Grantee Research Project Results
2009 Progress Report: Measures of Distribution System Water Quality and Their Relation to Health Outcomes in Atlanta
EPA Grant Number: R834250Title: Measures of Distribution System Water Quality and Their Relation to Health Outcomes in Atlanta
Investigators: Moe, Christine L. , Uber, Jim , Klein, Mitchel , Tolbert, Paige , Tinker, Sarah , Hooper, Stuart
Current Investigators: Moe, Christine L. , Sarnat, Stefanie Ebelt , Kirby, Amy , Levy, Karen , Klein, Mitchel , Tolbert, Paige
Institution: Rollins School of Public Health, Emory University , University of Cincinnati
Current Institution: Rollins School of Public Health, Emory University
EPA Project Officer: Page, Angela
Project Period: July 1, 2009 through June 30, 2012 (Extended to June 30, 2014)
Project Period Covered by this Report: August 1, 2009 through July 31,2010
Project Amount: $599,756
RFA: Innovative and Integrative Approaches for Advancing Public Health Protection Through Water Infrastructure Sustainability (2008) RFA Text | Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , Sustainable and Healthy Communities , Water
Objective:
Year 1 Goals
In the first year of this grant, our major goals have been to:
- Select a utility for which a distribution system vulnerability assessment for pathogen contamination will be conducted and collect necessary data.
- Collect new 2004-2009 data from distribution systems previously assessed in EPA Grant R831629 “Drinking Water Quality and Emergency Visits for Gastroenteritis in Atlanta”
- Initiate distribution system vulnerability assessment of selected utility.
- Perform analysis for Aim A: To refine the previously-conducted analyses assessing the association between rates of ED visits for GI illness and estimated residence times of drinking water serving the study area of two utilities, using geocoded patient address data to identify the closest node in the distribution system.
- Compile emergency department visit data collected through 2009 into an analytical dataset.
- Initiate automated monitoring and sampling (AMS) unit monitoring of water quality characteristics in Emory laboratory and develop AMS field monitoring protocol.
Progress Summary:
Progress Toward Year 1 Goals
- After meeting with officials at both Cobb County Marietta Water Authority (CCMWA) and the City of Atlanta (COA), we have selected the COA drinking water distribution system for the vulnerability assessment because we find this system to be more representative of distribution systems in most major U.S. cities than CCMWA. We have developed a data sharing agreement with the COA to conduct this research.
- We are in the process of obtaining 2004-2009 data from COA and CCMWA. Co-investigator James Uber has initiated the vulnerability assessment.
- We currently are compiling an analytical dataset and performing quality assurance procedures for the Aim A analysis and expect to produce a manuscript in the coming year.
- We have requested emergency department visits data from the Georgia Hospital Association, and we expect to have an analytical dataset prepared by November 2010.
- The AMS unit currently is set up and running in our lab.
The plan outlined in our Quality Assurance Plan is being followed. Secondary data are being rigorously reviewed to ensure quality. Data processes including joining and merging datasets are being replicated to ensure that the methods will be consistent between data analyzed in the previous study (1993-2004) and the current study (2005-2009) to allow for comparison.
Results to Date
We have primarily focused on data collection and cleaning in this period. We have produced some preliminary descriptive statistics for research Aim A: to refine the previously conducted analyses assessing the association between rates of emergency department (ED) visits for gastrointestinal (GI) illness and estimated residence times of drinking water using geocoded patient address data to identify the closest node in the distribution system. We are still constructing the analytical dataset, so no preliminary analyses regarding associations have yet been conducted. In addition, work progressed on the simulation modeling framework required for the vulnerability analysis that supports Aim E. This framework will use network water quality simulations to predict the time history of pathogen concentrations at consumer taps, under specific assumptions about the means by which pathogens may enter the distribution system: 1) breakthrough at the treatment source; 2) low pressure-induced intrusion through leaks; 3) pipe breaks and repairs; and 4) combinations of the above. The predicted statistical characterization of pathogen concentrations, as a function of location, will be used as the independent variable in an updated analysis of associations with ED visits for GI illness in the study area (i.e., replicating the role that water age played in the previously published analyses). The final design of the vulnerability analyses has not yet been finalized by the project team. The vulnerability analysis simulation framework is 80% complete. The team has selected the COA water utility to be the subject of the vulnerability assessment, and work has begun on initial data collection and developing the utility personnel contacts.
Changes to Aims
Our original proposal included six aims (A-F), and we have decided to focus our energies on four of them, for the reasons outlined here. We have decided not to pursue the following two aims:
Aim C: Expand the previously conducted analyses assessing the association between rates of ED visits for GI illness and estimated residence times of drinking water serving the service area by considering an additional utility for the time period 1993 through 2009.
Aim D: Assess the association between rates of ED visits for GI illness and chlorine residual levels measured in the distribution system.
For Aim C, rather than considering an additional utility, we have decided to do additional analyses and focus in depth on one distribution system. We will focus on the utility chosen for the vulnerability assessment described in Aim E. We originally had considered expanding our analysis to the water utility in Gwinnett County, but there have been very significant infrastructure changes in the distribution system during the time period of interest. The work required to expand the analysis to that utility is beyond the scope of this project and may be of limited value because of the infrastructure changes.
For Aim D, upon further analysis of the data, we have discovered that the timing of chlorine residual measurements in the distribution system is problematic for the epidemiologic analytic goal of this study aim. Chlorine residual levels are collected in monthly grab samples only, whereas actual chlorine levels in the distribution system can fluctuate hourly. The infrequency with which chlorine residual samples were collected would result in a loss of statistical power for observing associations between chlorine residual and health outcomes. In addition, the sites sampled by the utilities are distributed throughout the distribution system, but each site is typically not sampled every month. This is problematic for valid temporal analyses. Although an epidemiological analysis cannot be supported given the infrequency of chlorine residual measurements, we will: 1) assess the relationship between monthly chlorine residual and distribution system modeled vulnerability (Aim E), and 2) compare monthly chlorine residual measurements to continuous chlorine residual monitoring using the AMS unit (Aim F).
Future Activities:
Planned Activity for Years 2 and 3
Year 2 goals:
- Complete analysis for Aim A.
- Develop water residence time estimates for Utilities 1 & 2 through 2009.
- Perform analysis for Aim B.
- Complete distribution system pathogen contamination vulnerability assessment of selected utility (Aim E).
- Initiate continuous monitoring of distribution system water quality at utility for which vulnerability assessment was conducted (Aim F).
- Write manuscript for Aims A and B and submit it for publication.
Year 3 goals:
- Perform analysis for Aim E.
- Complete distribution system monitoring (Aim F).
- Write manuscripts for Aims E and F and submit them for publication.
Journal Articles:
No journal articles submitted with this report: View all 14 publications for this projectSupplemental Keywords:
water, drinking water, exposure, risk, health effects, human health, vulnerability, population, indicators, public policy, epidemiology, engineering, modeling, monitoring, Georgia, GAProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- Final Report
- 2013 Progress Report
- 2012 Progress Report
- 2011 Progress Report
- 2010 Progress Report
- Original Abstract
1 journal articles for this project