The BIS (Bureau of Indian Standards) standard for drinking water quality specifies the maximum permissible limit of nitrates in drinking water as:

• A 10 mg/L (as NO3-)
• B 45 mg/L (as NO3-) ✓
• C 100 mg/L (as NO3-)
• D 50 mg/L (as NO3-)

Explanation

The BIS standard IS 10500:2012 specifies the maximum permissible limit for nitrates in drinking water as 45 mg/L as NO3- (nitrate ion). The WHO guideline is 50 mg/L, while the EPA standard is 10 mg/L as nitrogen (equivalent to approximately 44.3 mg/L as NO3-). High nitrate exposure causes methemoglobinemia (blue baby syndrome) in infants under 3 months, as intestinal flora reduce nitrate to nitrite which oxidizes hemoglobin. Sources include agricultural runoff and contaminated shallow wells.

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.