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As of 2023, 440 districts in India have excessive nitrates in groundwater, up from 359 in 2017, with 56% of districts affected.
19.8% of 15,239 groundwater samples exceeded safe nitrate levels, showing little change since 2017 (21.6% in 2017).
Rajasthan (49%), Karnataka (48%), and Tamil Nadu (37%) had the highest levels of nitrate contamination.
Central and southern India, including Maharashtra, Telangana, and Andhra Pradesh, show increasing nitrate contamination trends.
Nitrate levels rise during the monsoon, with contamination increasing from 30.77% pre-monsoon to 32.66% post-monsoon.
Fluoride and uranium contamination are major issues, especially in Rajasthan, Haryana, and Punjab.
Uranium levels exceeding 100 ppb are particularly concerning in areas with over-exploited groundwater.
The national groundwater extraction rate is 60.4%, with 73% of analyzed blocks in the "safe" zone, a significant improvement from 67.4% in 2022.
Nitrate Contamination
The primary cause is the extensive use of subsidized synthetic nitrogenous fertilizers in farming.
High nitrate levels (above 45 mg/l) pose health risks, particularly to young children, and contribute to environmental toxicity.
Excessive nitrate levels in drinking water react with haemoglobin, forming non-functional methaemoglobin and hindering oxygen transport, leading to methemoglobinemia and blue baby syndrome.
High nitrate levels can also contribute to the formation of carcinogens and accelerate eutrophication.
Blue Baby Syndrome cause a bluish discolouration of the skin in babies
Methemoglobinemia is a condition where an abnormal form of haemoglobin (methemoglobin) is present in the blood, reducing its ability to carry oxygen.
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