Which one of the following is responsible for blue baby syndrome ?

Blue baby syndrome, medically known as infantile methemoglobinemia, is primarily caused by high nitrate contamination in drinking water [c1][t1]. When infants ingest water or formula prepared with nitrate-rich water, bacteria in their digestive system convert nitrates into nitrites [t2][t4]. These nitrites oxidize the iron in hemoglobin from the ferrous (Fe2+) to the ferric (Fe3+) state, forming methemoglobin [t3][t4]. Unlike normal hemoglobin, methemoglobin cannot effectively transport oxygen to body tissues, leading to hypoxia and a characteristic bluish skin discoloration known as cyanosis [t2][t3][t9]. This condition is particularly dangerous for infants under six months of age [t3][t8]. Common sources of nitrate contamination include agricultural runoff from fertilizers, leaching from waste dumps, and poorly constructed wells [c1][t1][t7]. While other substances like fluoride cause skeletal issues and arsenic leads to poisoning, nitrate is the specific agent responsible for this oxygen-deprivation syndrome [c2][c5].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > d) Blue baby syndrome > p. 416
2. [2] https://www.doh.wa.gov/portals/1/Documents/pubs/331-214.pdf
3. [3] https://www.sciencedirect.com/science/article/abs/pii/S0273230096900069
4. [4] https://www.sciencedirect.com/topics/medicine-and-dentistry/blue-baby-syndrome
5. [5] https://pmc.ncbi.nlm.nih.gov/articles/PMC1247562/
6. [6] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 3. Hazards of ground water pollution: > p. 76