A novel use for data collected under the Clean Water Act for public health analysis

The Clean Water Act was established to “restore and maintain the chemical, physical, and biological integrity of the Nation's waters”. Under this act, the U.S. Environmental Protection Agency (EPA) collects information from states on intended use and impairment of each stream. We hypothesized that counties with waters impaired for drinking and recreational uses have higher rates of gastrointestinal infections (GI). We obtained impairment data and merged it with stream hydrology information from the National Hydrography Dataset Plus and EPA's Reach Attribute Database to estimate the percent of impaired stream length intended for drinking and recreational water per county in the U.S. Limited data are available for drinking and recreational water impairment with only 13 and 27 states providing data, respectively. GI related hospitalization records (ICD-9CM 558.9, 787) were abstracted from the Center for Medicare and Medicaid Services (1991-2004), the only comprehensive national hospitalization dataset. Data were aggregated by county of residence; annual hospitalization rates in the elderly (65+years) per county were calculated. A linear random effects model was used to assess county-level associations between percent impaired waters and hospitalization rates, adjusted for percent of population on public water supply and population density. Rates of GI were not associated with drinking water impairment (B:-0.064; 95% CI: -0.292, 0.164; adjusted - B:-0.014; 95% CI: -0.224, 0.196) and negatively associated with recreational water impairment (B: -0.076; 95% CI: -0.127, -0.026; adjusted - B: -0.092; 95% CI: -0.144, -0.039). GI case counts were low, which may partially account for the lack of association with drinking water impairment. Impairment data from omitted states would confirm or refute these results. Though limited, this analysis demonstrates the feasibility of utilizing data collected for policy in public health analysis. (This abstract does not necessarily reflect EPA policy.)