Fluoride occurrence in United States groundwater
May 11, 2020
Data from 38,105 wells were used to characterize fluoride (F) occurrence in untreated United States (U.S.) groundwater. For domestic wells (n = 11,032), water from which is generally not purposely fluoridated or monitored for quality, 10.9% of the samples have F concentrations >0.7 mg/L (U.S. Public Health Service recommended optimal F concentration in drinking water for preventing tooth decay) (87% are <0.7 mg/L); 2.6% have F > 2 mg/L (EPA Secondary Maximum Contaminant Level, SMCL); and 0.6% have F > 4 mg/L (EPA MCL). The data indicate the biggest concern with F in domestic wells at the national scale could be one of under consumption of F with respect to the oral-health benchmark (0.7 mg/L). Elevated F concentrations relative to the SMCL and MCL are regionally important, particularly in the western U.S. Statistical comparisons of potentially important controlling factors in four F-concentration categories (<0.1–0.7 mg/L; >0.7–2 mg/L; >2–4 mg/L; >4 mg/L) at the national scale indicate the highest F-concentration category is associated with groundwater that has significantly greater pH values, TDS and alkalinity concentrations, and well depths, and lower Ca/Na ratios and mean annual precipitation, than the lowest F-concentration category. The relative importance of the controlling factors appears to be regionally variable. Three case studies illustrate the spatial variability in controlling factors using groundwater-age (groundwater residence time), water-isotope (evaporative concentration), and water-temperature (geothermal processes) data. Populations potentially served by domestic wells with F concentrations <0.7, >0.7, >2, and >4 mg/L are estimated to be ~28,200,000, ~3,110,000; ~522,000; and ~172,000 people, respectively, in 40 principal aquifers with at least 25 F analyses per aquifer.
Citation Information
Publication Year | 2020 |
---|---|
Title | Fluoride occurrence in United States groundwater |
DOI | 10.1016/j.scitotenv.2020.139217 |
Authors | Peter B. McMahon, Craig J. Brown, Tyler D. Johnson, Kenneth Belitz, Bruce D. Lindsey |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Science of the Total Environment |
Index ID | 70210175 |
Record Source | USGS Publications Warehouse |
USGS Organization | California Water Science Center; Colorado Water Science Center; National Water Quality Assessment Program; New England Water Science Center; Pennsylvania Water Science Center |
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Data for Fluoride Occurrence in United States Groundwater
Data from 38,105 wells were used to characterize fluoride occurrence in untreated United States groundwater. The data were retrieved from the U.S. Geological Survey (USGS) National Water Information System (NWIS). Groundwater samples were collected from 1988 to 2017 in the conterminous United States. Data for groundwater included in this dataset are pH, water temperature, and...
Peter B McMahon (Former Employee)
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Ken Belitz
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Data for Fluoride Occurrence in United States Groundwater
Data from 38,105 wells were used to characterize fluoride occurrence in untreated United States groundwater. The data were retrieved from the U.S. Geological Survey (USGS) National Water Information System (NWIS). Groundwater samples were collected from 1988 to 2017 in the conterminous United States. Data for groundwater included in this dataset are pH, water temperature, and...
Peter B McMahon (Former Employee)
Research Hydrologist
Research Hydrologist
Craig J Brown, Ph.D. (Former Employee)
Research Hydrologist
Research Hydrologist
Tyler Johnson (Former Employee)
Research Geographer
Research Geographer
Ken Belitz
Research Hydrologist Emeritus
Research Hydrologist Emeritus
Email
Phone