Fluoride
Harford County Department of Public Works
Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems. Read More.
Fluoride has been promoted as a chemical that reduces dental cavities. Yet it is now well-established that fluoride primarily exerts its protective effects through topical mechanisms, such as sodium fluoride in toothpaste and mouthwash. In contrast, long-term ingestion of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth. EPA's maximum legal limit is set at 4 parts per million (ppm) to prevent skeletal fluorosis, a condition where bones become brittle and more susceptible to fractures, although these effects may occur at lower doses.
Even fluoride levels of 0.7 ppm, the amount of fluoride in drinking water recommended by the U.S. Public Health Service, can result in too much fluoride for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water. The National Toxicology Program is investigating the potential for low doses of fluoride to alter thyroid function and childhood brain development.
Testing results - average by year
Year | Average result | Samples taken | Detections | Range of results |
---|---|---|---|---|
2013 | N/A | 0 | 0 | N/A |
2014 | 0.509 ppm | 2 | 2 | 0.454 ppm - 0.564 ppm |
2015 | 0.535 ppm | 4 | 3 | ND - 0.780 ppm |
2016 | 0.442 ppm | 2 | 2 | 0.429 ppm - 0.454 ppm |
2017 | 0.589 ppm | 4 | 4 | 0.511 ppm - 0.660 ppm |
2018 | 0.402 ppm | 6 | 4 | ND - 0.950 ppm |
2019 | 0.410 ppm | 7 | 6 | ND - 0.600 ppm |
ppm = parts per million
State and national drinking water standards and health guidelines
EPA Maximum Contaminant
Level (MCL) 4 ppm
ppm = parts per million
All test results
Date | Lab ID | Result |
---|---|---|
2014-04-14 | 140414_03_L50154 | 0.454 ppm |
2014-04-14 | 140414_02_L50154 | 0.564 ppm |
2015-02-13 | 150213_01_205474 | 0.680 ppm |
2015-02-13 | 2054742001 | 0.680 ppm |
2015-04-06 | 2063480001 | 0.780 ppm |
2015-04-06 | 2063479001 | ND |
2016-04-04 | L6167674_1 | 0.454 ppm |
2016-04-04 | L6167673_1 | 0.429 ppm |
2017-04-05 | L6756568_1 | 0.511 ppm |
2017-04-05 | L6756571_1 | 0.523 ppm |
2017-07-11 | 2245208001 | 0.660 ppm |
2017-10-06 | 2267469001_A | 0.660 ppm |
2018-02-12 | 2295319001_A | 0.620 ppm |
2018-05-07 | 8051043_03 | 0.430 ppm |
2018-05-07 | 8051039_03 | 0.950 ppm |
2018-11-01 | E19001514001 | ND |
2018-11-05 | E19001554003 | 0.410 ppm |
2018-11-05 | E19001554004 | ND |
2019-02-05 | 9020935_01 | 0.560 ppm |
2019-02-12 | 9023686_01 | 0.320 ppm |
2019-05-14 | 9050790_01_A | 0.430 ppm |
2019-05-14 | 9050787_01 | 0.470 ppm |
2019-07-31 | E20000446001 | ND |
2019-09-10 | 9080712_01 | 0.600 ppm |
2019-12-03 | 9110887_01 | 0.490 ppm |