, Watkinson E, et al. (2008) Canadian Journal of Microbiology, 54(6); 495-500. Water contamination events in UK drinking-water supply systems. Gray, J. (2008) Journal of Water and Health, 6(SUPPL. 1); 21-26. The role of birds in dissemination of human waterborne enteropathogens Graczyk, T.K., Majewska, A.C. and Schwab, K.J. (2008) Trends in Parasitology, 24(2); 55-59.
HEALTH STREAM
Inorganic arsenic has been found to be highly toxic and carcinogenic for humans. Exposure to high levels of inorganic arsenic has also been found to increase glucose and insulin levels in animal models, decrease glucose uptake in insulin-sensitive cells and interfere with transcription factors involved in insulin signal transduction and insulin sensitivity in vitro. Some epidemiological studies have found high chronic exposure to inorganic arsenic in drinking water (greater than 100 micro g/L) to be associated with diabetes. This study investigated the association of urine arsenic with type 2 diabetes and with the levels of glycated haemoglobin in adults. Data from 788 participants in the 2003-2004 National Health and Nutrition Examination Survey (NHAMES) conducted in the United States was used in this study. Spot urine samples were obtained at the time as physical examinations. Total arsenic and arsenic species (arsenite, arsenate, methylarsonate, dimethylarsinate and arsenobetaine) in urine were measured. Inorganic arsenic compounds (arsenite and arsenate) are metabolised to methylarsonate and dimethylarsinate and excreted in the urine together with unchanged inorganic arsenic. Arsenobetaine is an organic arsenic compound and is excreted unchanged in the urine and is considered non-toxic. In most participants, the levels of arsenite, arsenate and methylarsonate in urine were below the analytical detection limits so these compounds were not included in the analysis. There were 93 participants with diabetes (73 with a prior diagnosis). Questionnaire details obtained included sex, age, race and ethnicity; education, smoking and alcohol consumption status; and dietary recall interviews for the past 24 hours. Body mass index was calculated. Serum cotinine was measured as well as blood mercury levels. Urine creatinine was measured to account for urine dilution in spot urine samples. Linear and logistic regression models for total urine arsenic concentrations and diabetes end points were fitted with increasing degrees of adjustment.
SEPTEMBER 2008
PAGE 9
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
The median urine levels in the study population were 7.1 micro g/L for total arsenic, 3.0 micro g/L for dimethylarsinate and 0.9 micro g/L for arsenobetaine. There were significant differences between different races in the levels of total arsenic and dimethylarsinate, with levels being higher in black, Mexican-American and “other� races than among whites. No significant differences between races were seen for arsenobetaine levels. Models were adjusted for sociodemographic and diabetes risk factors, and participants with type 2 diabetes had similar levels of total arsenic and dimethylarsinate and lower levels of arsenobetaine compared with participants without type 2 diabetes. Following adjustment for urine arsenobetaine and blood mercury which are biomarkers of seafood intake, participants with type 2 diabetes had 26% higher total arsenic levels (95% CI, 2.0%-56.0%), nonsignificant 10% higher dimethylarsinate levels (95% CI, -8.0% to 33.0%), and similar arsenobetaine levels than participants without type 2 diabetes. The odds ratios (ORs) for diabetes comparing participants in the 80th vs the 20th percentiles after similar adjustments were 3.58 (95% CI, 1.18-10.83) for the level of total arsenic, 1.57 (95% CI, 0.89-2.76) for dimethylarsinate and 0.69 (95% CI, 0.33-1.48) for arsenobetaine. Total urine arsenic and dimethylarsinate levels but not arsenobetaine, were also positively associated with increasing levels of glycated haemoglobin after adjustment for markers of seafood intake however associations were not statistically significant. This study demonstrated that increasing levels of total urine arsenic were positively associated with type 2 diabetes prevalence and with levels of glycated haemoglobin after adjustment for diabetes risk factors and markers of seafood intake. Exposure to inorganic arsenic in this representative sample of the US population is believed to be mostly attributable to drinking water. Exposure to organic arsenicals was not found to be associated with the risk of diabetes. Prospective studies are required in populations exposed to a range of inorganic arsenic levels to establish whether this association is causal. Other possible explanations that presently cannot be ruled out are that diabetes affects the metabolism of arsenic, or that the apparent association reflects
HEALTH STREAM
residual confounding by geographical area or urbanisation. However, as there is extensive exposure to inorganic arsenic from drinking water worldwide, it is important from a public health perspective to confirm the role of arsenic in diabetes development. Comment This study could not provide evidence of causation as the exposure (inferred from arsenic in the urine) was measured at the same time as the proposed effect (diabetes or pre-diabetes marker). Prospective studies of people without diabetes at enrolment and with subsequent exposure to differing levels of arsenic in drinking water would be needed to support a causal relationship. Disinfection Byproducts Drinking water disinfection by-product exposure and fetal growth. Hoffman, C.S., Mendola, P., Savitz, D.A., Herring, A.H., Loomis, D., Hartmann, K.E., Singer, P.C., Weinberg, H.S. and Olshan, A.F. (2008) Epidemiology, 19(5); 729-737. Some previous studies have suggested that exposure to disinfection by-products (DBPs) during pregnancy may increase the risk of adverse pregnancy outcomes. Some studies have reported a moderately increased risk of delivering small-for-gestation-age (SGA) infants among women exposed to high levels of total trihalomethanes (TTHMs), with relative risks ranging up to 1.5. TTHMs have also been associated with decreased mean birth weight and an increased risk of delivering a low birth weight infant in some studies. This study was undertaken to examine the association between DBP measures and foetal growth using improved exposure data that allow interindividual variability to be estimated more accurately than in previous studies. Women were recruited at less than or equal to 12 weeks gestation from three study sites in the United States. One site had moderate levels of chlorinated DBPS (chlorinated DBP site), one site had moderate levels of brominated DBPS (brominated DBPS site), and one site had low levels of all DBPS (low DBP site). The analysis included 1854 live births born at 37 weeks gestation or later. Information was obtained
SEPTEMBER 2008
PAGE 10
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
on infant date of birth, birth weight and sex from medical records or vital records and from participant self-report. SGA was defined as an infant with a birth weight below the tenth percentile for his or her gestational age at birth, sex, maternal race/ethnicity and parity. Gestational age at birth was calculated from first trimester report of last menstrual period (LMP) which was corrected by ultrasound if the two estimates differed by more than seven days. Water samples were collected from a single, representative location in the water distribution system on a weekly basis at the study sites with moderate DBP levels and biweekly at the low exposure site. Concentrations of the 4 individual TTHM species, 9 haloacetic acid species, and total organic halide were measured. The sum of the 3 TTHMs was calculated as well as the sum of 5 haloacetic acids (HAA5) and the sum of all 9 haloacetic acids. There were two exposure metrics examined: (1) estimated residential (tap water) concentrations in the water distribution system serving a woman’s residence, and (2) estimated personal exposure. Personal TTHM and HAA5 exposures were estimated by combining residential concentrations with detailed information on tap water exposure collected during telephone interviews at baseline (by 16 weeks gestation) and follow-up (between 20 and 25 weeks gestation). Associations between aggregate DBP measures (TTHM, HAA5 and total organic halides) and the probability of delivering a SGA infant were examined using log binomial regression. Associations with term birth weight were examined using linear regression. A Bayesian analysis was conducted to examine associations between individual DBP species and foetal growth. The proportion of SGA infants was higher at the brominated DBP site (8.2%) than at the chlorinated site (4.8%) and the low DBP site (5.9%). Mean birth weight among term births was higher at the chlorinated site than at the brominated and low DBP sites (although statistical significance is not stated). TTHM concentrations were similar between the chlorinated and brominated DBP sites, however the chlorinated site had slightly higher concentrations of HAA5 and slightly lower concentrations of total
HEALTH STREAM
organic halide compared with the brominated DBP site. The brominated DBP sites had much higher concentrations of bromine-containing DBP species and much lower concentrations of nonbrominecontaining species compared with the chlorinated DBP site. When comparing quartiles of moderate DBP exposure with the low exposure group, overall there was no consistent patterns of association with increasing TTHM, HAA5 or total organic halide residential levels or increasing personal TTHM or HAA5 exposure during the third trimester and SGA The highest quartile of personal TTHM exposure was consistently associated with increased risk across all 3 trimesters but associations were attenuated for first and second-trimester exposure compared with the third trimester. When women were divided into two exposure groups for third-trimester residential TTHM concentration using the current US regulatory limit 80 microg/L as the cut-off value, those above the regulatory limit had twice the probability of delivering an SGA infant (RR 2.0, 95% CI 1.1-3.6) compared to those below the limit. However the number of women exposed above the regulatory limit was small and the effect estimates were unstable. There was no dose-response suggested for birth weight in relation to TTHM, HAA5 or total organic halide for residential or personal exposure estimates. At both the chlorinated and brominated sites, chloroform was associated with increased risk of delivering an SGA infant according to Bayesian analysis. However, Bayesian 95% credible intervals for all effect estimates included the null value, indicating that no effect of DBPs was within the probable range. No effect of chloroform on term birth weight was found and an effect of chloroform with SGA was not indicated from results of the maximum likelihood analysis at the chlorinated site where levels of chlorinated DBPs, number of participant and the overall strength of the data was greater. When personal exposure to individual DBPs species was examined findings were similar using maximum likelihood and sensitivity analyses. This study does not suggest an adverse effect of TTHM or HAA5 exposure on foetal growth at
SEPTEMBER 2008
PAGE 11
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
residential concentrations below the current US regulatory standards. An association of TTHM with SGA was only found for average residential concentrations greater than or equal to 80 micro g/L, however few women experienced TTHM exposure levels this high in the study. Also, none of the individual TTHM or haloacetic acid species were consistently associated with foetal growth restriction. Fluoride Research on the intellectual development of children in high fluoride areas. Chen, Y., Han, F., Zhou, Z., Zhang, H., Jiao, X., Zhang, S., Huang, M., Chang, T. and Dong, Y. (2008) Fluoride, 41(2); 120-124. Fluoride is able to pass through the placental barrier and concerns have been raised that it may accumulate in foetal brain tissue and influence intellectual development after birth. However studies on this topic have had inconsistent results. This paper describes a study of 7-14 year old children living in an endemic fluorosis village in China compared with children living in a control village with low fluoride levels in drinking water. The high fluoride village was Biji, Linyi County, Shanxi Province where drinking water has high concentrations of fluoride (4.55 mg/L). There is a rate of dental fluorosis of 85% and a rate of skeletal fluorosis of 25% in this community. The village of Jiaobei in the same county was used as a control. In this village the fluoride concentration in drinking water is 0.89 mg/L with a rate of dental fluorosis of 15% and no cases of skeletal fluorosis. The two villages were essentially the same in relation to occupations, cultural level, standard of living, lifestyle habits, access to health and transportation facilities etc.
The average IQ of the 320 children tested from the Biji village was 100.24 +/- 14.52. The average IQ of the 320 children tested from Jiaobei village was 104.03 +/- 14.96. This result was very significant with the high fluoride area having lower average IQ than the control area (t = 3.24, P less than 0.01). In the high fluoride area, children in the excellent or outstanding IQ range made up 9% of all children tested compared to 15% in the control area. In the high fluoride area children in the 80-90 IQ range and below make up more than 25% of the total whereas in the control area only 18% of children fall into this range. The IQ of children in both areas was also correlated with the occupation and educational levels of their parents. The IQs of children born into “employed” households was higher than those born into farming households and the IQ of children increased along with the education level of their parents. These results were also statistically significant and were of a similar magnitude to the IQ differences associated with fluoride exposure. The results clearly show that there is a significant difference between the intellectual ability of 7-14 year old children in the high fluoride endemic area compared with the non-endemic control area with the average IQ of children in the high fluoride area significantly lower. The associations seen between IQ and parental occupation and education level also illustrate the need to carefully match comparison populations for other factors that may influence intellectual development. Comment The “control” group in this study was exposed to drinking water containing 0.89 mg/L, which is close to the recommended level of 1.0 m/L for drinking water fluoridation. Legionella
There were 40 children from each age group randomly selected to be subjects (7 to 14 years in 1 year increments = 8 groups or 320 children per village), with equal numbers of boys and girls. For the child to be eligible, the mother must have resided in the village for the duration of pregnancy. The intellectual ability of the children was tested using the rural version of the Chinese Standardised Raven Test.
HEALTH STREAM
Occurrence of Legionella in hot water systems of single-family residences in suburbs of two German cities with special reference to solar and district heating. Mathys, W. (2008) International Journal of Hygiene and Environmental Health, 211(1-2); 179-185.
SEPTEMBER 2008
PAGE 12
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
Legionella are found in surface and ground waters as part of the natural microbial flora. Man-made hot water systems can facilitate Legionella growth from very low natural concentrations to markedly higher concentrations when water temperatures are below 55 degrees C. The most common source of nosocomial and community acquired legionellosis worldwide is hot potable water (30-55 degrees C) that is dispersed by shower-heads, faucets etc. There have been numerous reports of colonisation of warm water systems in hospitals, nursing homes and large apartment building whose complex structure is believed to provide ideal conditions for the growth of the bacteria. There is little known however, especially in Germany, about the growth of Legionella in small residential units, where the volume of stored water is either relatively small or absent as it the case of instantaneous point-of-use water heaters. This study investigated the extent to which Legionella contamination in hot water systems supplying only a single family is a potential sources of community acquired legionellosis and evaluated factors promoting the growth of the bacterium in these small hot water systems. The study area included the city suburbs of Munster and Bielefeld in North-Rhine-Westphalia, Germany. There were 452 single family houses randomly selected for the study. All of the houses were supplied by treated ground water compliant with German drinking water regulations and was nonchlorinated when delivered. Water sampling took place from April 2000 to February 2003. Samples were mostly collected from a faucet in the bathroom. Faucets were flamed with a gas burner and the first 5 litres of hot water was discarded before collecting the sample. The temperature of the sampled water was measured using an electronic thermometer. Samples were analysed for copper and Legionella. A standardised questionnaire was used to evaluate risk factors possibly associated with colonization including: age of building, type of hot water preparation, volume of storage tank, material used in the construction of the plumbing systems and mode of operation. No Legionella-positive water samples were found in houses using point-of-use, instantaneous water
HEALTH STREAM
heaters (n=52). The mean hot water temperature in these houses (54.9 degrees C) was considerably higher than in households using hot-water storage tanks (50.6 degrees C). Legionella was found in 12% of hot water systems of households which used a storage tank and recirculation (n=400). This rate of colonisation is considerably less than in large building hot water systems however the maximum bacterial counts in the small hot water systems ranged up to 100,000 CFU/100 ml which is comparable to heavily colonised hot water systems in large buildings. Nearly all of the positive specimens were identified as L. pneumophila (93.9%), 71.8% of which belonged to serogroup 1. Water systems with copper pipes were colonised significantly more often than those with galvanised steel or plastic pipes even though the temperature of the hot water in these systems was similar. Hot water systems containing greater than 0.5 mg Cu/l were more frequently colonised and had a higher mean Legionella counts that those with copper concentrations of 0.5 mg/l or less. The volume of the storage tanks did not seems to be an important factor for growth of Legionella. Hot water systems in houses with plumbing less than two years old were not colonised even though warm water temperatures did not differ from those in older systems. There was no significant effect on Legionella counts of interrupting the hot water circulation for some hours at night, nor raising the temperature of the whole hot water system on a regular basis to 60 degrees C. Raising hot water temperatures to 60 degrees periodically and for very short time intervals seemed to favour growth of Legionella instead. The type of hot water production strongly influenced Legionella contamination. More than 50% of houses that heated water using heat exchanges supplied by district heating systems (heating of water at a central facility with subsequent distribution to individual dwellings) had the bacterium isolated compared with only 5.5% of houses that heated water using conventional hot water systems. Mean hot water temperatures in district heating systems were significantly lower (47.9 degrees C vs 50.7 degrees C) than in other systems. Contrary to expectations, there was no evidence found of increased
SEPTEMBER 2008
PAGE 13
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
colonisation when solar energy (dual storage tanks) was used even though the hot water produced is 3 degrees C lower than in the other systems. Instead, colonisation rates were lower in systems using solar energy. The factors responsible for Legionella colonisation in hot water systems of large buildings have been found to also exist in smaller residential systems. There is a strong correlation between the temperature of the hot water and Legionella counts, with maximum growth at temperatures between 30 and 46 degrees C, while above 55 degrees proliferation is inhibited. Low temperatures favour growth of Legionella in both large and small hot water systems and when Legionella counts are very high there is a risk for elderly and immunocompromised members of the community. Private residences are an important source of community-acquired legionellosis and those at risk of acquiring Legionnaires’ disease would definitely benefit from preventive measures which reduce the proliferation of Legionella in hot water systems or which remove the bacteria at the point-of-use such as filtration devices. Nitrate Nitrate contamination in groundwater on an urbanized dairy farm. Showers, W.J., Genna, B., McDade, T., Bolich, R. and Fountain, J.C. (2008) Environmental Science and Technology, 42(13); 4683-4688. This study used analysis of isotopic composition to examine the origins of nitrate contamination in groundwater on a new housing development built on a former dairy farm area in North Carolina USA. Dairy farms operated on the site from the 1950s until 1986, and houses were built from 1993 onwards. The development is in a “critical watershed area� that provides drinking water for population centres downstream, so housing developments are not permitted to use municipal water and sewer networks, instead being served by individual wells and septic tank systems. These private drinking water supplies are not subject to drinking water regulations. From June 2003 to June 2007, one-litre water samples were collected from 50 drinking water wells.
HEALTH STREAM
In spring 2004, nine shallow Geoprobe monitoring wells were installed to sample shallow groundwater near a lagoon which was drained and buried in 1995 and in the septic leach field in the central area of the site where the highest drinking water nitrate levels were found. Nutrient and ion concentrations in water samples (NO3, NH4, PO4, Cl, Br) were determined. To determine the source of nitrate contamination in drinking water wells, the isotopic composition of nitrate, ammonium, groundwater molecules and chloride/bromide ratios were analysed. In 44% (22 of 50) of the domestic wells and in 56% (5 of 9) of the shallow wells, nitrate concentrations were higher than the Maximum Contaminant Limit for drinking water of 10 mg/L No3-N. The potential sources of nitrate contamination at this site include lawn fertilisers, organic matter in the buried dairy waste lagoon, animal wastes leached from the dairy pastures and effluent from septic systems. The results of the isotopic analysis indicated that nitrate contamination in the drinking water wells came predominantly from animal waste leached from pasture land into the groundwater over 35 years of dairying operations, rather than the other potential sources. There is an increasing trend for urban development on former farmlands in the US as populations increase, and most of the current construction regulations do not consider the problem of preexisting groundwater contamination. The authors suggest that groundwater quality testing regulations for newly constructed wells are needed in order to protect public health in these situations. Organic Wastewater Contaminants A national reconnaissance for pharmaceuticals and other organic wastewater contaminants in the United States - II) Untreated drinking water sources. Focazio, M.J., Kolpin, D.W., Barnes, K.K., Furlong, E.T., Meyer, M.T., Zaugg, S.D., Barber, L.B. and Thurman, M.E. (2008) Science of the Total Environment, 402(2-3); 201-216.
SEPTEMBER 2008
PAGE 14
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
This paper summarises a national-scale reconnaissance of 100 organic wastewater contaminants (OWCs) undertaken in 74 raw, untreated sources of drinking water from targeted surface and ground water across the United States. Classes of substances tested included veterinary and human antibiotics, prescription and non-prescription drugs, biogenic steroids and a range of other chemicals reportedly found in sewage (including fragrances, insecticides, herbicides, industrial chemicals, preservatives).
groups of chemicals that had individual chemical maximum concentrations exceeding 2 microg/L (biogenic steroids, detergent metabolites, solvents) and seven groups (including antibiotics, nonprescription drugs, and other prescription drugs) which had a maximum concentration less than 0.5 microg/L. There was a statistically significant difference of detection frequencies and total concentrations of all compounds between surface water and ground water sites (Wilcoxon rank-sum test; p=0.0015 and p=0.001 respectively).
Sites were chosen in areas that were known or suspected to have at least some human and/or animal wastewater sources in upstream or upgradient areas. Water samples were collected from raw, untreated ground and surface water sources of drinking water in the summer of 2001. Twenty-five ground water and 49 surface water sources for public drinking water systems were selected from 25 states and Puerto Rico with populations served ranging from one family to 8 million people.
This study provides new baseline knowledge on a wide variety of OWCs in a variety of ground and surface water sources across the United States. This knowledge will help to prioritise and determine the need (if any) for future occurrence, fate and transport and health-effects research for subsets of OWCs most likely to be found in water resources used for drinking water in the United States.
Out of the 100 OWCs analysed, 63 were detected at least once in raw water samples. The maximum number of compounds detected at any one site was 31 and the median number of detections was four per site. At six sites, none of the tested compounds were detected. The most frequently detected compounds included: cholesterol (41.9%, biogenic steroid), metolachlor (39.3%, agricultural herbicide), cotinine (35.1%, nicotine degradate), and prometon (25.7%, non-agricultural herbicide). In the subcategory of pharmaceuticals (including prescription drugs and antibiotics) 60% of the tested compounds were not detected in any water sample. The concentrations of all the detected compounds were normally in the submicrog/L range with some maximum concentrations above a few microg/L. The OWCs with the highest maximum concentrations measured were not necessarily among the most frequently detected compounds.
Contamination of potable water distribution systems by multiantimicrobial-resistant enterohemorrhagic Escherichia coli. Ram, S. (2008) Environmental health perspectives, 116(4); 448-452.
Non-prescription drugs (including caffeine and its metabolite 1,7 dimethylxanthine, cotinine, ibuprofen and acetaminophen) were detected more frequently than any other group in surface water samples other than naturally occurring steroids. There were three
HEALTH STREAM
Pathogenic E. coli
Escherichia coli is a normal inhabitant of the gastrointestinal tract of warm-blooded animals and is used as an indicator of water quality. Certain pathogenic serotypes have been associated with waterborne disease outbreaks and mortality in humans. Enterohemorrhagic E. coli (EHEC) causes disease in humans through production of one or more shiga-like toxins (encoded by stx1 and stx2 genes) which inhibits protein synthesis of host cells, leading to cell death. EHEC is harboured mainly in cattle but also by a wide range of animals and birds. In humans, ingestion of a few as 1-10 EHEC cells may cause illness, and this organism has caused a number of drinking water disease outbreaks. In India there is a high incidence of waterborne disease however the potable water supply has never been investigated for the presence of specific pathotypes of diarrheagenic E. coli including EHEC. This article reports on the occurrence of E.coli carrying virulence determinants
SEPTEMBER 2008
PAGE 15
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
in samples collected from the drinking water distribution system of northern India and their sensitivity to antimicrobials. Water samples were collected on the same day at six sites along the water distribution system in Lucknow, a major city in northern India. E. coli from water samples was isolated by membrane-filtration technique and identified by biochemical characterisation. E. coli isolates were screened for virulence genes using polymerase chain reaction (PCR). In addition to the two stx genes, the isolates were also tested for eaeA , hlyA and chuA which also play a role in the virulence of EHEC strains. The isolates positive for virulence determinants were screened for susceptibility to 15 antimicrobials from six different classes by the disk diffusion method. The drinking water distribution system was contaminated by E. coli except at site 4 (waterdistribution pipeline that neither percolated nor ran along open drainage) and at site 1 (Aishbagh Waterworks) where the total coliform and faecal coliform count was zero. The other four sites all had E. coli detected, probably due to contamination entering the distribution system via rusted pipes. Fifteen randomly selected isolates from each of the four sites were tested for virulence determinants. Eighteen of the 60 coli isolates screened were positive for at least one virulence determinant. The virulence genes present were both stx1 and stx2 for 33.3% of the 18 isolates, stx2 for 55.6% and stx1 for 11.1% of isolates. The chuA and hlyA genes were present in 16.7% and 23.3% of isolates, respectively. The eaeA gene was present in all of the isolates. All of the potential EHECs were found to be resistant to at least one antimicrobial agent. There were 33.3% of isolates resistant to tetracycline and 27.7% resistant to the beta-lactam class of antimicrobials. There were 61.1, 38.9 and 11.1% of isolates which possessed reduced susceptibility (intermediates) to neomycin, streptomycin and piperacillin, which may indicate possible development of resistant strains in the future. The results of this study highlight the human health risk associated with exposure to contaminated drinking water. The E. coli detected were in a culturable metabolic state which may be explained by
HEALTH STREAM
recent contamination of the water distribution system by human and/or animal faeces due to defective sewage lines and storage tanks. The presence of the eaeA gene in all of the isolates positive for virulence makes these isolates more virulent because this gene is required for expression of the full virulence of shiga toxin-producing E. coli (STEC) in humans, leading to hemorrhagic colitis and haemolytic uremic syndrome. The emergence of resistance and decreasing levels of susceptibility (intermediates) of E. coli to a wide spectrum of antimicrobials found it this study is of concern as it may limit the availability of antimicrobials for clinical management of waterborne outbreaks in future. Comment It should be noted that treatment of EHEC infections with antibiotics is not recommended as there is some evidence this may increase the risk of developing haemolytic uremic syndrome (a severe and potentially fatal complication). The antibiotic susceptibility of the organism therefore may not be relevant to the clinical outcome of infection. The authors note that widespread use of ineffective doses of antibiotics in developing countries is probably responsible for the high rate of resistant bacteria in faecally contaminated water. Petroleum Human health risks of petroleum-contaminated groundwater. Lopez, E., Schuhmacher, M. and Domingo, J.L. (2008) Environmental Science & Pollution Research, 15(3); 278-88. Petroleum is a naturally occurring liquid with a varying composition and complexity. Petroleum products commonly contain the volatile organic compounds Benzene, Toluene, Ethylbenzene and Xylene (BTEX) which at high levels can pose a risk to human health. The main routes of soil and groundwater contamination include industrial activities, leaking storage tanks and accidental spills. The aim of this study was to estimate indoor exposure through the use of contaminated tap water and the human health risks from this exposure. The investigation focused on a case study of tap water contaminated with BTEX. The case study considers
SEPTEMBER 2008
PAGE 16
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
an industrial oil spill due to an accident in a storage tank containing industrial oil (88% inert oil and 12% BTEX). It was assumed the resulting oil infiltration was around 1 cubic metre at 1 metre depth, and a drinking well was located at 75 m from the source at 6 m depth. The area impacted was assumed to be a residential industrial site without gardens or playgrounds and therefore the potentially contaminated water is only used for household purposes. A multiphase and multicompartment model was used to evaluate the health risks for the exposed population living in the vicinity of the industrial area due to the use of potentially contaminated tap water. The movement of the chemicals through the soil to the well was modelled, followed by modelling of human exposure considering a combination of the three exposure pathways: inhalation, direct ingestion and dermal absorption. Models were developed to evaluate indoor exposure via each of these pathways. The risk for adverse human health effects was estimated using different equations depending on whether the chemicals are potential carcinogens or non-carcinogens. For the purposed of risk evaluation the exposed population was divided into two groups (adults and children) considering different physical conditions (breathing rate, body surface area, etc.). The Monte Carlo simulation was used to deal with the uncertainty and variability of the parameters included in the model. The concentrations of BTEX in a drinking well were simulated as a function over time to calculate the exposure due to the use of water from this contaminated drinking well. BTEX concentrations were predicted to fall to nearly zero at 1000 days so this period was considered for exposure evaluation. BTEX exposure by different pathways for adults and children was calculated with mean values and the percentiles 10%, 50% and 90% determined. The noncarcinogenic risk associated with BTEX exposure for adults and children was calculated. The results showed that there is no risk through the consumption and use of BTEX-contaminated water for either adults or children living in the neighbourhood of the petroleum spill. The carcinogenic risk for benzene (the only BTEX component considered to be
HEALTH STREAM
potentially carcinogenic) for adults and children was also calculated. The results showed that the total risk is lower than the assumable risk (1 x 10-6) for Benzene. For adults, the highest contribution to the carcinogenic risk was due to oral exposure (93%) followed by inhalation (7%). For children, the contribution to total risk was 66% for oral ingestion of tap water, 34% for inhalation and nearly null for dermal absorption. A sensitivity analysis was conducted for adults and children to rank the importance of the influential factors for human exposure. In adults, direct ingestion was the most significant factor (around 85%) followed by body weight (approx. 12%) and time of shower (approx. 2%). The remaining variables only accounted for less than 1% of the variability. In children, the most significant variable was also direct ingestion (45%), followed by time of the shower (approx. 15%), volume of the shower room (11%) and body weight (10%). The remaining variables only accounted for less than 1% of the variability. The maximum concentrations in tap water of the contaminants in this model were below the US EPA Maximum Contaminated Level (MCL) in drinking water and therefore the population living in the neighbourhood would be able to drink this water without health risks. No remediation measures in the area of the spill would have been necessary. The model used here can serve as a useful tool for predicting indoor exposure to substances for which no direct data are available. The model reduces monitoring efforts and observes how different processes affect outcomes. The main advantages of using model approaches are that they can be generally simple, quick and inexpensive and they can be used as a screening tool for assessing the health risk of chemicals. The information gathered from using models can help to support decision associated with the treatment of polluted areas on which little information is available. Comment The term “assumable risk” in this paper corresponds to the “tolerable risk” of cancer from lifetime exposure to a chemical contaminant. The US
SEPTEMBER 2008
PAGE 17
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
EPA generally uses 1 in a million as the tolerable risk level while WHO uses 1 in 100,000. Plastic Pipes Are there health risks from the migration of chemical substances from plastic pipes into drinking water? A review. Stern, B.R. and Lagos, G. (2008) Human and Ecological Risk Assessment, 14(4); 753-779. The use of synthetic plastic pipes for potable water has increased during the past two decades due to a combination of corrosion resistance and low cost. The base resin of such pipes is derived from fossil fuels and a variety of additives are incorporated during manufacturing to enhance material durability, impact strength and toughness, and to resist degradation during processing and under field-use conditions. This review evaluates the literature on the occurrence of regulated and unregulated substances in drinking water related to the use of plastic pipes, characterises potential health hazards and describes uncertainties associated with human health and exposure which require further research. Numerous chemical substances in polymeric tubing have the potential to migrate from the pipe into drinking water. A study to identify and quantify volatile organic compound concentrations leaching into water in unused pipe segments demonstrated that organic components of polymerised pipes, including aromatic hydrocarbons, terpenoides and phenolic derivates can migrate into drinking water with the nature and concentrations of these leachates depending on pipe matrix and additives. Another study on the occurrence of antioxidant leachates in polyethylene pipeline found three different antioxidants in the water samples. A study on organic compounds in water in a series of cross-linked polyethylene, aluminium cross-linked polyethylene or polyethylene pipe segments from different manufacturers found not all compounds were detected in all pipe brands of the same polymeric material, showing the variability associated with polymers synthesised by different manufacturing processes. A study examining the migration into drinking water of phenolic antioxidants used to stabilise polypropylene pipe found the low molecular HEALTH STREAM
degradation product, 2,4-di-tert-butyl phenol was detected in aqueous extracts much more frequently than high molecular phenols. Greater amounts of phenols were extracted in alkali water, and temperature increase led to a significant increase of extractable phenols and total organic carbon. There were few studies available to comprehensively characterise the leaching or monomers and/or additives from polyvinyl chloride (PVC) and chlorinated polyvinyl chloride polymer materials. “Early-era� PVC potable water pipes tended to leach vinyl chloride monomer (VCM) into drinking water. After evidence demonstrated that this monomer was carcinogenic in both human and animal models, new guidelines limiting the amount of vinyl chloride residues permitted in PVC pipes were established. Pipes manufactured prior to the implementation of the new manufacturing process remain in use in many public water systems however and many continue to leach VCM into drinking water. Several studies have investigated the leaching into drinking water of organotins used as antioxidants in PVC and CPVC pipes. The presence of organotin compounds methyltin, dimethyltin and butyltins were detected in water samples from PVC pipes used in Canada. Studies of CPVC pipes showed organotin levels initially decreasing rapidly and then much more slowly suggesting that long-term leaching from new CPVC delivery systems was likely to occur. The majority of information on health hazards associated with exposure to drinking water leachates from plastic pipes comes from studies in animal models such as rats and mice although some data are available from human studies or case reports. The health effects of leachate chemicals are potentially significant, ranging from liver and kidney effects to adverse health outcomes on the reproductive, developmental, immune and nervous systems, endocrine disruption and/or carcinogenicity. Many of the substances target the same organs/systems, raising the possibility of additive or synergistic effects when considered as chemical mixtures. The results of modelling simulation and experimental exposure analysis suggests that the neurotoxic effects of individual chemical compounds will be additive over a range of doses.
SEPTEMBER 2008
PAGE 18
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
The impact of short-term exposures on sensitive or susceptible populations also needs to be considered. The developing nervous, reproductive, endocrine and other systems in fetuses, infants and children are much more vulnerable to the disrupting effects of toxic chemicals than adult organ systems. Infants and children consume more water per kg of body weight per day and therefore would be exposed to a relatively greater chemical dose than adults. Infants and young children spend more time indoors at home or in day care and therefore the contribution of residential and community drinking water supplies in these age groups may comprise a substantial proportion of the total environmental exposure for chemical leachates. Short-term elevations of leachates therefore may have significant health impacts on these most sensitive human subpopulation during critical developmental stages. Other health concerns include occupational exposure of workers; identification and characterisation of new chemicals used in manufacturing of polymeric tubing; interactions between the physical and chemical properties of drinking water in plastic pipes and their effect on disinfectant residuals and biogrowth promotion, and the effects of varying flow rates and residence time of water in premise plumbing plastic pipes. However drinking water is not the sole source of exposure to these compounds, and exposures may also occur from food and beverages, ambient air and soil. The relative importance of these different sources and different routes of exposure (ingestion, inhalation, dermal) is currently unknown. To protect public health it is necessary to identify compounds that migrate from plastic pipes into drinking water and to better assess the human health effects of these compounds and their degradates. Water Contamination Incidents Unintentional drinking-water contamination events of unknown origin: Surrogate for terrorism preparedness. Winston, G. and Leventhal, A. (2008) Journal of Water and Health, 6(SUPPL. 1); 11-19.
HEALTH STREAM
This paper discusses unintentional water contamination events that occurred in greater Tel Aviv Israel in 2001 and Camelford England in 1998, and how analysis of risk communication and management responses can assist strategies for possible deliberate contamination events. In July 2001 Israel’s national water company, Mekorot, discovered a ten-fold increase in turbidity and a 20- to 40-fold increase in the concentration of ammonia in the core water carrier pipeline in Tel Aviv. A directive was issued to the public not to drink tap water, including boiled water, until further notice. The region was then sealed and 150,000 cubic metres of water was drained and flushed with uncontaminated water. As the source of contamination could not be initially identified the water company suspected sabotage by terrorists. However the Ministry of Health and the Tel Aviv police concluded that it would not have been possible for such a large amount of ammonia to be introduced covertly into this part of the water supply system. The cause of the contamination was subsequently identified as being due to mechanical failure of the measuring buoy in an ammonia tank which resulted in 5 tons of ammonia being dumped into the drinking water reservoir. A survey conducted after the incident showed that the public regarded communication and management of the incident as satisfactory. In Camelford, England on 6 July, 1988 a serious unintentional drinking water contamination event occurred at the Lowermoor water treatment facility. A delivery driver dumped 20 tons of aluminium sulphate into the wrong tank at the Lowermoor treatment plant, resulting in high concentrations of the chemical entering the water supply system. The highly acidic water caused leaching of some toxic metals and corrosion of pipes and plumbing. Despite complaints of acid taste and irritation, the public was assured by a water authority spokesperson that the water was safe to drink. It took two days before the cause of the problem was identified and flushing of the system commenced. During the two contamination events (Tel Aviv and Camelford) different strategies were employed by the officials. The Israel Ministry of Health applied the
SEPTEMBER 2008
PAGE 19
COOPERATIVE RESEARCH CENTRE FOR WATER QUALITY AND TREATMENT
precautionary principle and informed the public immediately about the contamination and disclosed all that was known throughout every stage of the event. The public response and perception to the Tel Aviv water contamination event was guided by a different mind-set than the Camelford response. In Israel everyday life in under constant threat of terrorism and this has shaped the psychological and social structure. The Tel Aviv event was communicated to the public using emotionally charged words which created a risk perception that was greater than the actual risk. In contrast, during the Camelford incident there was no communication with consumers in the earliest stages of discovery of water contamination and many claims of health problems from the public were reported. This lack of openness and transparency in communication can lead to failure in bringing about satisfactory recovery and resolution especially in terms of consumer satisfaction. These contamination events can serve as a surrogate for an intentional terrorist attack on a municipal water supply, and can provide information to improve responses to future incidents. The Camelford incident illustrates a potential for a deliberate act to disseminate a large volume of a chemical or biological agent into the drinking water
supply. The Tel Aviv event revealed vulnerability and therefore security weaknesses by an instrument technical failure. When the turbidity increase was first detected, technical staff at Mekorot assumed this was due to an electronic fault in the turbidity meter. Toxicity testing was not done until late in the series of events, and there were delays in testing due to failure to utilise full laboratory capacity. This event led to an increase in awareness that a water crisis can occur outside the sphere of terrorism and revealed gaps in certain “readiness� directives for such events. The different strategies used by officials during the two water contamination events show how the risk management process can influence the outcomes and recovery phase of such incidents. These water contamination events highlight how lessons learned during peacetime can be used as preparation in the event of a terrorist breach of the public drinking water system.
Disclaimer Whilst every effort is made to reliably report the data and comments from the journal articles reviewed, no responsibility is taken for the accuracy of articles appearing in Health Stream, and readers are advised to refer to the original papers for full details of the research.
Health Stream is the quarterly newsletter of the Health and Aesthetics Program Group of the CRC for Water Quality and Treatment. 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 on the Web page of the CRC. Summaries of Web-bonus articles are available only in the electronic version. To be placed on the print version mailing list for Health Stream please send your postal address details to: Pam Hayes Epidemiology and Preventive Medicine Monash University - Central & Eastern Clinical School Alfred Hospital, Melbourne VIC 3004 AUSTRALIA
Phone +61 (0)3 9903 0571 Fax +61 (0)3 9903 0576 Email pam.hayes@med.monash.edu.au
To be placed on the email notification list for Health Stream, please fill in the form on our website under Publications, Join Our Mailing List: http://www.waterquality.crc.org.au Established and supported under the Australian Government's Cooperative Research Centres Program.
HEALTH STREAM
SEPTEMBER 2008
PAGE 20