Using an environmental public health tracking biomonitoring study to validate safe water restoration efforts in Florida.

Context: Inorganic arsenic is a carcinogen when consumed over many years and is the type of arsenic that is associated with well water. Private wells in many central Florida counties have been found to contain levels of arsenic above 10 μg/L, which is the maximum contaminant level (MCL) established by the US Environmental Protection Agency.

Objective: The purpose of this study was to test whether individuals living in homes with arsenic levels above the MCL who use bottled water or have a point of use (POU) filter on their main source of water in the house (eg, kitchen sink) are ingesting unsafe levels of arsenic through other unfiltered water sources in the home.

Design: Case-control study of residents with private wells above (case) and below (control) the MCL for arsenic in drinking water (10 μg/L) conducted between April and July 2013.

Setting And Participants: Residents with private wells living in Hernando County, Florida, where nearly 400 unique wells of 1200 tested have been found to have elevated arsenic levels (targeted sampling).

Intervention: Participants with elevated water arsenic levels were referred to the Florida Safe Water Restoration Program for assistance in obtaining bottled water vouchers and/or POU filters.

Main Outcome Measures: Creatinine-corrected total urinary arsenic levels and information on water use and consumption behaviors, dietary intake, and other possible exposure sources.

Results: Total urinary arsenic levels were similar for cases using POU filters or bottled water when compared with controls (geometric means of 7.17 and 7.19 μg/L, respectively).

Conclusions: The current practice used by the Florida Safe Water Restoration Program of supplying POU filters or bottled water to households with arsenic levels in private wells between 10 and 50 μg/L appears to be sufficient to protect residents from arsenic exposure through tap water.