Fluoride
City of Lewiston
Fluoride occurs naturally in surface and groundwater and is also added to drinking water by many water systems to prevent cavities and support oral health in people.
In 2015, the Department of Health and Human Services updated its recommendation of an optimal level of 0.7 parts per million, or ppm, added to drinking water based on the health benefits of tooth decay prevention. Studies have shown that fluoride added to community water systems at this level reduces dental cavities, especially in children.
And studies have conclusively shown that fluoride in toothpaste and mouthwash can also provide these benefits.
Read More.
Health Concerns
Although the HHS-recommended level of 0.7 ppm can help promote oral health in children and adults, this level is likely too high for bottle-fed babies. EWG recommends that caregivers mix baby formula with fluoride-free water.
And fluoride in water at higher levels can be detrimental for everyone, especially children.
Long-term ingestion of higher levels of fluoride in water increases dental fluorosis, which includes mottling, pitting and weakening of the teeth in children.
A 2024 authoritative assessment by the National Toxicology Program found that higher levels of fluoride exposure, such as drinking water containing more than 1.5 ppm of fluoride, are associated with lower IQ in children. The conclusion was based on studies in human populations outside of the U.S.
Affecting systems with naturally occurring fluoride, 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 fracture. But these effects may occur at lower levels of exposure, raising concerns that the current limit may not adequately protect public health.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | 0.609 ppm | 2 | 2 | 0.339 ppm - 0.879 ppm |
| 2019 | 0.297 ppm | 5 | 4 | ND - 0.640 ppm |
| 2020 | 0.577 ppm | 5 | 5 | 0.352 ppm - 0.839 ppm |
| 2021 | 0.537 ppm | 5 | 5 | 0.252 ppm - 0.797 ppm |
| 2022 | 0.879 ppm | 2 | 2 | 0.417 ppm - 1.34 ppm |
| 2023 | N/A | 0 | 0 | N/A |
ppm = parts per million
State, National, and Health Guidelines for Drinking Water
EPA Maximum Contaminant
Level (MCL): 4 ppm
ppm = parts per million
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2018-02-21 | I180221045-001 | 0.339 ppm |
| 2018-02-22 | I180223004-001 | 0.879 ppm |
| 2019-01-24 | I190124017-001 | 0.307 ppm |
| 2019-04-23 | I190423067-001 | 0.640 ppm |
| 2019-04-23 | I190423067-002 | 0.240 ppm |
| 2019-05-15 | I190516039-001 | 0.300 ppm |
| 2019-08-14 | I190814075-003 | ND |
| 2020-06-16 | IMAF0484-01 | 0.560 ppm |
| 2020-07-28 | IMAG0811-05 | 0.839 ppm |
| 2020-07-28 | IMAG0811-07 | 0.627 ppm |
| 2020-07-28 | IMAG0811-01 | 0.352 ppm |
| 2020-07-28 | IMAG0811-03 | 0.508 ppm |
| 2021-06-29 | IMBF0852-01 | 0.797 ppm |
| 2021-06-29 | IMBF0852-04 | 0.764 ppm |
| 2021-06-29 | IMBF0852-07 | 0.364 ppm |
| 2021-06-29 | IMBF0852-03 | 0.510 ppm |
| 2021-06-29 | IMBF0852-06 | 0.252 ppm |
| 2022-09-21 | IMCI0682-01 | 1.34 ppm |
| 2022-12-06 | IMCL0247-01 | 0.417 ppm |