title: Environmental justice implications of arsenic contamination in California's San Joaquin Valley: a cross-sectional, cluster-design examining exposure and compliance in community drinking water systems.
abstract: BACKGROUND
  Few studies of environmental justice examine inequities in drinking water contamination. Those studies that have done so usually analyze either disparities in exposure/harm or inequitable implementation of environmental policies. The US EPA's 2001 Revised Arsenic Rule, which tightened the drinking water standard for arsenic from 50 μg/L to 10 μg/L, offers an opportunity to analyze both aspects of environmental justice.
  
  
  METHODS
  We hypothesized that Community Water Systems (CWSs) serving a higher proportion of minority residents or residents of lower socioeconomic status (SES) have higher drinking water arsenic levels and higher odds of non-compliance with the revised standard. Using water quality sampling data for arsenic and maximum contaminant level (MCL) violation data for 464 CWSs actively operating from 2005-2007 in California's San Joaquin Valley we ran bivariate tests and linear regression models.
  
  
  RESULTS
  Higher home ownership rate was associated with lower arsenic levels (ß-coefficient= -0.27 μg As/L, 95% (CI), -0.5, -0.05). This relationship was stronger in smaller systems (ß-coefficient = -0.43, CI, -0.84, -0.03). CWSs with higher rates of homeownership had lower odds of receiving an MCL violation (OR, 0.33; 95% CI, 0.16, 0.67); those serving higher percentages of minorities had higher odds (OR, 2.6; 95% CI, 1.2, 5.4) of an MCL violation.
  
  
  CONCLUSIONS
  We found that higher arsenic levels and higher odds of receiving an MCL violation were most common in CWSs serving predominantly socio-economically disadvantaged communities. Our findings suggest that communities with greater proportions of low SES residents not only face disproportionate arsenic exposures, but unequal MCL compliance challenges.
authors.affiliation: Energy and Resources Group, University of California, Berkeley, CA 94720, USA. carolinabalazs@berkeley.edu
authors.forename: Carolina L
authors.initials: CL
authors.lastname: Balazs
authors.forename: Rachel
authors.initials: R
authors.lastname: Morello-Frosch
authors.forename: Alan E
authors.initials: AE
authors.lastname: Hubbard
authors.forename: Isha
authors.initials: I
authors.lastname: Ray
mesh_terms: D001151:Arsenic / Q000032:analysis* / Q000592:standards; D002140:California; D004784:Environmental Monitoring; D006801:Humans; D008452:Maximum Allowable Concentration; D012923:Social Class; D012935:Social Justice; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000592:standards; D014881:Water Supply / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic