title: Community drinking water quality monitoring data: utility for public health research and practice.
abstract: BACKGROUND
  Environmental Public Health Tracking (EPHT) tracks the occurrence and magnitude of environmental hazards and associated adverse health effects over time. The EPHT program has formally expanded its scope to include finished drinking water quality.
  
  
  OBJECTIVE
  Our objective was to describe the features, strengths, and limitations of using finished drinking water quality data from community water systems (CWSs) for EPHT applications, focusing on atrazine and nitrogen compounds in 8 Midwestern states.
  
  
  METHODS
  Water quality data were acquired after meeting with state partners and reviewed and merged for analysis.
  
  
  RESULTS
  Data and the coding of variables, particularly with respect to censored results (nondetects), were not standardized between states. Monitoring frequency varied between CWSs and between atrazine and nitrates, but this was in line with regulatory requirements. Cumulative distributions of all contaminants were not the same in all states (Peto-Prentice test P < .001). Atrazine results were highly censored in all states (76.0%-99.3%); higher concentrations were associated with increased measurement frequency and surface water as the CWS source water type. Nitrate results showed substantial state-to-state variability in censoring (20.5%-100%) and in associations between concentrations and the CWS source water type.
  
  
  CONCLUSIONS
  Statistical analyses of these data are challenging due to high rates of censoring and uncertainty about the appropriateness of parametric assumptions for time-series data. Although monitoring frequency was consistent with regulations, the magnitude of time gaps coupled with uncertainty about CWS service areas may limit linkage with health outcome data.
authors.affiliation: Divisions of Environmental and Occupational Health Sciences (Dr Jones) and Epidemiology and Biostatistics (Drs Graber, Turyk, and Stayner), School of Public Health, and Department of Civil and Materials Engineering, College of Engineering (Dr Rockne), University of Illinois at Chicago.
authors.forename: Rachael M
authors.initials: RM
authors.lastname: Jones
authors.forename: Judith M
authors.initials: JM
authors.lastname: Graber
authors.forename: Robert
authors.initials: R
authors.lastname: Anderson
authors.forename: Karl
authors.initials: K
authors.lastname: Rockne
authors.forename: Mary
authors.initials: M
authors.lastname: Turyk
authors.forename: Leslie T
authors.initials: LT
authors.lastname: Stayner
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000209:etiology / Q000517:prevention & control; D016573:Agrochemicals / Q000009:adverse effects / Q000032:analysis; D001280:Atrazine / Q000009:adverse effects / Q000032:analysis*; D003627:Data Interpretation, Statistical; D060766:Drinking Water / Q000032:analysis / Q000592:standards*; D006801:Humans; D009566:Nitrates / Q000009:adverse effects / Q000032:analysis*; D015980:Public Health Practice / Q000592:standards*; D014481:United States; D014874:Water Pollutants, Chemical / Q000009:adverse effects / Q000032:analysis; D060753:Water Quality / Q000592:standards*
chemical_list: D016573:Agrochemicals; D060766:Drinking Water; D009566:Nitrates; D014874:Water Pollutants, Chemical; D001280:Atrazine