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Groundwater in parts of three Uttar Pradesh districts - Kanpur Nagar, Kanpur Dehat and Fatehpur - has been found contaminated with hexavalent chromium, with residents reporting fluorescent yellow-green water from handpumps.
State government data identified contamination across about a dozen locations, and a 2025 government report found that 73 to 96 per cent of residents tested had chromium (VI) levels in blood above permissible limits.
The contamination is traced to decades of untreated industrial waste, principally from Kanpur's leather tanning and chromium chemical units and unlined dumps of chromite ore processing residue.
Chromium occurs in two relevant forms: trivalent chromium, which is essentially harmless to humans, and hexavalent chromium, which is toxic and carcinogenic.
India's drinking water standard permits total chromium up to 0.05 mg per litre; chromite is the main ore of chromium and the Sukinda valley in Odisha holds the overwhelming share of India's reserves.
Chromium is a naturally occurring element found in rocks, soil, plants, animals and volcanic dust, and as a metal it is a hard grey solid that resists tarnishing because it forms a thin protective oxide layer on contact with air - the property that makes it valuable in stainless steel, plating and corrosion-resistant alloys. In water and living systems, however, what matters is its oxidation state. Trivalent chromium, Cr(III), is poorly absorbed and is essentially harmless in the quantities found in food and water. Hexavalent chromium, Cr(VI), is far more soluble and mobile in groundwater, crosses cell membranes readily and is reduced inside the cell in ways that damage DNA. It is classified as carcinogenic to humans, and long exposure through drinking water is associated with gastrointestinal damage, liver and kidney injury and skin lesions. Cr(VI) is generated industrially - in chromate and dichromate manufacture, chrome plating and the chrome tanning of leather - so it is a pollution problem rather than a natural one.
Simple Analogy: Chromium in water is like the same person in two roles: as Cr(III) it passes by harmlessly, as Cr(VI) it walks straight into the cell.
Primary law on water pollution; empowers the Central and State Pollution Control Boards to regulate and prosecute polluting discharges
Umbrella legislation under which effluent standards and hazardous waste rules are notified
Govern the storage, treatment and disposal of hazardous industrial waste such as chromium-bearing sludge and residue
Sets the acceptable limit for total chromium in drinking water at 0.05 mg per litre, with no relaxation permitted
India's chromite mining centre, holding the overwhelming share of national reserves, and itself a long-standing case study in chromium contamination of surface and groundwater
Chromium joins arsenic, fluoride, nitrate and iron as the recurring contaminants mapped by the Central Ground Water Board; unlike the others, chromium is almost entirely industrial in origin
The principle applied by Indian courts and the National Green Tribunal to make polluting industries bear the cost of remediation and compensation
The piped drinking water programme, whose relevance in such belts is that piped supply from a safe source is often the only quick alternative to contaminated handpumps
GS Paper 3 > Environment > Pollution and its management
General Awareness > Environment and Chemistry
General Awareness > General Science
Biological Oxygen Demand (BOD) is a standard criterion for
Answer: Pollution assay in aquatic ecosystems
Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds? 1. Decreased salinity in the river 2. Pollution of groundwater 3. Lowering of the water-table Select the correct answer using the code given below:
Answer: 2 and 3 only
The soluble, toxic and carcinogenic oxidation state of chromium, generated by chromate manufacture, chrome plating and chrome tanning
Chromite ore processing residue - the solid waste left after extracting chromate from roasted chromite ore, which leaches Cr(VI) when dumped unlined
The principal ore of chromium, FeCr2O4