Adjusted Fluoride Concentrations and Control Ranges in 34 States: 2006–2010 and 2015

To inform selection of a control range around the Public Health Service’s recommended 0.7 mg/L drinking water fluoride concentration to prevent tooth decay, the Centers for Disease Control and Prevention’s Water Fluoridation Reporting System data for 2006–2010 and 2015 were analyzed. Monthly average concentration data from 4,251 fluoride-adjusted community water systems for 191,266 of 255,060 system-months (2006–2010) were compared with control ranges 0.6 mg/L to 0.2 mg/L wide. Percentages of system-months within control ranges ≥0.4 mg/L wide (e.g., ±0.2 mg/L) were >83% versus 68% for 0.2 mg/L wide (±0.1 mg/L). In 2015, 70% of adjusted systems maintained averages within ±0.1 mg/L of their system’s annual average for nine of 12 months, 67% used the 0.7 mg/L target and 45% used it with a ±0.1 mg/L control range. Adoption of the 0.7 mg/L target was underway but not completed in 2015. Control ranges narrower than ±0.2 mg/L may be feasible for monthly average fluoride concentration.