| Fluorides are found in the waste discharges from | | | | waste streams, the other main application of fluoride |
| process streams in a number of industries. Significant | | | | removal is the treatment of municipal water supplies |
| amounts of fluoride come from the following: glass | | | | to reduce the fluoride content to 1 ppm or less. |
| manufacturers, electroplating operations, steel and | | | | Fluoride added to city water supplies is a particularly |
| aluminum, pesticides and fertilizer, groundwater and | | | | American dilemma. Most of the modern industrial |
| the semiconductor industry. The original fluoride | | | | world has already tried and rejected fluoridation. |
| effluent levels can vary over a large range, and | | | | Fluoridation of drinking water was originally proposed |
| restrictions on final effluent level depend on place of | | | | as a solution to the toxic waste dilemma of the |
| disposal. When there is any risk of fluoride seeping | | | | aluminum manufacturing industry. Rationale for adding |
| back to water supplies, a limitation of about one ppm | | | | it to tap water has been a claimed but never really |
| fluoride is normal. Apart from treatment of industrial | | | | proven protection against dental caries. |