The permissible fluoride level in drinking water as per Bureau of Indian Standards (BIS: 10500) is:
- A 1.0 mg/L (desirable limit); 1.5 mg/L (permissible limit in absence of alternate source) ✓
- B 0.5 mg/L (desirable); 1.0 mg/L (permissible)
- C 1.5 mg/L (desirable); 3.0 mg/L (permissible)
- D 2.0 mg/L flat limit with no distinction
Correct answer: A. 1.0 mg/L (desirable limit); 1.5 mg/L (permissible limit in absence of alternate source)
Explanation
BIS 10500 (2012 revision) specifies that the desirable limit for fluoride is 1.0 mg/L (adequate to prevent dental caries without causing fluorosis) and the permissible limit (acceptable only in the absence of an alternative water source) is 1.5 mg/L. The WHO guideline is also 1.5 mg/L. Levels above 1.5 mg/L cause dental fluorosis; levels > 3–4 mg/L over years cause skeletal fluorosis. The concept of a 'two-tier' limit is important — desirable does not equal permissible.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.