Water Fluoridation Concentration — ORE Part 1 MCQ
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Correct answer: A — 0.7–1.0 mg/L
Explanation lettering: E = shown as B · D = shown as C · B = shown as D · C = shown as E
The WHO-recommended optimal fluoride concentration for caries prevention in community water fluoridation lies within the range 0.5–1.5 mg/L, with 1.0 mg/L (1 ppm) representing the UK target concentration supported by evidence of dental health benefit and safety. Option A (0.7–1.0 mg/L) captures this practical optimal range. Option B (0.1 mg/L) is below the effective threshold for caries prevention. Options C (5.0 mg/L), D (10 mg/L), and E (0.01 mg/L) are implausibly high or too low respectively; levels above 1.5 mg/L exceed the WHO maximum and risk dental fluorosis. This item tests understanding of the distinction between WHO's maximum safety limit (1.5 mg/L) and the optimal working concentration for public health benefit.
Reference: UK Department of Health and Social Care & Office for Health Improvement and Disparities (2026). Water fluoridation Health monitoring report for England 2026, and Committee on Toxicity meeting paper on Potential health risks from fluoride at UK exposure levels (March 2026). https://assets.publishing.service.gov.uk/media/69ca73b32c5db1b1db67e966/water-fluoridation-health-monitoring-report-2026.pdf