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Microbiological & Chemical Exposure Assessment Research Division Publications: 2008
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This page lists publication titles, citations and abstracts produced by NERL's Microbiological & Chemical Exposure Assessment Research Division for the year 2009, organized by Publication Type. Your search has returned
23 Matching Entries.
See also Microbiological & Chemical Exposure Assessment Research Division citations with abstracts:
1999,
2000,
2001,
2002,
2003,
2004,
2005,
2006,
2007,
2008,
2009
Technical Information Manager: Angela Moore - (513) 569-7341 or moore.angela@epa.gov
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Presented/Published |
| JOURNAL |
Predicting Virulence of Aeromonas Isolates Based-on Changes in Transcription of C-Jun and C-Fos in Human Tissue Culture Cells |
09/01/2009
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HAYES, S. L., M. Waltmann, M. J. DONOHUE, D. J. LYE, AND S. J. VESPER. Predicting Virulence of Aeromonas Isolates Based-on Changes in Transcription of C-Jun and C-Fos in Human Tissue Culture Cells. JOURNAL OF APPLIED MICROBIOLOGY. Blackwell Publishing, Malden, MA, 107(3):964-969, (2009).
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Aims: To assess virulence of Aeromonas isolates based on the change in regulation of c-jun and c-fos in the human intestinal tissue culture cell line Caco-2.
Methods and Results: Aeromonas cells were added to Caco-2 cells at approximately a one to one ratio. After 1, 2 and 3 hours incubation at 37oC, mRNA was extracted from the cells and gene expression of two host genes, c-jun and c-fos, quantified. Aeromonas isolates which were virulent in the neonatal mouse model demonstrated up-regulation of c-jun and c-fos compared to avirulent isolates.
Conclusions: Human cell culture results showed that c-jun and c-fos were predictive of Aeromonas virulence.
Significance and Impact of the Study: An Aeromonas relative virulence scale (ARVS) is proposed for use in the testing of Aeromonas drinking water isolates.
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| JOURNAL |
The Determination of Pesticidal and Non-Pesticidal Organotin Compounds in Water Matrices By in Situ Ethylation and Gas Chromatography With Pulsed Flame Photometric Detection |
07/01/2009
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EVANS, O. M., P. KAUFFMAN, A. M. PAWLECKI-VONDERHEIDE, L. J. WYMER, AND J. N. MORGAN. The Determination of Pesticidal and Non-Pesticidal Organotin Compounds in Water Matrices By in Situ Ethylation and Gas Chromatography With Pulsed Flame Photometric Detection. Microchemical Journal. Elsevier BV, AMSTERDAM, Netherlands, 92(2):155-164, (2009).
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The concurrent determination of pesticidal and non-pesticidal organotin compounds in several water matrices, using a simultaneous in situ ethylation and liquid-liquid extraction followed by splitless injection mode capillary gas chromatography with pulsed flame photometric detection, is described. The speciation analysis of nine organotin compounds includes low molecular weight - low boiling (non-pesticidal) and high molecular weight - high boiling analytes (pesticidal) of significant environmental interest. The minimum time for sodium tetraethylborate alkylation, using mechanical agitation, is determined to be fifteen minutes in order to ensure the complete derivatization of the complete list of analytes. The utilization of a “hot needle” and a rapid injection rate is shown to be an efficacious means to eliminate “mass” or “needle” discrimination when determining the mixture of organotin compounds. Method detection limits are calculated to be in the low ng L-1 range. The final method is applied to various water samples; storm water from the Cincinnati area demonstrated low native levels of three of the organotin compounds.
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| JOURNAL |
A Mouse Model for Characterization of Gastrointestinal Colonization Rates Among Environmental Aeromonas Isolates |
05/01/2009
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LYE, D. J. A Mouse Model for Characterization of Gastrointestinal Colonization Rates Among Environmental Aeromonas Isolates. CURRENT MICROBIOLOGY. Springer, New York, NY, 58(5):454-458, (2009).
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The colonization rates of ten different environmental isolates of Aeromonas were determined using a novel mouse-streptomycin pre-treatment method. A novel streptomycin pre-treatment prepared animals with a transient alteration in colon flora that allowed colonization by Aeromonas which would not occur in the presence of normal competitive host bacteria. Colonization rates of Aeromonas salmonicida, Aeromonas enchelia, and Aeromonas allosaccharophila were low and occurred randomly with respect to concentrations of the dosage consumed by the animals. In contrast, Aeromonas hydrophila, Aeromonas veronii, and Aeromonas caviae exhibited relatively high rates of colonization of mouse colon tissues.
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| JOURNAL |
Solar Radiation Disinfection of Drinking Water at Temperate Latitudes: Inactivation Rates for An Optimized Reactor Configuration |
02/01/2009
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Davies, C. M., D. J. Roser, A. J. Feitz, AND N. ASHBOLT. Solar Radiation Disinfection of Drinking Water at Temperate Latitudes: Inactivation Rates for An Optimized Reactor Configuration. WATER RESEARCH. Elsevier Science Ltd, New York, NY, 43(3):643-652, (2009).
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Solar radiation-driven inactivation of bacteria, virus and protozoan pathogen models was quantified in simulated drinking water at a temperate latitude (34°S). The water was seeded with Enterococcus faecalis, Clostridium sporogenes spores, and P22 bacteriophage, each at ca 1 x 10,sup>5 mL-1, and exposed to natural sunlight in 30-L reaction vessels. Water temperature ranged from 17 to 39 °C during the experiments lasting up to 6 h. Dark controls showed little inactivation and so it was concluded that the inactivation observed was primarily driven by non-thermal processes. The optimised reactor design achieved S90 values (cumulative exposure required for 90% reduction) for the test microorganisms in the range 0.63–1.82 MJm-2of Global Solar Exposure (GSX) without the need for TiO2 as a catalyst. High turbidity (840–920 NTU) only reduced the S90 value by <40%. Further, when all S90 means were compared this decrease was not statistically significant (prob. > 0.05).
However, inactivation was significantly reduced for E. faecalis and P22 when the transmittance of UV wavelengths was attenuated by water with high colour (140 PtCo units) or a suboptimally transparent reactor lid (prob. < 0.05). S90 values were consistent with those
measured by other researchers (ca 1–10 MJm-2) for a range of waters and microorganisms .
Although temperatures required for SODIS type pasteurization were not produced, nonthermal inactivation alone appeared to offer a viable means for reliably disinfecting low colour source waters by greater than 4 orders of magnitude on sunny days at 34°S latitude.
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| JOURNAL |
Screening Tools to Estimate Mold Burdens in Homes |
01/01/2009
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VESPER, S. J., C. McKinstry, K. D. BRADHAM, P. Ashley, D. Cox, G. Dewalt, AND K. Lin. Screening Tools to Estimate Mold Burdens in Homes. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL MEDICINE. Lippincott Williams & Wilkins, Philadelphia, PA, 51(1):80-86, (2009).
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Objective: The objective of this study was to develop screening tools that could be used to estimate the mold burden in a home which would indicate whether more detailed testing might be useful. Methods: Previously, in the American Healthy Home Survey, a DNA-based method of analysis called mold specific quantitative PCR was used to measure 36 molds in standard protocol dust samples. This resulted in a national index called the Environmental Relative Moldiness Index (ERMI). In this current study, two possible screening methods were considered: use of the vacuum cleaner bag dust rather than the standard protocol dust samples and reducing the number of molds needed to be quantified resulting in the creation of a simpler mold burden scale. Results: Comparison of vacuum bag and standard dust samples from 157 of the same homes demonstrated that most molds had higher detection rates in vacuum bag dust compared to athe standard dust samples but the ERMI values were still related to each other. The second approach to simplifying the screening for mold burdens produced a correlated (ρ=0.80) index to the ERMI called the American Relative Moldiness Index (ARMI) which requires the analysis of only 12 species. Conclusions: Vacuum bag dust sample ERMI values were predictive in placing a home into the lower or upper 50% of homes on the ERMI scale. If it is not possible to obtain athe standard dust sample, the vacuum cleaner bag dust may be a useful screening tool for estimating mold burdens in homes. If the standard sample is available and a simpler screening test is sought to estimate the mold burden in homes, the ARMI scale might be useful.
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| PRESENTATION |
Peak Health and the Need for More Sustainable Urban Water Systems |
08/18/2009
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ASHBOLT, N. Peak Health and the Need for More Sustainable Urban Water Systems. Presented at World City Water Forum 2009, Incheon, SOUTH KOREA, August 18 - 21, 2009.
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Large centralized urban water services in developed countries like the USA still provide significant environmental impact via loss of ecological water services, energy use, loss of nutrients from agricultural production, and eutrophication issues. Current climate models predict that many regions will generally be increasingly more water stressed as well as prone to intense storm events, further exacerbating the negative effects of centralized water services. As a consequence of many interacting factors based around energy/water use and social inequity, Peak Health may have already been reached in the USA, with life expectancies equal to that of Cuba (75 years). From a global perspective, rapidly developing regions, most of which are in water scarce regions, make water-based sanitation unsustainable if not impractical. Hence there is a need to rethink how water services can be obtained for the health of developed and developing regions by lowering our environmental footprint as well as empowering individuals/communities to control their water/sanitation services in a health-promoting environment. Examples include net energy production from organic components along with nutrients returned to agriculture, particularly phosphorus that has known stores of available rock phosphate to only last 60-150 years. From a public health perspective, aging water mains and their vulnerability to intrusions by fecally-contaminated waters is a rising issue; all the more reason to consider an alternative approach to water distribution and handling of associated wastewater streams rather than rebuilding more of the same problem. Most interesting is that the single largest cause of waterborne illness identified in the US (legionellosis) is not of fecal origin, nor currently regulated in most parts of the world. Legionellosis is due to the growth of a pathogen (Legionella pneumophila), which may largely be an in-premise (building) issue rather than the distribution system per se. Hence Legionella and other similar indigenous pathogens that grow in pipe biofilms are not necessarily the responsibility of the distribution system provider. As we move to greater reliance on reclaimed waters, fit-for-purpose, the long-term ramifications of fecal and indigenous pathogen issues should be considered within a broader sustainability assessment if we are to further improve public health. A framework for a way forward is described.
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| PRESENTATION |
Analysis of Arsenicals and Their Sulfur Analogs Using Hplc With Collision Cell ICP-MS and Esi-MS |
06/07/2009
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KUBACHKA, K., C. GALLAWA, P. A. CREED, J. T. CREED, M. J. KOHAN, K. HERBIN-DAVIS, AND D. J. THOMAS. Analysis of Arsenicals and Their Sulfur Analogs Using Hplc With Collision Cell ICP-MS and Esi-MS. Presented at International Symposium on Metallomics, Covington, KY, June 07 - 13, 2009.
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Recent metabolic and exposure assessment studies have found sulfur analogs (thioarsenicals) of common oxoarsenicals in environmental and biological systems. The occurrence of thioarsenicals raises questions regarding their origin and transport, and their roles in metabolism of arsenic. Definitive answers to these questions require speciation based methods that can separate and quantify oxo- and thioarsenicals in complex mixtures. Various LC methods are often necessary to separate such complex mixtures. Because thioarsenicals are often present in samples at low ng/g concentrations, elemental detection via ICP-MS is most commonly used for quantitation. Additionally, LC-ESI-MS/MS techniques have proven valuable for complementary verification of standards and confirmation of suspect peaks, because many arsenic standards and their sulfur analogs are not commercially available.
An emerging area of arsenic metabolic research focuses on understanding of origin of thioarsenicals that are detected as excreted metabolites in many higher organisms, including humans. We have used an in vitro assay to examine the role of the anaerobic microbiota of mouse cecum in the metabolism of thio- and oxoarsenicals1-3. These studies have shown that there is considerable preabsorption metabolism of these arsenicals that is mediated by the anaerobic microbiota of mouse cecum. This presentation will summarize results from our studies on the conversion of dimethylarsinic acid and trimethylarsine oxide with an emphasis on utilizing ESI-MS/MS for identification. In addition, preliminary research on the role of the anaerobic microbiota in conversion of inorganic arsenic and monomethylarsonic acid to thioarsenicals will be presented.
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| PRESENTATION |
Population Based Exposure Assessment of Bioaccessible Arsenic in Carrots |
06/07/2009
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Yathavakilla, S. K., A. R. Young, S. E. Lenhof, M. Mantha, C. GALLAWA, P. A. CREED, J. XUE, AND J. T. CREED. Population Based Exposure Assessment of Bioaccessible Arsenic in Carrots. Presented at International Symposium on Mettalomics, Covington, KY, June 07 - 13, 2009.
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The two predominant arsenic exposure routes are food and water. Estimating the risk from dietary exposures is complicated, owing to the chemical form dependent toxicity of arsenic and the diversity of arsenicals present in dietary matrices. Two aspects of assessing dietary exposure risk, which are often overlooked in speciation analysis, are producing a bioaccessibility estimate and the need to collect samples which support a population based exposure assessment. In an attempt to address these shortcomings, the authors have applied an enzymatic extraction to carrots which were collected from various geographical locations based on harvest demographics. The extracts were speciated by IC-ICP-MS utilizing collision cell technology to address the high chloride concentrations characteristic of in-vitro assays designed to mimic the gastrointestinal tract. The distribution of the inorganic arsenic concentration in carrots was then combined with the distribution associated with carrot consumption in the US using a probabilistic based model. The model randomly selects an arsenic concentration and consumption rate from the distributions and through an iterative process generates a population based exposure profile for arsenic in carrots. This approach to population based exposure assessment is especially applicable to arsenic because over 90% of the exposure can be attributed to 4-5 commonly consumed foods. This limited number of foods produces a relatively robust estimate without having to independently estimate the contribution of all other foods to the cumulative exposure. This presentation will discuss the limitations associated with the IC-ICP-MS approach and outline the application of the model to this type of exposure assessment.
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| PRESENTATION |
Role of Waterborne Pathogens in the Food Supply Chain: Implications to Risk Management With Local and Global Perspectives |
06/06/2009
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ASHBOLT, N. Role of Waterborne Pathogens in the Food Supply Chain: Implications to Risk Management With Local and Global Perspectives. Presented at IFT Conference, Anaheim, CA, June 06 - 09, 2009.
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Microbial risk assessment (MRA) in the food industry is
used to support HACCP – which largely focuses on
bacterial pathogen control in processing foodstuffs
Potential role of microbially-contaminated water used in
food production is not as well understood
Emergence of Quantitative MRA as a tool for assessing
& informing waterborne pathogen risks internationally
WHO: water safety plans (2004), wastewater reuse (2006)
Primary point of this paper is to highlight
potential risks from water in food production
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| PRESENTATION |
Diversity of Free-Living Amoebae in a Dual Distribution (Potable and Recycled) Water System |
06/01/2009
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Thomas, J., M. Storey, R. Stuetz, S. Kjelleberg, AND N. ASHBOLT. Diversity of Free-Living Amoebae in a Dual Distribution (Potable and Recycled) Water System. Presented at IWA Health-Related Water Microbiology Biannual Conference, Naxos, GREECE, June 01 - 04, 2009.
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Free-living amoebae are known to facilitate the growth of water associated pathogens. This study, for the first time, explored the diversity of free-living amoebae in a dual distribution (potable and recycled) water system in Rouse Hill NSW, Australia. Water and biofilm samples were taken from the tertiary recycled water treatment plant and from within the two distribution systems (using a Modified Robbins Device). Amoebae were not detected entering the distribution systems from the tertiary recycled water treatment plant over a 6 week sampling period. However, amoebae were isolated within the recycled water distribution system (0.1
amoebae/ml). Furthermore, amoebae were isolated from within the potable water distribution system (0.2 amoebae/ml). Chlorine concentrations appear to explain the different amoebae numbers. More research is required to determine the relationship between these
free-living amoebae and water associated pathogens within this water distribution system.
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| PRESENTATION |
Molecular-Based Detection Systems for Cryptosporidium Oocysts |
05/20/2009
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VILLEGAS, E. Molecular-Based Detection Systems for Cryptosporidium Oocysts. Presented at 2009 USEPA STAR Grants Workshop on Innovative Approaches to Detecting Microorganisms and Cyanotoxins in Water, Philadelphia, PA, May 20 - 21, 2009.
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The presentation describes on-going studies in collaboration with US EPA Region 2, 3, and the CDC on identifying sources of Cryptosporidium oocyst contamination in source waters using conventional and real-time PCR approaches.
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| PRESENTATION |
The Virtual Environmental Microbiology Center a Social Network for Enhanced Communication Between Water Researchers and Policy Makers |
05/17/2009
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Mistry, J. H., F. S. HAUCHMAN, M. R. RODGERS, AND N. ASHBOLT. The Virtual Environmental Microbiology Center a Social Network for Enhanced Communication Between Water Researchers and Policy Makers. Presented at American Society for Microbiology 109th General Meeting, Philadelphia, PA, May 17 - 21, 2009.
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Effective communication within and between organizations involved in research and policy making activities is essential. Sharing information across organizational and geographic boundaries can also facilitate coordination and collaboration, promote a better understanding of technical and policy issues, and avoid duplication of effort. To enhance communication within the environmental microbiology community, the U.S. Environmental Protection Agency (EPA) developed the Environmental Science Connector (ESC) (http://portal.epa.gov/ESC ), a web-based communication tool that can bring together people with diverse interests and expertise to share information on a wide range of environmental microbiology topics. It also provides a convenient means for EPA scientists to manage projects, interact with project collaborators through message boards, and participate in real-time web based seminars. The ESC is being used to bring the environmental microbiology community together to share information on a variety of topics. Using the ESC as a platform, a virtual seminar series has been launched to allow subject matter experts in the fields of environmental microbiology and microbial ecology to openly discuss state-of-the-science research topics with network members, further fostering a sense of community and exchange of ideas. In addition, the ESC is providing a focal point for intra-governmental communication and collaboration on several specific research topics, including sample preparation for waterborne pathogens, the development of graywater guidance and microbial risk assessment.
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| PRESENTATION |
Utilization of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (Maldi-MS) to Identify Environmental Strains of Mycobacterium Complex |
05/17/2009
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DONOHUE, M. J., J. H. Mistry, AND S. L. PFALLER. Utilization of Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (Maldi-MS) to Identify Environmental Strains of Mycobacterium Complex. Presented at American Society for Microbiology Annual Meeting, Philadelphia, PA, May 17 - 21, 2009.
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Species within the Mycobacterium avium Complex (MAC) group
are found to be both prevalent and persistent in drinking water
distribution systems. The MAC is composed of two predominant
species: M. avium and M. intracellulare. These species have the
ability to survive drinking water disinfection treatments and to
thrive in distribution systems via biofilms. For these reasons, the
US Environmental Protection Agency (EPA) has listed MAC on the
Contaminant Candidate List (CCL) as a potential contaminant that
may require regulation if it is proven to have a significant health
burden to the public.
A major challenge associated with environmental MAC isolates is
the ability to rapidly identify the isolate to the species level. The
tools currently available for identification/speciation can be
time-consuming, as well as give ambiguous results due to their
inability to clearly differentiate species. The purpose of this study
was to evaluate Matrix-Assisted Laser Desorption/Ionization Mass
Spectrometry (MALDI-MS) as a means to rapidly speciate MAC
environmental isolates.
The research presented will demonstrate the use of MALDI-MS to
speciate environmental isolates based on their m/z signature.
Initially, a database of m/z signatures was constructed using MAC
reference and type strains. Next, m/z signatures from
environmental isolates were compared to the database of known
m/z signatures. Additionally, DNA sequence analyses of genes
coded for the heat shock protein 65 (hsp65), RNA polymerase
subunit B (rpoB), and 16S rRNA were used to validate the
MALDI-MS determination.
MALDI-MS analysis is ideal for the identification/speciation of
environmental isolates. This is primarily due to the minimal
sample preparation involved (i.e., the ability to go from culture
plate directly to analysis), as well as the short analysis time (<2
min) before a determination can be made. These traits make
MALDI-MS a powerful tool suited for environmental monitoring and
identification of microbial hazards in drinking water.
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| PRESENTATION |
U.S. Environmental Protection Agency and Emerging Contaminants |
05/13/2009
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GLASSMEYER, S. U.S. Environmental Protection Agency and Emerging Contaminants. Presented at New Jersey institute of Technology Workshop, Newark, NJ, May 13, 2009.
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In the past decade, the scientific community and general public have become increasingly aware of the potential for the presence of unregulated, and generally unmonitored contaminants, found at low concentrations (sub-ug/L) in surface, ground and drinking water. The most common pathway for the introduction of these chemicals is from an upstream direct discharge of wastewater effluent. In the US, there are more than two dozen communities that draw their drinking water from streams that consist of more than 50 % wastewater during low flow conditions. The US Geological Survey (USGS) and US Environmental Protection Agency (USEPA) have been working on a series of collaborative research projects to determine the identity of chemicals that are commonly present in wastewater effluent, the persistence of these chemicals in surface and ground waters, the removal of these chemicals during drinking water treatment, the formation of by-products during their chlorination and the presence of these chemicals in finished drinking water. In effluents collected at eleven wastewater treatment plants (WWTPs) across the US, 72 out of 110 monitored chemicals were detected at least once, documenting incomplete removal during wastewater treatment. Downstream of the WWTPs, the chemicals exhibited varying environmental persistence. To determine which wastewater chemicals persist through drinking water treatment, a follow-up study examined source and finished waters for nine drinking water treatment plants from across the United States known to be impacted by wastewater. All water samples were analyzed for 84 different emerging contaminants, including 24 pharmaceuticals. The sample collection was designed to account for residence time within the plant in order to match waters before and after treatment. The investigated utilities used varying source waters (surface or ground water), disinfectants (chlorine, chlorine dioxide, chloramine, ozone or UV), and produced different volumes of treated water per day (2.3 to 200 mgd). Thirty-five chemicals were detected at least once, with 28 chemicals detected in the source waters and 23 chemicals detected in the finished waters. The greatest number of chemicals detected in a single source water sample was 15; the greatest number detected in a single finished water was 11. In companion laboratory studies on the effects of chlorination, eight of the 14 chemicals investigated were oxidized by the disinfectant, two of which were at least partially chlorinated. Taken as a whole, these studies demonstrate that to understand the comprehensive environmental impact of emerging contaminants, their persistence, removal efficiencies during waste and drinking water treatment, as well as the potential for by-product formation, must be known.
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| PRESENTATION |
Surveillance Systems for Waterborne Protozoa: Beyond Method 1623 |
04/24/2009
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VILLEGAS, E. Surveillance Systems for Waterborne Protozoa: Beyond Method 1623. Presented at Greater Cincinnati Water Works Science Advisory Board Meeting, Cincinnati, OH, April 24, 2009.
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1. Brief introduction to waterborne Cryptosporidium and Giardia
Historical perspective on detecting Cryptosporidium and Giardia
Current detection methodologies
2. US EPA’s waterborne protozoan research program
Building a “Protozoan Detection Toolbox”
3. Perspectives on the future of the “Protozoan Detection Toolbox”
Future directions
Factors to consider for developing a pathogen specific detection method
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| PRESENTATION |
Qpcr Determined Fecal Indicator Bacterial Densities in Marine Waters from Two Recreational Beaches |
04/20/2009
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CHERN, E. C., K. P. Brenner, L. J. WYMER, AND R. A. HAUGLAND. Qpcr Determined Fecal Indicator Bacterial Densities in Marine Waters from Two Recreational Beaches. Presented at EPA National Beaches Conference 2009, Huntington Beach, CA, April 20 - 22, 2009.
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The use of real-time qPCR to determine fecal indicator bacteria (FIB) densities is currently being investigated by the U.S. EPA. The present recreational water quality guidelines, based on culturable FIB, prevent same day determinations of water quality whereas results from the qPCR method can be available within several hours. Epidemiological studies at POTW-impacted freshwater beaches have shown a strong correlation between qPCR determined Enterococcus densities and swimming-related illness rates. This study provides an initial assessment of qPCR estimated Enterococcus, Bacteroidales, E. coli and Clostridium densities in marine water from two recreational beaches sampled over one summer. The estimated geometric mean cell densities per 100 ml of marine water from both beaches across sampling visits were 3.28 x 10 1, 1.71 x 103, 7.37 x 102, and 9.26 x 102 for Enterococcus, Bacteroidales, E. coli and Clostridium, respectively. These cell equivalent density estimates, determined using whole cell calibrator samples by a comparative cycle threshold (CT) approach, did not correspond with the relative target sequence density estimates of the different FIB in the samples which gave geometric means of 1.28 x 103, 2.35 x 104, 3.04 x 102, and 1.03 x 104 for Enterococcus, Bacteroidales, E. coli and Clostridium, respectively. This discrepancy was determined to be attributable to differences in recovery of target sequences from cells of the different organisms. QPCR analyses using whole cell calibrator samples provides a simple approach for comparing both total cell and target sequence density estimates of different FIB groups in water samples.
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| PRESENTATION |
Comparison of Enterococcus Qpcr Analysis Results from Fresh and Marine Water Samples on Two Real-Time Instruments |
04/20/2009
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HAUGLAND, R. A., M. VARMA, R. OSHIRO, J. Parr, AND M. Doolittle. Comparison of Enterococcus Qpcr Analysis Results from Fresh and Marine Water Samples on Two Real-Time Instruments. Presented at National Beaches Conference 2009, Huntington Beach, CA, April 20 - 22, 2009.
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EPA is currently considering a quantitative polymerase chain reaction (qPCR) method, targeting Enterococcus spp., for beach monitoring.
Improvements in the method’s cost-effectiveness may be realized by the use of newer instrumentation such as the Applied Biosystems
StepOneTM and StepOnePlusTM series instruments that can retail for under $20 K and provide 48 or 96 sample analysis capacity. In this study
we compared the results obtained on a StepOnePlusTM 96 well instrument with those obtained on the Cepheid Smart Cycler® which has been
the primary source of the method’s results to date. Analyses were performed simultaneously on DNA extracts from multiple, replicate filter
retentates of 12 marine and 12 freshwater samples from diverse locations using study and data analysis designs from EPA's microbial
alternate test procedure protocol. Precision among log10 target sequence copy (TSC) estimates in the samples from the two instruments were
compared with no significant difference (p > .05) based on the one-way ANOVA of Levene's Test for Homogeneity of Variance. Three–way
ANOVA with fixed factors: instrument, matrix, instrument*matrix; and random factors: sample (nested in matrix) and inst*sample (nested in
matrix) was used to compare the mean log10 TSC estimates with no significant difference seen between the instruments (p > .05). Given the
wide variety of qPCR instruments that are already available and the likelihood that additional advances will occur in instrument technology,
this study may provide a useful model for the design and implementation of additional comparative studies in the future.
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| PRESENTATION |
What Is the Relative Health Risk to Swimmers from California Seagull Feces Compared to Bather Shedders? |
04/20/2009
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Schoen, M. AND N. ASHBOLT. What Is the Relative Health Risk to Swimmers from California Seagull Feces Compared to Bather Shedders? Presented at National Beach Conference, Huntington Beach, CA, April 20 - 22, 2009.
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Estimated infection risks to swimmers from California seagull and bather sources of fecal contamination at a beach in Southern California were compared using quantitative microbial risk assessment (QMRA). The risk to swimmers of gastro-intestinal infections was estimated from Campylobacter jejuni, Cryptosporidium hominis, and Norovirus from human bathers and Campylobacter jejuni from Californian seagulls over the observed range of surfzone enterococci (ENT) concentration during normal summer conditions at Dohney Beach. A beta-Poisson dose-response model was utilized with pathogen specific parameters to calculate the probability of infection using Monte Carlo analysis of the uncertain input variables. Overall, the individual risks from C. jejuni and Norovirus were greater than that from C. hominis. Specific predictions of risk remain uncertain due to large uncertainty in model parameters; particularly the proportion of Campylobacter strains that are human infectious. If the proportion of infectious strains from gulls is low, near 0.01, then human infection risk from accidental ingestion of bathing water containing gull feces is only greater than the risk from bather shedders when gull fecal matter in the bathing waters exceeds that from humans by more than 20 times; that reduces to four times should the proportion of infectious C. jejuni gull strains be 0.05. The best estimate model results indicated that gull fecal-derived enterococci counts contribute less of a health threat to swimmers than human sources; however there remains large uncertainty in prediction due to the remaining uncertainty in human infectious campylobacter species in gull feces, their unknown environmental persistence and the level of bather shedding of human pathogens.
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| PRESENTATION |
Emerging Contaminants in the Drinking Water Cycle. |
04/15/2009
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GLASSMEYER, S. Emerging Contaminants in the Drinking Water Cycle. Presented at Region 3 Emerging Contaminants Webcast, The Web, Newark, NJ, April 15, 2009.
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In the past decade, the scientific community and general public have become increasingly aware of the potential for the presence of unregulated, and generally unmonitored contaminants, found at low concentrations (sub-g/L) in surface, ground and drinking water. The most common pathway for the introduction of these chemicals is from an upstream direct discharge of wastewater effluent. In the US, there are more than two dozen communities that draw their drinking water from streams that consist of more than 50 % wastewater during low flow conditions. The US Geological Survey (USGS) and US Environmental Protection Agency (USEPA) have been working on a series of collaborative research projects to determine the identity of chemicals that are commonly present in wastewater effluent, the persistence of these chemicals in surface and ground waters, the removal of these chemicals during drinking water treatment, the formation of by-products during their chlorination and the presence of these chemicals in finished drinking water. In effluents collected at eleven wastewater treatment plants (WWTPs) across the US, 72 out of 110 monitored chemicals were detected at least once, documenting incomplete removal during wastewater treatment. Downstream of the WWTPs, the chemicals exhibited varying environmental persistence. To determine which wastewater chemicals persist through drinking water treatment, a follow-up study examined source and finished waters for nine drinking water treatment plants from across the United States known to be impacted by wastewater. All water samples were analyzed for 84 different emerging contaminants, including 24 pharmaceuticals. The sample collection was designed to account for residence time within the plant in order to match waters before and after treatment. The investigated utilities used varying source waters (surface or ground water), disinfectants (chlorine, chlorine dioxide, chloramine, ozone or UV), and produced different volumes of treated water per day (2.3 to 200 mgd). Thirty-five chemicals were detected at least once, with 28 chemicals detected in the source waters and 23 chemicals detected in the finished waters. The greatest number of chemicals detected in a single source water sample was 15; the greatest number detected in a single finished water was 11. In companion laboratory studies on the effects of chlorination, eight of the 14 chemicals investigated were oxidized by the disinfectant, two of which were at least partially chlorinated. Taken as a whole, these studies demonstrate that to understand the comprehensive environmental impact of emerging contaminants, their persistence, removal efficiencies during waste and drinking water treatment, as well as the potential for by-product formation, must be known.
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| PRESENTATION |
Postmodern Urban Infrastructure Pathogens and Other Scum Associates |
03/11/2009
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ASHBOLT, N. Postmodern Urban Infrastructure Pathogens and Other Scum Associates. Presented at Johns Hopkins, Washington, DC, March 11, 2009.
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| Abstract:
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To be presented at Johns Hopkins, Washington, DC, March 11, 2009
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| PRESENTATION |
An Investigation of Bioaccessibility of Arsenic in Rice Using Ic-ICP-MS |
03/08/2009
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Young, A. R., H. Trenary, S. K. Yathavakilla, P. A. CREED, J. T. CREED, AND J. XUE. An Investigation of Bioaccessibility of Arsenic in Rice Using Ic-ICP-MS. Presented at 2009 Pittcon , Chicago, IL, March 08 - 13, 2009.
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Arsenic exposure occurs mainly through drinking water and food; therefore, both aspects should be incorporated into any aggregate exposure assessment. Drinking water exposures are predominately inorganic arsenic while dietary exposures are made up of a diverse set of arsenicals with widely varying toxicities.
Rice collected throughout the world has been shown to be relatively high in total arsenic. In fact, the FDA’s market basket survey supports this observation and for this reason rice is a target food group for dietary speciation studies. Arsenic speciation has been conducted on rice grown in endemic areas and in the U.S. In these studies, inorganic arsenic and DMA are the predominant arsenicals found in rice; however, the variation associated with the distribution of these two arsenicals is far from a constant. Therefore, a quantitative exposure assessment
for rice needs to incorporate not only species specific information, but also the variation associated with the distribution of the arsenicals, in order to improve the exposure risk estimate for rice.
Another factor which needs to be considered in the exposure assessment is the biologically relevant arsenic dose associated with rice consumption. Information on bioaccessible arsenic, the fraction of analyte which is solubilized by the gastrointestinal (GI) tract, could provide a means to estimating the biologically relevant dose. Ideally, this bioaccessibility term would also include the GI tract induced biotransformations associated with the ingested arsenicals. Currently, the species specific rice data are mainly comprised of chemically based extractions.
These extractions are relatively simple and quantitative, but it is not known how accurately these extractions correlate with bioaccessibility.
Therefore, an assay that can estimate the species specific bioaccessibility and capture the biotransformation in the GI tract should improve the exposure estimate. An application of this type of assay should provide data essential to estimating biologically relevant exposures in target foods. This presentation will attempt to estimate the bioaccessible fraction associated with U.S. consumed rice using a synthetic gastrointestinal extraction technique prior to speciation via ICICP-MS. Finally, the potential for biotransformation of the extracted arsenicals will be evaluated by using an in vitro technique in which a gastrointestinally extracted rice sample is incubated in the cecum content of a mouse.
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| PRESENTATION |
Rapid Methods for the Detection of General Fecal Indicators |
02/11/2009
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HAUGLAND, R. A. AND K. OSHIMA. Rapid Methods for the Detection of General Fecal Indicators. Presented at Gulf of Mexico Alliance, Microbial Source Tracking (MST) & Pathogens Detection Workshop, St. Petersburg, FL, February 11, 2009.
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Specified that EPA should develop:
appropriate and effective indicators for improving detection in a timely manner of pathogens in coastal waters
appropriate, accurate, expeditious and cost-effective methods for the timely detection of pathogens in coastal waters
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| PRESENTATION |
Surveillance Systems for Waterborne Cryptosporidium: US EPA Method 1523 and Beyond |
02/08/2009
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VILLEGAS, E. Surveillance Systems for Waterborne Cryptosporidium: US EPA Method 1523 and Beyond. Presented at 2009 USDA-CSREES National Water Conference, St. Louis, MO, February 08 - 12, 2009.
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Waterborne cryptosporidiosis remains a significant public health concern in countries around the world. Many species and genotypes of Cryptosporidium contaminate drinking water sources, but C. parvum and C. hominis remain the two predominant species known to cause waterborne disease outbreaks in humans. To improve human health and reduce risks posed by these pathogens, the US EPA promulgated the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule). This rule requires drinking water utilities to monitor for Cryptosporidium oocysts in their source waters using US EPA Method 1622 or 1623. These methods are designed to enumerate oocysts by microscopy and although very useful in determining concentration levels of Cryptosporidium oocysts in various drinking water sources throughout US, the methods are time consuming, labor intensive and cannot distinguish animal from human specific species or determine if the oocysts are infectious to humans. Because many Cryptosporidium spp. oocysts are morphologically similar and can contaminate drinking water supplies, the development of more specific detection and typing approaches for this parasite are essential to better understand the impact of this protozoan in source waters. The data generated by these methods will provide additional information that will be useful for future source water management strategies and for human health risk assessments related to Cryptosporidium oocyst contamination. Current research activities focused on developing new and more rapid molecular-based approaches (e.g., quantitative real-time PCR, microarrays, etc.) that can detect and determine the infectious potential of oocysts will be described. Advantages and inherent limitations of these approaches and their potential application(s) as alternative methods to current Cryptosporidium surveillance systems will be discussed.
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