Public health in water supply: Excess fluoride (fluorine) in drinking water most commonly leads to which condition?

Introduction / Context:
Fluoride is a trace element with a narrow beneficial range. Low levels can reduce dental caries, but excessive intake leads to fluorosis. Water treatment decisions rely on understanding this dose-response relationship.

Given Data / Assumptions:

• Drinking water contains fluoride above recommended limits.
• Exposure is chronic over years.
• Population-level health effects are of concern.

Concept / Approach:
Chronic excess fluoride causes dental fluorosis (mottling, enamel hypomineralization) and, at higher exposures, skeletal fluorosis (joint pain, stiffness, bone changes). The mechanism involves altered mineralization processes in developing teeth and bone.

Step-by-Step Solution:
1) Identify contaminant: fluoride (F−) at elevated concentration.2) Map to health effect: excess → fluorosis (dental first; skeletal with prolonged high doses).3) Distinguish from cavities: low fluoride reduces caries; excess does not cause cavities.4) Conclude: the principal condition is fluorosis.

Verification / Alternative check:
Epidemiological studies in endemic regions consistently link high-fluoride groundwater with dental and skeletal fluorosis; defluoridation (e.g., activated alumina, Nalgonda process) reduces incidence.

Why Other Options Are Wrong:
Dental cavities/tooth decay: Associated with insufficient fluoride, not excess.Respiratory disease: Not a primary outcome of fluoride in water.

Common Pitfalls:
Assuming “more fluoride is always better.”Ignoring children's heightened susceptibility during enamel formation.

Final Answer:
Fluorosis