Issues in Potable Reuse The Viability of Augmenting Drinking Water Supplies with Reclaimed Water (1998) / Chapter Skim
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5 Health-Effect Studies of Reuse Systems
5 Health-Effect Studies of Reuse Systems
Pages 164-207
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From page 164... ...
Most of the studies sought to analyze and compare the toxicological properties of reclaimed water to those of the current drinking water supply. Windhoek is the only city in the world that has implemented direct potable reuse.
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From page 165... ...
Since inception of the potable reuse project in 1962, reclaimed water has been blended with local storm water and river water prior to percolation. At the time of the study, reclaimed water supplied about 16 percent of the total inflow to the ground water basin.
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From page 166... ...
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From page 167... ...
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From page 168... ...
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From page 169... ...
They stated that further characterization of the molecular structure and biological effects of the large numbers of apparently mutagenic halogenated organic compounds in the various waters would be necessary to confirm whether those materials pose any health risk. Denver Potable Reuse Demonstration Project The 3.8 x 103 m3/day (1.0 million gallons per day (mgd)
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From page 170... ...
The studies found that the quality of reclaimed water from the Denver Potable Reuse Demonstration Plant equaled or exceeded that of the existing drinking water supply and that it exceeded all federal and state standards for definable constituents (Lauer and Rogers, 1996~. In addition, a two-year chronic toxicity/carcinogenicity study, which gave concentrated doses of organic samples to more than 1500 rats over two generations, revealed no toxicologic, carcinogenic, reproductive, or developmental effects.
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From page 171... ...
The Miramar water samples exhibited more mutagenic activity than those from the reclaimed water. The mouse micronucleus assay, which is a short-term assay that assesses genetic damage to the bone marrow of mice exposed to concentrates, was run on seven samples of both waters.
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From page 172... ...
The Hillsborough River water was disinfected with ozone prior to analysis to make it more analogous to the AWT pilot plant product water. Concentrated extracts from both the Hillsborough River water and the reclaimed water were used to create doses for toxicological testing at up to 1000 times the potential human exposure of a 70 kg (154-pound)
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From page 173... ...
surveys of mutagenic activity, and 3. integrated toxicological testing.
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From page 174... ...
Surveys of Mutagenic Activity Other studies used the Salmonella/microsome assay and other tests to simply compare reclaimed wastewater to other drinking water sources.
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From page 175... ...
(It actually is more reminiscent of the types of activity that have been associated with the industrially polluted Rhine River in Europe in a series of studies by Dutch workers (Kool et al., 1982~.) The Tampa project also used the Salmonella/microsome assay to compare mutagenic activity of reclaimed water to Hillsborough River water (the current water supply)
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From page 176... ...
The Potomac River study used in vitro testing procedures. Here the Ames test detected mutagenicity in both the blended influent and the finished drinking water at about the same levels and with the same frequency (approximately 50 percent of the time)
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From page 177... ...
HEALTH-EFFECT STUDIES OF REUSE SYSTEMS 177 Checking the ozone disinfection unit at San Diego's Aqua III water reclamation facility. Photo by foe Klein.
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From page 178... ...
The Denver study used organic concentrates from reclaimed water and the finished water for Denver's drinking water treatment plant to produce 150x and 500x doses. The samples were administered to whole animals.
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From page 179... ...
Tampa reported 20.9 percent recovery from ozone-disinfected Hillsborough River water and 9.1 percent from ozone-disinfected GAC product water (CH2M Hill, 1993~. Recovery in various OLAC studies ranged from less than 50 percent (Baird et al., 1980)
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From page 180... ...
Endocrine disrupters are specifically identified for evaluation of health impacts in the latest reauthorization of the Safe Drinking Water Act. A potentially important issue for potable use of reclaimed water is that chemicals producing endocrine disruption have been associated with municipal wastewater effluents (Sumpter, 1995~.
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From page 181... ...
For potable reuse projects, continuous toxicity testing is desirable to provide project operations with an additional "warning system" in the event of unanticipated changes in product water quality. Conventional methods of toxicity testing do not allow for such continuous monitoring and the production of rapid results.
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From page 182... ...
Potential New Approaches for Judging the Safety of New Water Sources Potable reuse projects need a new approach to toxicity testing. Future toxicological characterizations of wastewaters intended for potable reuse or water derived for potable use from wastewaters should focus specifically on data needed for risk assessment.
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From page 183... ...
4. In vitro short-term testing could be confined to qualitative evaluations of particular toxicological effects found in the product water in order to identify potential contaminants and quickly guide remedial actions.
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From page 184... ...
Other recent research has focused on the similarity of the responses of aquatic species and mammalian species to endocrine disruption (Kavlock et al., 1996; Nimrod and Benson, 1996; Sumpter, 1995; Toppari et al., 1996~. Although fish have important advantages as toxicological test organisms, they also have disadvantages that are important to recognize.
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From page 185... ...
Similar biochemical relationships between fish and mammals may affect the development of some health problems. For instance, carcinogens in general induce tumors in a variety of organs in mammalian species, while in fish the liver appears to be the primary target (Bailey et al., 1996; Bunton, 1996~.
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From page 186... ...
The relationship of known responses in fish and mammals would have to be better established. As an initial step, the existing database on toxicological tests in fish could be rigorously compared to toxicological results that have been obtained in rodent species and, where data exist, in humans.
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From page 187... ...
In humans, the gastrointestinal tract greatly diminishes the importance of these irritant effects when exposure is through drinking water. Therefore, the wastewater must be of a quality that sustains fish for their normal life spans so that chronic effects can be examined.
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From page 188... ...
Detection of day-to-day variability is both impractical and unnecessary for health threats from chronic effects. However, the assessment of seasonal changes in water quality may be useful.
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From page 189... ...
The alternative is to identify the specific chemical responsible for the observed effect and to reduce the risk associated with that chemical. EPIDEMIOLOGIC STUDIES In two locations, Los Angeles County and Windhoek, South Africa, potable reuse systems operational for some time have been the subjects of epidemiological studies.
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From page 190... ...
Study Design Using an ecologic study design, epidemiologic studies of the health effects associated with the Windhoek reclaimed water supply began in 1973 and were expanded in 1976. Morbidity data were collected from private health care providers, hospitals, clinics, and health authorities.
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From page 191... ...
of the diarrhea episodes reported at Windhoek occurred in children under 14 years of age. Diarrheal disease incidence was much higher in black and colored children than in white children, regardless of water supply.
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From page 192... ...
In contrast, the rates of enteric infectious diseases reported to the Los Angeles County Health Department over the period 1989-1990 were 0.75 case per 1000 people per year in the population in the control areas and 0.9 case per 1000 people per year in the population using reclaimed water. Orange and Los Angeles Counties Health-Effect Study Two epidemiologic studies have been conducted by Orange and Los Angeles Counties in the Montebello Forebay area of Los Angeles County to examine health risks associated with exposure to reclaimed water used to replenish the area's ground water supply.
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From page 193... ...
Study Design Both studies used an ecologic study design in which the unit of analysis was the census tract. Each census tract was assigned a categorical exposure variable derived from estimates of the percentage of reclaimed water in the water supply, as determined by the water suppliers serving the area.
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From page 194... ...
Colorado River water, which has been used since 1954 to replenish the Montebello Forebay ground water basin, has high sulfate concentrations that allow its movement to be traced. Reclaimed water, by contrast, has no such characteristic mineral composition.
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From page 195... ...
: average percentage of reclaimed water = For the analyses using infectious disease health outcomes, the five exposure categories were based on three-year averages of the percentage of reclaimed water in order to reflect the shorter incubation period of infectious diseases. Three control areas areas of 15,21, and 81 census tracts in Los Angeles County were chosen from water systems that had never used reclaimed water.
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From page 196... ...
Study Findings and Interpretation of Results Overall, neither study observed consistently higher rates of either general or specific mortality or morbidity in the populations who lived in areas receiving higher percentages of reclaimed water. The first study reported higher but statistically insignificant rectum cancer mortality rates in the three areas receiving reclaimed water compared to the control areas, and the area with the higher percentage of reclaimed water (5 to 19 percent)
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From page 197... ...
In both studies, some significantly higher disease and/or mortality rates were observed both in some of the study areas that received reclaimed water and in some of the control areas. In their final interpretation of these results, the investigators considered the overall pattern of the results and whether the association between an exposure and a particular health outcome indicated a causal relationship, using commonly recognized criteria for causality (strength of the relationship, consistency, temporality, biologic gradient or dose-response, plausibility, and coherence)
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From page 198... ...
The only health outcomes that were not included in these studies were reproductive outcomes (spontaneous abortions, birth defects, and infant mortality) , which could be influenced by both acute and chronic exposures to contaminants in drinking water.
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From page 199... ...
Therefore, in this study the risks associated with exposure to reclaimed water cannot be adequately evaluated for several important health outcomes because of the small number of events. Although the overall analyses do not suggest an association between adverse outcomes and reclaimed water in the drinking water supply, the public health significance of no or low rates of incidence, especially for specific outcomes, should always be interpreted in light of the statistical power of a study to detect an elevated risk.
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From page 200... ...
The study sought to provide baseline health information on the residents of San Diego County that could be compared to future epidemiologic monitoring of health effects if potable reuse was adopted. This study also evaluated the feasibility, logistics, and cost of collecting various health data.
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From page 201... ...
The interpretation of the results from surveys of mutagenic activity is subject to the same ambiguity identified with other studies that have depended primarily on in vitro test systems. While the studies appeared to show no differences between reclaimed water and the conventional water source, positive results were obtained in screening assays, and there was no attempt to collect data in a system that would allow a rigorous comparison of relative risks associated with these two water sources.
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From page 202... ...
Because of the high cost and methodological problems inherent in the testing of concentrated samples on rats and mice and because of the difficulty in applying the logic of safety testing to reclaimed water, the strategy set forth by the 1982 National Research Council panel is potentially too costly to implement and will not resolve health-effect questions in a timely manner for an operational potable reuse system. Accordingly, the committee recommends the following: · A new, alternative approach, such as the fish system described in this chapter, should be developed and used to continuously test the toxicity of reclaimed water in potable reuse projects.
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From page 203... ...
Epidemiology Studies Numerous epidemiologic studies (ecological, case-control, cohort, and outbreak investigations) have examined the relationship between various microbial and chemical contaminants in drinking water and a wide range of acute and chronic health outcomes in populations exposed either to a specific contaminated water supply or to specific types of source waters and treatment processes.
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From page 204... ...
The committee recommends that alternative epidemiologic study designs and more sophisticated methods of exposure assessment and outcome measurement be undertaken at a national level to evaluate the potential health risks associated with reclaimed water. Ecologic studies should be conducted in a variety of water reuse situations (e.g., ground water, surface water)
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From page 205... ...
1995. Disinfection by-products in drinking water: Critical issues in health effects research.
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From page 206... ...
1982. Presence, introduction and removal of mutagenic activity during the preparation of drinking water in the Netherlands.
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From page 207... ...
Pp. 30-31 in Disinfection By-Products in Drinking Water: Critical Issues in Health Effects Research.
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