I

1
I Exposure Assessment

• Charles Gerba - UA
• Chris Choi UA
• Mark Nicas UCB
• Paul Kiem NAU
• Syed Hashsham - MSU

2
Group 1 Exposure
3
Overall Objectives

• Development of new BAC surrogates for application
  in methods assessment and transport and fate
  modeling efforts.
• Validation of detection methods for microbial
  risk assessment.
• Development of fate and transport models for BAC
  on fomites.
• Development of fate and transport models for BAC
  in water systems.
• Development and validation of a discrete-time
  Markov chain model for airborne BAC within a
  room.
• Measure the re-suspension of particle-associated
  BAC in a test room or chamber
• Determine the particle size distribution of
  respiratory aerosol

4
Year 1

• Assessment of coliphage surrogates
• Characterization of PRD1/MS-2 as surrogates
• Assessment of fomite sampling protocols
• Development of k values (decay rates)
• Anthrax detection methods sensitivity
• Identification of anthrax surrogates
• Improvement to distribution system transport
  model
• Improvement to Markov Chain model

5
Assessment of Phage Surrogates

• PRD-1 and MS-2 being assessed (most extensively
  used phage models)
• PRD-1, which has been extensively used previously
  as a model appears to actually be P-22
• Primers developed and assess for PRD-1
  application
• Sampling methods and survival on various fomites
  assessed

6
Variability and Associated Recovery Methods from
Fomites
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Comparison of Sampling Method and Survival of
Coliphage MS-2 on Fomites
Surface Method T90 (days) T99 (days)
Cotton Vortex 10.6 21.2
Laminar Vortex 16.5 33.0
Laminar Swab 12.0 23.9
Laminar Fellowes 11.5 23.0
Steel Vortex 5.6 11.1
Steel Swab 5.1 10.1
Steel Fellowes 4.4 8.9
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Decay Rate on Fomites (K)

• To be useful in model predictive models on the
  fate of agents of concern information on their
  decay on fomites needs to be normalized from
  various studies published in the literature.
• The existing literature was reviewed and data on
  agent decay was normalized against environmental
  conditions
• This data can now be used in models to predict
  survival of these agents on fomites. It was found
  that enteric viruses survive for days to months
  on surfaces compared to hours to days for
  respiratory viruses.

9
Respiratory virus inactivation rates (K)
10
Limit of Detection Methods for Anthrax in Water

• Real time polymerase chain reaction (PCR),
  conventional PCR, and selected antibody based and
  chemiluminiscence assays are among the most
  sensitive detection methods is one of the main
  accomplishments this year.
• A similar analysis for air and soil is also
  complete with similar conclusions.

11
Distribution of detection limit various methods
available to detect Anthrax in water
12
Quantum dots as surrogates of bacterial
pathogens
(Only selected characteristics)
EviFluor antibodies or protein conjugated EviTag Approx. hydrodynamic diameter 25nm Bio-available DNA strands can be attached
EviTag Quantum dots with PEG lipid surface coating coupled to amine terminal groups Approx. hydrodynamic diameter 25nm Bio-available DNA strands can be attached
EviDotCdSe/ZnS Core-shell Approx diameter 2-5 nm
Non bio-available
Fluorescence varies with size of QD (2nm-5nm) EviTag with green fluorescence (diameter 25nm, emission 520nm) was used
13
Comet Assay
DNA Break is taken as an indication of
genotoxicity
ALKALINE ELECTROPHORESIS
Normal Human Lymphocytes
STAINING (EtBr)
Lymphocyte Showing DNA Damage
14
Effect of quantum dots on human lymphocytes DNA
damage by Comet assay


plt0.05,plt0.01, plt0.001



Values mean SD Cell viability in all the
treatment concentrations gt90 Positive control
(EMS 2mM)- Tail moment gt350
15
Distribution System Fate and Transport Modeling

• Fate Transport in Water System
• Investing water quality models at intersections
  of pressurized pipe systems
• Experimental verifications have been carried out
  at the Water Village.
• Creating several scenarios in order to generate
  training and testing data required for a
  back-propagation Artificial Neural Network (ANN)
  with six input (water demands) and six output
  (average concentration) units.

16
Distribution System Modeling
RISK ASSESSMENT

• EPANET-based Simulation
• HD Model
• - WQ Model

ANN-based Prediction Models
Indicator Microorganisms
Experimental Validation using Water-Distribution
Networks at the Water Village
17
Key Components of a Typical Drinking Water System
Their Vulnerabilities
18
Water Systems Microbiology Laboratory
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Water Distribution Systems Laboratory
20
Mixing patterns along the interface
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Corresponding Risk Microbial Risk Assessment
Consequences
22
Distribution System Fate and Transport Modeling
- Contributions

• Corrections in EPANET model and further
  calibration
• Construction of distribution system network and
  initial model testing

23
Modeling Airborne Fate and Transport of Agents of
Concern

• Refinement of a simple Markov Chain Model
• Development method for incorporating information
  on air velocity and turbulent intensity values
• Validate Markov chain particle model via
  published data
• Construct test chamber

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Year-1 Publications

• Boone, S. A. and C. P. Gerba 2006. The
  significance of fomites in the spread of
  respiratory and gastrointestinal disease. Applied
  and Environmental Microbiology, In Press.
• Romero-Gomez, P., C. Y. Choi, B. van Bloemen
  Waanders, and S. McKenna, Transport Phenomena at
  Intersections of Pressurized Pipe Systems, 2006,
  8th Annual Water Distribution Systems Analysis
  Symposium, Cincinnati, OH.
• Alok K. Pandey, Amanda B. Herzog, Joan B. Rose,
  Syed A. Hashsham. Potential of Quantum Dots as
  Surrogates for Microbial Pathogens and Evaluation
  of Their Genotoxicity. 107th General Meeting of
  the American Society for Microbiology, Toronto,
  Canada, May 21-25, 2007.
• Amanda B. Herzog, Alok Pandey, Tomoyuki Shibata,
  Joan B. Rose, and Syed A. Hashsham. Implications
  of Detection Limit of Various Methods of Bacillus
  anthracis in Computing Risk to Human Health.
  107th General Meeting of the American Society for
  Microbiology, Toronto, Canada, May 21-25, 2007.

26
Year 2

• Determine attenuation rates of various Bacillus
  species under natural conditions. B. anthracis,
  B. thuringiensis, B. globigii
• compare qPCR and Cultivation for DL for P22 from
  fomites, from air and from water.
• Conduct aerosol release experiments to assess
  Markov chain particle model

27
Year 2

• Criteria for Surrogates document
• Decay constants (K values) for BAC in water,
  fomites, aerosols
• Selection and assessment of a surrogate for B.
  anthracis
• Development of an algorithm for detection limit
  and risk
• Assessment of quantum dots as a surrogate

28
Year 2

• Conduct dispersion studies of MS-2/PRD-1
  surrogates in water distribution system at the
  Water Village to aid model development
• Establish prediction models using artificial
  neural networks based on experimental data and
  EPAnet

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Anticipated Products

• Improved standard operating procedure for
  sampling
• Set of methods criteria and algorithms for
  addressing the interpretation of a negative
• Models for air/surface/hand risks
• Models for microbial transport in water
  distribution systems