Public health engineering — health impacts of excessive fluoride in drinking water Which of the following conditions are typically associated with intake of fluoride above permissible limits in drinking water?

Introduction / Context:
Fluoride occurs naturally in many aquifers. While small amounts help prevent dental caries, chronic exposure above guideline values leads to dental and skeletal fluorosis. Recognizing the specific health outcomes tied to fluoride is essential for water quality surveillance and appropriate mitigation (defluoridation, blending, or alternate sources).

Given Data / Assumptions:

• We focus on long-term exposure to high fluoride levels in drinking water.
• Population-level effects include both dental and skeletal manifestations.
• Other listed diseases have different etiologies unrelated to fluoride.

Concept / Approach:
At concentrations above permissible limits, fluoride disrupts mineralization processes: in children, enamel hypomineralization produces dental mottling (white to brown streaks/spots); in adults and with higher exposures, it causes skeletal fluorosis characterized by bone pain, stiffness, and increased brittleness due to altered bone remodeling. The association is well documented in endemic regions and forms the basis for regulatory limits and advisories.

Step-by-Step Solution:
Identify the agent: fluoride in drinking water above guideline values.Map to outcomes: dental fluorosis (mottling) and skeletal fluorosis (bone brittleness/osteosclerosis).Reject unrelated conditions: methemoglobinemia is linked to nitrate; skin cancers have multi-factor causes; Alzheimer’s and lead poisoning are unrelated to fluoride exposure.

Verification / Alternative check:
Epidemiological and clinical literature from high-fluoride belts consistently reports these manifestations; interventions reducing fluoride levels reverse early dental signs and mitigate skeletal progression.

Why Other Options Are Wrong:
Alzheimer’s disease: no conclusive causal link with fluoride.
Methemoglobinemia: associated with high nitrate, not fluoride.
Skin cancer: not a recognized outcome of fluoride in drinking water.
Lead poisoning: a different contaminant entirely.

Common Pitfalls:

• Confusing cosmetic dental mottling (reversible early) with irreversible severe dental fluorosis.
• Overlooking cumulative dose and duration as key determinants of skeletal effects.

Final Answer:
Mottling of teeth and embrittlement of bones