Formation of non-functional methaemoglobin causes blue-baby syndrome. This is due to

• excess of arsenic concentration in drinking water

• excess of nitrates in drinking water

• deficiency of iron in food

• increased methane content in the atmosphere

B.

excess of nitrates in drinking water

Blue baby syndrome is a blood related condition mostly found in babies due to nitrate poisoning. It particularly limits blood's ability to carry oxygen thereby causing baby to look blue and hence known as metheamoglobanemia. It is a serious illness in infants which is caused when nitrate is converted into nitrite in the infant's body. Nitrite interferes with the oxygen carrying capacity of the child's blood and therby replaces the oxygen on the red blood cells. It is an acute disease and symptoms develop in infants.