Drinking water standards — health effect of excess fluoride (If fluoride concentration exceeds 1.5 mg/L, what condition is typically caused?)

Introduction / Context:
Fluoride in drinking water has a narrow beneficial-to-adverse window. While low levels can reduce dental caries, concentrations above recommended limits lead to characteristic health issues, most notably dental fluorosis in children.

Given Data / Assumptions:

• Permissible limit considered: about 1.5 mg/L.
• Exposure is chronic via drinking water.
• Population includes children whose teeth are developing.

Concept / Approach:
Fluoride integrates into enamel during tooth formation. Excess interferes with ameloblast activity, producing hypomineralization and mottling of enamel (dental fluorosis). At still higher long-term intakes, skeletal fluorosis can occur, but the earliest, most typical manifestation above 1.5 mg/L is dental fluorosis.

Step-by-Step Solution:
1) Identify the contaminant: fluoride.2) Compare with permissible limit: > 1.5 mg/L.3) Associate the well-known health effect at these levels: dental fluorosis.4) Select option matching this outcome.

Verification / Alternative check:
Public health guidelines link higher-than-permissible fluoride to brown mottling, pitting, and chalky white patches on teeth.

Why Other Options Are Wrong:
Cardiovascular disease, methemoglobinemia (nitrate-related), and hepatitis are not characteristic outcomes of fluoride at this range.

Common Pitfalls:
Confusing fluoride with nitrite/nitrate effects; assuming any dental discoloration is due to poor hygiene rather than fluoride exposure history.

Final Answer:
dental fluorosis