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Arsenic Concentrations in Drinking Water and Associations with Bladder Cancer Incidence, Accounting for Population Served
Citation:
Krajewski, A., M. Jimenez, D. Lobdell, Tim Wade, AND J. Jagai. Arsenic Concentrations in Drinking Water and Associations with Bladder Cancer Incidence, Accounting for Population Served. Society for Epidemiologic Research (SER) Meeting, Baltimore, MD, June 19 - 22, 2018.
Impact/Purpose:
Purpose was to examine role of population served in community water systems data in relation to exposure-health outcome studies.
Description:
Drinking water concentrations from community water systems (CWS) have been used to estimate county-level exposure to contaminants, such as arsenic. Many studies neglect to account for how exposure may differ within counties based on population served (PS) by a CWS. Accounting for PS by CWS provides a more direct estimate of individual exposure to a contaminant from drinking water. To explore the influence of PS by CWS, three county-level arsenic exposure measures were constructed: unadjusted for PS; controlled for PS (as a covariate); and accounted for PS (concentration multiplied by proportion of PS by county population). CWS arsenic concentrations, obtained from four northeast states (MA, ME, NH, and RI) for 2000-2009, were aggregated to county-level and linked to county-level bladder cancer incidence for 2010-2014 from National Cancer Institute State Cancer Profiles. Poisson regression models estimated incidence rate ratios (IRR) and 95% CI for associations between bladder cancer and four arsenic exposure categories (50 ppb), adjusting for potential confounders. For unadjusted arsenic concentrations, the IRRs were 1.65 (95% CI: 1.26, 2.16), 1.02 (95% CI: 0.79, 1.33) and 1.81 (95% CI: 1.38, 2.38) for categories 2-4, compared to <10 ppb, the lowest exposure category. For arsenic concentrations controlled by PS, the IRRs were 1.24 (95% CI: 0.93, 1.64), 0.72 (95% CI: 0.54, 0.96) and 1.41 (95% CI: 1.06, 1.86) for categories 2-4, compared to <10 ppb. After accounting for PS, the IRRs were 0.62 (95% CI: 0.49, 0.80), 1.15 (95% CI: 1.02, 1.30) and 1.16 (95% CI: 1.02, 1.32) for categories 2-4, compared to <10 ppb. Using different methods with respect to PS by CWS in measured drinking water arsenic concentrations resulted in positive but varied associations to bladder cancer. Thus, it is important to account for PS when developing drinking water exposure measures. This abstract does not reflect EPA policy.