What is the fluoride secondary standard?

• A. One point zero milligrams per liter
• B. Four point zero milligrams per liter
• C. Zero point five milligrams per liter
• D. Two point zero milligrams per liter

Answer: (D)

Fluoride secondary standard is a non-enforceable guideline aimed at protecting aesthetics and public acceptance of drinking water, not at setting a health-based health risk limit. It is set at 2.0 mg/L to minimize cosmetic effects like dental fluorosis, taste changes, and staining while still allowing fluoride levels that help prevent tooth decay at lower concentrations. This SMCL sits below the enforceable health-based limit for fluoride, which is 4.0 mg/L, reflecting a balance between dental health benefits and potential cosmetic concerns. So the fluoride secondary standard is 2.0 mg/L.