The Bureau of Indian Standards (BIS IS 10500:2012) specifies a permissible limit for fluoride in drinking water of 1.0 mg/L (desirable) and 1.5 mg/L (permissible in absence of alternative). Chronic exposure above 1.5 mg/L primarily causes:
- A Dental fluorosis followed by skeletal fluorosis at higher levels ✓
- B Methemoglobinemia in infants
- C Blue baby syndrome
- D Arsenicosis with Mees' lines
Correct answer: A. Dental fluorosis followed by skeletal fluorosis at higher levels
Explanation
Fluoride in drinking water: 0.5–0.8 mg/L is optimal for prevention of dental caries; 1.5–4 mg/L causes dental fluorosis (mottled enamel); >4 mg/L causes skeletal fluorosis (osteosclerosis, periosteal proliferation, crippling fluorosis at >10 mg/L). Methemoglobinemia (blue baby syndrome) is caused by excess nitrates, not fluoride. Arsenicosis with Mees' lines results from arsenic exposure. India has endemic fluorosis in 20+ states, making this a high-yield environmental health topic.
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.