Health Stream Issue 17

Following the water contamination incidents in Sydney during late 1998, the management of water supplies for the city was restructured by the NSW state government (1). Responsibility for management of the catchment and storage dams was transferred from the Sydney Water Corporation to the newly formed Sydney Catchment Authority (SCA). The Act of Parliament establishing the SCA also required that an audit of the catchment be carried out within a five month interval of its formation.

The audit was designed to provide information to the SCA, state and local government departments and other relevant organisations to assist in the future management of the catchment, and in the development of specific programs for catchment improvement and pollution control. The audit will also be pivotal in the preparation of a Regional Environmental Plan for the catchment.

A team of experts led by Dr John Williams, Deputy Chief of CSIRO Land and Water, was appointed to perform the audit. The team was assisted by an Independent Reference Panel representing eleven organisations with broad expertise and first-hand knowledge of the catchment. The final report of the Catchment Audit was delivered to the NSW Minister for the Environment in December 1999 and publicly released in January 2000 (2).

The report provides a "snapshot" of the present state of the catchment and the many challenges that must be overcome in order to improve the protection of public health and ecosystem integrity. It also identifies a number of gaps in knowledge which currently hamper the development and assessment of management strategies. In many instances these relate not only to the specific circumstances of the Sydney catchment area, but also to general limitations of existing knowledge of catchment ecology.

The Terms of Reference required that the Catchment Audit should compile and categorise information on the state of the catchment (in terms of attributes such as water quality, physical attributes, fauna and flora, cultural values etc), and the pressures to which the catchment is subject (in terms of human activities, land uses, natural processes etc).

Prior to the audit, the SCA had assembled an extensive report summarising available information sources and data collections, and preliminary set of indicator measures had been developed in conjunction with experts from the CRC for Freshwater Ecology. The audit team carried out ground inspections of several areas of the catchment and made a comprehensive helicopter inspection of major river systems, as well as examining existing documentation. Landsat TM satellite imagery was also used to assess the state of the catchment area.

The audit team found that a very large volume of information was available on the catchment area in the form of numerous reports, investigations, and monitoring data. However there had been only limited attempts to integrate this knowledge to form a comprehensive picture of the condition of the whole catchment.

The SCA holds detailed information on the Special Areas (the "inner catchment" which was under the direct control of the Sydney Water Corporation), but has very limited knowledge on the remainder of the catchment (the "outer catchment" comprising over 70% of the total area). Much of the information on the outer catchment compiled for the audit was obtained from other State agencies and organisations.

The audit team recommended that the first priority for the SCA should be to assemble and organise the biogeographic spatial data for the catchment area. This should be followed by strategic planning of a program to fill the identified gaps in knowledge and information. The team also proposed an expanded set of indicators based on the findings of the audit, and recommended that these be further developed in consultation with stakeholders and technical experts. It will be necessary to implement assessments of small areas in order to adequately describe the diverse nature of the catchments.

Overall, the report classified the state of the Sydney catchments as "reasonably good", with about 10% of the total area of 16,000 square kilometres considered to be "poor" while about 25% was rated as "excellent". However past management practices which concentrated heavily on protection of "Special Areas" around major storage reservoirs were deemed to be insufficient to maintain adequate protection of water quality. These areas are largely protected from residential and agricultural development but comprise less than 30% of the total catchment.

The audit team expressed the opinion that past dependence on the Special Areas to protect water quality had distorted the allocation of resources for monitoring and managing the catchment. Extensive agricultural and residential pressures on other areas of the catchment are contributing to increased hazards for water quality and catchment health, and a more integrated management strategy for the whole catchment area is now urgently required.

At present the SCA has limited powers governing regions outside the Special Areas, and SCA regulations can be overridden by a number of other agencies. The operations of at least 17 government instrumentalities have the potential to affect catchment health or water quality. The report concludes that successful implementation of a whole-of-catchment management plan will require the support of legislative power and policy to enable vigorous control of land use.

The audit team emphasise that adequate levels of resourcing, and active involvement and ownership by local government, state agencies and the community will also be essential. They recommend that the SCA builds in-house expertise and knowledge rather than relying on external consultants. The whole-of-catchment management plan must also be incorporated into the Regional Environmental Plan and other regional planning processes.

According to a report in the January 5 edition of the Sydney Morning Herald, the NSW government is already moving to strengthen the regulatory powers of the SCA. Applications for approval of developments in the catchment will soon have to include a water cycle management strategy explaining how water quality would be protected or improved by the development.

However, the NSW Opposition party has cautioned that granting broad additional powers as recommended in the Audit Report will result in the SCA becoming a "super-power agency" overriding existing local government, EPA and planning controls.

(2) Audit of the Hydrological Catchments managed by the Sydney Catchment Authority. Final Report to the Minister for the Environment, NSW State Government, December 1999. CSIRO Land and Water. The report can be downloaded from:

In recent decades regulators in the US have concentrated heavily on the microbiological health risks associated with surface water supplies, and have introduced progressively stricter microbiological standards for finished water and performance criteria for water treatment plants. In contrast, regulations for groundwater supplies are less stringent with no specific requirements for primary disinfection or maintenance of disinfectant residuals for groundwater sources not under the influence of surface water. However, increasing evidence of chemical and microbial contamination of groundwater supplies, and threats to reliability from over-pumping have resulted in an increase in regulatory attention (1).

The US EPA is now entering the final stages of revisions to the Ground Water Rule, which governs public groundwater supply systems. For the first time the Rule will require all public groundwater supplies to be disinfected, even if they are not under the influence of surface water. In addition, substantial efforts are being made to expand and coordinate monitoring and management programs to improve understanding of the condition of groundwater supplies.

At least 400,000 public drinking water wells presently exist in the US, serving a population of about 110 million people. An additional 20 million people obtain their drinking water from private wells, making a total of 130 million (48% of the total US population of 268 million). Almost 95% of rural populations rely on groundwater for drinking and domestic use, and over 40% of water used for crop irrigation and livestock watering in the US comes from groundwater. Groundwater also contributes up to half of the water flow in surface streams.

Groundwater supplies have been traditionally viewed as having relatively low risks of microbiological contamination compared to surface water supplies, however a recent review of such supplies in the US has questioned this assumption (2). Researchers in the US EPA suggest that many groundwater supplies pose health risks to consumers, and advocate implementation of disinfection as a minimal protective measure for all groundwater supplies.

The authors review published studies on groundwater contamination and also note the existence of a substantial number of unpublished surveys. Although some studies have involved sampling of large numbers of wells, selection criteria were variable and in most cases only one sample was taken from each site. A large survey (244 samples from public wells) carried out by the American Water Works Association Research Foundation reported the presence of various indicators of faecal contamination in 50% of wells considered to be more vulnerable to contamination, and in 40% of wells considered less vulnerable.

In another survey of 30 US public wells thought to be vulnerable to contamination, 24% were positive for culturable viruses, more than 50% positive for coliphage, 50% positive for E. coli and 70% positive for enterococci in at least one monthly sample over a one year period. Canadian researchers have also reported high rates of contamination, with the faecal indicator Clostridium perfringens found in 20% of 300 rural wells tested (3). These and other studies suggest that many groundwater sources are prone to faecal contamination but the fragmentary nature of the data makes it difficult to estimate the scope of the problem on a national level.

Groundwater supplies were responsible for 58% of the 614 drinking water related disease outbreaks in the US reported to the Centers for Disease Control and Prevention between 1971 and 1994. About 30% of these outbreaks were attributed to contamination of distribution systems, and the remaining 70% to contamination of the groundwater source. During 1995 and 1996 groundwater supplies were associated with 11 of 15 drinking water related outbreaks attributed to infectious agents (4).

In addition to recognised outbreaks reported to CDC, it is likely that substantial numbers of people are affected by unreported outbreaks or by small outbreaks that are not detected by health authorities. Some epidemiological studies have suggested that waterborne pathogens may be responsible for a significant portion of endemic gastrointestinal illness, although the evidence on this issue is not conclusive.

The authors of the recent review (2) believe that groundwater systems may now constitute a greater threat to public health than surface waters because of the lower rates of use of disinfection and absence of filtration in groundwater supplies. In order to derive an estimate the possible magnitude of the problem, they developed a quantitative risk assessment model based on available knowledge of groundwater contamination.

This model assumed faecal contamination rates between 7% and 46% of wells, presence of human infectious viruses in 46% of contaminated wells, a population of 27 million people drinking predominantly from undisinfected groundwater systems, and dose-response models for rotavirus infection. This model resulted in an estimate of 890,000 to 5.9 million illnesses per year attributable to undisinfected groundwater sources, associated with a possible mortality of 1,400 to 9,400 per year (assuming a 1% death rate among elderly people who suffer gastroenteritis).

A number of approaches for controlling microbial contamination of groundwater sources were also reviewed and available evidence on their efficacy was examined. There appear to have been few assessments of well-head protection programs, but the results suggest that such measures have not reduced contamination rates. However US states which consider hydrogeological criteria for siting wells had fewer reported violations of the Total Coliform Rule (TCR) than states which did not use these criteria. Analysis of violation rates for the TCR vs the proportion of groundwater supplies which are disinfected in each state showed a marked inverse relationship. The ten states with highest rates of disinfection showed an 18% violation rate over 5 years, whereas the ten states with the least disinfection had a violation rate of 38%.

The authors conclude that while considerably more information is needed to establish the extent and health impact of microbial contamination of groundwater, the introduction of disinfection for all groundwater systems would be "prudent public health policy".

This workshop was attended by over 20 invited participants, representing a broad spectrum of Australian water industry, research and public health interests. International guests included Dr George Di Giovanni (American Water Works Service Company), Dr Rachel Chalmers (Director of the Cryptosporidium Reference Laboratory, UK) and Dr Jim McLauchlin (Public Health Laboratory Service, UK). The workshop produced a series of initiatives to build a strong collaborative Cryptosporidium research program in Australia, with potential for expansion to an international level.

This meeting was prompted in part by a workshop held at Tadley Court in the UK during August 1999 (1). The Tadley Court workshop discussed observations that Cryptosporidium oocyst sources and preparation methods may impact on viability, and highlighted the problems associated with the use of different (and often poorly described) methods in published studies which severely limited the comparability of results. The participants developed a number of best practice protocols for oocyst preparation, cell culture, disinfection and treatment studies, reporting of results, and quality assurance and quality control for Cryptosporidium research.

Dr John Langford, Executive Director of WSAA, opened the Sydney workshop with a brief introduction to WSAA and a review its research program on a range of issues relating to water quality and human health. WSAA was a founding partner in the CRC for Water Quality and Treatment, and is co-funding a number of projects including the Water Quality Study (a randomised controlled trial on the effect of drinking water treatment on gastroenteritis), and Case-control studies of risk factors for cryptosporidiosis. In addition to its involvement in the CRCWQT, WSAA also conducts an independent research program. The process of developing the WSAA research agenda involves strategic workshops to discuss industry needs, define gaps in current knowledge, and assess the feasibility of different research approaches.

After outlining the five specific objectives of this workshop on viability testing and genetic typing of Cryptosporidium oocysts, Dr Langford then introduced Dr George Di Giovanni to lead the discussion on the first objective.

Objective 1 - to define the research and technology transfer necessary to refine and establish in vitro procedures for the maintenance of Cryptosporidium parvum isolates of both the human and cattle genotypes (Genotype 1 and 2).

Dr Di Giovanni has successfully combined cell culture and PCR techniques to develop a method for the specific detection of C. parvum oocysts that are infectious for humans (2). The method utilises filtration and immunomagnetic separation to purify oocysts from environmental samples, followed by inoculation into human HCT-8 enterocyte cell monolayers in microtitre tray wells. After a 72 hour incubation to allow replication of infectious oocysts within the human cells, the monolayers are washed to remove any unexcysted oocysts, then the cells are lysed and PCR is used to amplify a 361 basepair DNA product from the C. parvum heatshock protein (hsp70) gene. The amplified segment is then DNA sequenced to determine the genotype.

The cell culture method permits the growth of both the Type 1 (human) and Type 2 (cattle) genotypes of C. parvum and has been used to test the three Type 2 isolates used in human volunteer studies. These three isolates showed large differences in infectivity in the human volunteers, and this correlated strongly with infectivity in HCT-8 cell cultures. Thus the technique appears to represent a relevant laboratory model for human infection. However, the protozoa are not able to form new oocysts to complete the entire infection cycle, and the cell cultures can be maintained only for a limited time. Nevertheless, this method offers a more rapid and lower cost alternative to animal infection studies.

The cell culture technique is sufficiently sensitive to detect a single viable oocyst, and has been successfully employed to detect viable oocysts in finished water, raw water and filter backwash samples. Ongoing experimental work is aimed at optimising excystation and cell culture conditions, and adapting the method to yield semi-quantitative information on viable oocysts numbers so that it can be more easily applied to disinfection studies.

The workshop participants agreed that coordinated efforts should be made to establish this cell culture technique in Australian laboratories, and carry out inter-laboratory comparisons to ensure that results were reproducible. The following strategy was suggested for implementation:

Dr Duncan Veal from Macquarie University and Dr Paul Monis from the Australian Water Quality Centre outlined the properties of the two methods under discussion. These procedures are already in use in a number of Australian laboratories as surrogate markers for oocyst viability or infectivity, however they have not yet been validated against cell culture or animal infection methods. Some work on validation is presently underway in the US and the UK.

The FISH method detects the presence of ribosomal RNA sequences (rRNA) which are believed to degrade relatively quickly after oocysts become inviable. As rRNA contains both highly conserved and highly variable regions, it is possible to use different probes to detect either all Cryptosporidium species, or C. parvum in particular. The results can be scored using an epifluorescence microscope or using flow cytometry, giving quantitative results on the number of "viable" oocysts.

The RT-PCR method detects messenger RNA (mRNA) which codes for the heatshock protein (hsp70). Again, this molecule is believed to degrade relatively quickly after oocysts become inviable. The method has the ability to detect either all Cryptosporidium species, or C. parvum specifically depending on the probe used. The outcome is essentially a presence /absence result for "viable" oocysts without quantitation.

The participants agreed that following establishment of the HCT-8 cell culture technique in Australia, a study should be carried out to compare the results of FISH, RT-PCR and cell culture methods. This should be carried out in a blinded fashion with samples of fresh oocysts, killed oocysts and aged oocysts (which would be expected to have declined in viability) from several isolates. In order to provide statistically reliable results, it was recommended that a biometrician be involved in the study design, and that further discussions be held when a draft protocol was available for consideration.

Objective 3 - to develop strategies for a multi-centre trail within Australia and overseas to compare currently existing PCR based detection procedures for Cryptosporidium with the aim of evaluating broad applicability in terms of specificity and sensitivity.

Objective 4 - to develop strategies for a multi-centre trial within Australia and overseas to compare currently existing PCR based genotyping techniques in order to determine the most useful genetic loci.

Discussion on these objectives was introduced by Dr Una Morgan of Murdoch University, who began by outlining the requirements for a testing procedure in terms of sensitivity, reproducibility and speed. A decision needs to be made on whether the method should be able to detect all species of Cryptosporidium, all genotypes of C. parvum, or only those genotypes currently known to infect humans with normal immune systems (ie Genotypes 1 and 2). Ideally the method should also have the capability to determine the genotype.

Dr Morgan then summarised the current state of knowledge on Cryptosporidium genotyping. The taxonomy of this organism is currently under review as increasing knowledge from molecular characterisation reveals details of phylogenetic relationships. For C. parvum it is likely that some of the currently recognised genotypes will eventually be designated as separate species. At present 7 distinct major genotypes are classified within C. parvum; Type 1 (human), Type 2 (cattle), marsupial, pig, mouse, ferret, and dog. A minor variant of Type 1 occurs in monkeys. The dog genotype is soon likely to be reclassified as a separate species (C. canis), while the cat genotype is already recognised as such (C. felis).

A number of genetic loci have been examined for their ability to distinguish between different species of Cryptosporidium, and to discriminate between major genotypes within a species. There have been some discrepancies in results reported by different laboratories, perhaps due to different methodology. Overall, it appears that the 18s rRNA gene and the Hsp70 gene provide the best markers for reliably distinguishing between species and major genotypes.

Extensive efforts have also been made by a number of laboratories to develop markers for distinguishing between isolates within a genotype, however the results have been disappointing. Genome sequencing projects are underway, with the aim of determining the entire sequence of the Iowa (Type 2) isolate and at least 65% of the sequence of the NEMC1 (Type 1) isolate. This knowledge may assist in designing new probes for genotyping individual isolates.

After further discussion it was agreed that collaborating Australian laboratories would undertake to perform an analysis with standard markers, primers, and a reference strain (and/or DNA clones) when characterising isolates in order to provide consistent data for comparison. These standards were agreed to comprise the 18s rRNA and Hsp70 markers, with the Iowa strain or clones of its DNA. Collaboration will also be sought in the UK via the National Cryptosporidium Research Steering Committee and in the US via AWWARF. It was agreed that consideration should be given to establishing a database of verified Cryptosporidium DNA sequence data to assist the collaborative research effort.

On the topic of avenues for seeking new markers to distinguish between isolates, Dr Duncan Veal suggested that the science of "proteomics" might offer some promise. This methodology involves the automated analysis of differences in protein content between isolates. This may enhance the probability of finding strain-specific markers. It was agreed that a preliminary research proposal for this approach should be developed.

Objective 5 - to explore strategies for determining the prevalence and distribution of human infectious and non-infectious genotypes in different water sources, and in populations of human and animal hosts.

Dr Andrew Thompson from Murdoch University introduced this topic and highlighted the need for a diverse collection of isolates from animal, human and environmental sources in order to gain the maximum knowledge from genotyping studies.

Dr Jim McLauchlin then presented the findings of genotyping studies done in the UK by the Public Health Laboratory Service. Analysis of isolates from eight drinking water Cryptosporidium outbreaks in the UK demonstrated that five outbreaks were due to Type 1 isolates (indicating human faecal pollution) while three were due to Type 2 isolates (human or animal faecal pollution). For five swimming pool related outbreaks examined, two were of Type 1, two were of Type 2 and one was mixed Types 1 and 2.

Seasonal trends in prevalence in sporadic cases (not related to outbreaks) showed that the Type 1 genotype is rarely isolated in winter, while the Type 2 genotype is found all year round. The incidence of reported cases and the ratio of Type 1 and Type 2 isolates varies in different regions. Data on farm animal infections show a consistent peak of infection in sheep during springtime (lambing season), while in cattle infection peaks occur both in spring and in autumn.

Overall, the two major C. parvum genotypes (Types 1 and 2) account for at least 96% of human infections in the UK. An apparently novel genotype (Type 3) has been found recently but has not been well characterised.

Human sources Some participants at the workshop have established ongoing relationships with hospitals or pathology laboratories, but these sources are limited. A number of possible mechanisms to obtain isolates were discussed:

It was agreed that the first option should be explored as the most simple and lowest cost alternative. Dr Geoff Hogg of Melbourne University suggested that the cooperation of the Public Health Laboratory Network should be sought initially, and then commercial pathology labs should be approached. Cryptosporidium-positive faecal specimens reported to Health departments in Victoria and South Australia are already being collected as part of a CRC for Water Quality and Treatment Case-control study.

Environmental sources Some Australian water authorities are testing environmental samples for Cryptosporidium, but in many cases the entire sample is used in the test procedure. Taking duplicate water samples is expensive, and the low oocyst numbers and often poor recovery rates, oocysts may not be recovered from both samples.

Dr Jim McLaughlin reported that he had achieved some success with attempts to remove oocysts from slides after microscopic examination and genotype them. Dr Chris Saint and Dr Paul Monis from the Australian Water Quality Centre agreed to carry out preliminary experiments of this nature to see if a reliable technique could be developed and report back to the group.

Dr Duncan Veal noted that the SCA had agreed to forward positive samples from their sampling program to him for genotyping, and Dr David Roser from the University of NSW undertook to seek similar cooperation from water authorities participating in the CRCWQT Pathogens in Catchments Project.

Animal strains Participants with expertise in this area reported that tests for Cryptosporidium are rarely done in routine veterinary practice. Most isolates of this nature have to be obtained from specific research projects. Some Australian water authorities are supporting research programs to examine the carriage of Cryptosporidium in catchment animals.

Conclusion Dr John Langford concluded the workshop by summarising the agreed strategy and actions developed for each objective, and thanked participants for their valuable input. The proposed research strategy will now be presented to the WSAA Research Committee for consideration and further development.

(1) Towards a standardised experimental design for viability and inactivation studies. Report on a Workshop on Cryptosporidium and Water Chaired by Professor Ian Bouchier Held at Tadley Court, Tadley, Hampshire on 11-12 August 1999. http://www.dwi.detr.gov.uk/pubs/

(2) Detection of infectious Cryptosporidium parvum oocysts in surface and filter backwash water samples by immunomagnetic separation and integrated cell culture-PCR. Di Giovanni, G. D., F. H. Hashemi, et al. (1999). Appl Environ Microbiol 65(8): 3427-32.

The E. coli O157:H7 outbreak that hit the Washington County Fair in August last year has resulted in lawsuits seeking millions of dollars in damages. Over 1,000 people became ill and two people died after drinking unchlorinated well water during the Fair. One of several wells on the site is believed to have been contaminated by waste seepage or runoff from a nearby dairy farm after heavy rains.

The Fairground is operated by a small non-profit community group which holds public liability insurance of only $1 million. The group is presently engaged in a legal dispute with the insurance company which is arguing that a policy clause exempting damage from storm and wastewater pollution of sewer systems or streams is applicable in this instance.

The outbreak has highlighted the risks faced by many small water supply systems in the US, and variations in state requirements for insurance coverage for system operators. It is believed many small to medium operators have inadequate insurance cover and seldom hold policies covering their officers and directors. This may leave individuals personally liable for damages settlements in cases such as this.

A British pediatrician has advised parents to sue schools which do not provide drinking fountains for children. Dr Trevor Brocklehurst of the St James University Hospital in Leeds said that many schools have removed water fountains and substituted softdrink vending machines in their place, leaving children with little opportunity to obtain plain water. Dr Brocklehurst has raised the issue with the Leeds Health Authority, claiming that children he is treating for urinary tract infections are being placed at risk of complications by lack of access to water at school. The Leeds Health Authority is undertaking a study on the extent of the problem, and says it is working with local education authorities to ensure drinking water is readily available at all schools.

The US National Research Council has released a report recommending that the current maximum contaminant level goal (MCLG) of 1.3 mg/L should be retained by the EPA. Water supplies where the 90th percentile of first flush samples exceeds the MCLG may be required to take remedial action. The Council was asked to review the scientific and technical basis for the level after epidemiological studies in Nebraska and Delaware failed to show adverse effects in people consuming drinking water with high copper levels.

Copper is an essential human nutrient but can also cause acute gastrointestinal symptoms and longer term toxicity when ingested at higher doses. Children are more vulnerable to copper toxicity than adults, and people suffering from several genetic conditions may be affected even by low levels. The committee concluded that conventional risk assessment using chronic toxicity endpoints and safety factors was not applicable in this case because of the essential nature of copper, its metabolic regulation and the narrow range of acceptable intake levels. Further research is needed to better define vulnerable groups and to estimate total copper intake from drinking water and other sources.

The US EPA has asked the District of Columbia Court of Appeal to postpone hearings on the case brought against it by the Chlorine Chemistry Council. As reported in Health Stream Issue 16, the CCC has filed a suit asking the Court to set aside the EPA Maximum Contaminant Goal Level of zero for chloroform, and order the EPA to set a non-zero MCLG based on scientific evidence. The EPA is seeking to delay the case on the grounds that the zero MCLG was set as an "interim risk management decision" in response to a Congressional deadline, while additional scientific information was still being sought. New evidence in the form of a report from the Science Advisory Board is now available, and the EPA has argued that proceeding with the current court case would be an inefficient use of time and resources for all parties.

Water supply and distribution has been recognised as one of the top engineering achievements of the 20th century by the US National Academy of Engineering. Water supply ranked 4th in the list of achievements after Electrification, Automobiles and Airplanes.

The 4^th Annual Australian Environmental Engineering Research Event provides postgraduate students of Environmental Engineering and related disciplines an opportunity to present and discuss their work in a friendly, informal atmosphere. A selection of prominent international and local speakers has been invited.

The Event will be held in Victor Harbor, South Australia, 21 - 24 November 2000. The theme of the event, “Environmental disciplines working together for a sustainable future”, will address students from a wide variety of disciplines. One of the highlights of previous events has been the lateral communication between postgraduate researchers of different scientific and engineering disciplines, and we are keen to maintain this tradition.

Thus we encourage any postgraduate students working in the environmental field to attend, whether they are Engineers or Scientists. Postgraduate students interested in attending must either present a poster presentation or a platform presentation. There is a call for abstracts, which are due 19^th May 2000. Sponsorship opportunities are currently available.

Lionel Ho CRC for Water Quality and Treatment Private Mail Bag 3 SALISBURY SA 5108 Phone: (08) 8259 0365 Fax: (08) 8259 0228 Email: lionel.ho@sawater.sa.gov.au	Rachel Prince School of Engineering and Science Swinburne University of Technology Mail 38, PO Box 218 HAWTHORN VIC 3122 Phone: (03) 9214 8639 Fax: (03) 9819 6443 Email: rprince@swin.edu.au	Sam Brooke CRC for Water Quality and Treatment Private Mail Bag 3 SALISBURY SA 5108 Phone: (08) 8259 0347 Fax: (08) 8259 0228 Email: sam.brooke@sawater.sa.gov.au
The CRC for Water Quality and Treatment is a Gold Sponsor of EERE 2000.

In 1997/98, NHMRC/ARMCANZ commenced a rolling revision of the Australian Drinking Water Guidelines (ADWG). This rolling-revision provides an opportunity to revise individual water quality parameters each year to ensure the guidelines represent the most up to date scientific understanding.

The NHMRC/ARMCANZ Drinking Water Coordinating Group is currently seeking advice in relation to priority areas to be considered for the 2000/01 phase of the ADWG rolling-review. The following information outlines the areas that have been revised since 1998.

The NHMRC/ARMCANZ Drinking Water Coordinating Group is currently considering developing a work program for 2000/01 and would welcome input into establishing priority issues for consideration during the ADWG rolling-review process. Advice is being sought on issues that should be considered during the forthcoming year.

Following its endorsement in 1996, the ADWG has been subjected to a Rolling Revision process that ensures the Guidelines represent the latest scientific evidence in relation to good quality drinking water. From time-to-time, as sections of the Guidelines are reviewed, the Web site will be updated to provide the latest information.

The production of the PDF version of the ADWG has been organised and sponsored by the Cooperative Research Centre for Water Quality and Treatment as a service to the Australian water industry.

The printed version of Health Stream is available free of charge - to be added to our mailing list please contact Pam Lightbody (email above or fax + 61 3 9903 0576). Past issues can be found under Publications, and there is a searchable archive of articles, news items and literature summaries.

Editor - Martha Sinclair	email martha.sinclair@med.monash.edu.au
Assistant Editor - Pam Lightbody	email pam.lightbody@med.monash.edu.au