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Public Health · single question

According to the U.S. Public Health Service, the optimal concentration of fluoride in community drinking water is:

  1. 0.7 ppm
  2. 7 ppm
  3. 1.5 ppm
  4. 4 ppm
Show answer and explanation

Correct answer: A. 0.7 ppm

  • A. Correct. The current (2015) USPHS recommendation is 0.7 mg/L (0.7 ppm) for community water fluoridation, balancing caries prevention with the risk of fluorosis.
  • B. 7 ppm is far too high and toxic — not a fluoridation target.
  • C. 1.5 ppm exceeds the recommended optimal level.
  • D. 4 ppm is the EPA maximum contaminant level (an upper safety limit), not the optimal level.

Note: The source listed '7 ppm' — this is a typo; the correct optimal community water fluoridation level is 0.7 ppm.

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