title: Social disparities in nitrate-contaminated drinking water in California's San Joaquin Valley.
abstract: BACKGROUND
  Research on drinking water in the United States has rarely examined disproportionate exposures to contaminants faced by low-income and minority communities. This study analyzes the relationship between nitrate concentrations in community water systems (CWSs) and the racial/ethnic and socioeconomic characteristics of customers.
  
  
  OBJECTIVE
  We hypothesized that CWSs in California's San Joaquin Valley that serve a higher proportion of minority or residents of lower socioeconomic status have higher nitrate levels and that these disparities are greater among smaller drinking water systems.
  
  
  METHODS
  We used water quality monitoring data sets (1999-2001) to estimate nitrate levels in CWSs, and source location and census block group data to estimate customer demographics. Our linear regression model included 327 CWSs and reported robust standard errors clustered at the CWS level. Our adjusted model controlled for demographics and water system characteristics and stratified by CWS size.
  
  
  RESULTS
  Percent Latino was associated with a 0.04-mg nitrate-ion (NO3)/L increase in a CWS's estimated NO3 concentration [95% confidence interval (CI), -0.08 to 0.16], and rate of home ownership was associated with a 0.16-mg NO3/L decrease (95% CI, -0.32 to 0.002). Among smaller systems, the percentage of Latinos and of homeownership was associated with an estimated increase of 0.44 mg NO3/L (95% CI, 0.03-0.84) and a decrease of 0.15 mg NO3/L (95% CI, -0.64 to 0.33), respectively.
  
  
  CONCLUSIONS
  Our findings suggest that in smaller water systems, CWSs serving larger percentages of Latinos and renters receive drinking water with higher nitrate levels. This suggests an environmental inequity in drinking water quality.
authors.forename: Carolina
authors.initials: C
authors.lastname: Balazs
authors.forename: Rachel
authors.initials: R
authors.lastname: Morello-Frosch
authors.forename: Alan
authors.initials: A
authors.lastname: Hubbard
authors.forename: Isha
authors.initials: I
authors.lastname: Ray
mesh_terms: D002140:California; D060766:Drinking Water / Q000737:chemistry*; D004781:Environmental Exposure / Q000706:statistics & numerical data; D004784:Environmental Monitoring; D006630:Hispanic or Latino; D006801:Humans; D008913:Minority Groups; D009566:Nitrates / Q000032:analysis*; D012923:Social Class; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D014881:Water Supply / Q000706:statistics & numerical data*
chemical_list: D060766:Drinking Water; D009566:Nitrates; D014874:Water Pollutants, Chemical