Blue-baby syndrome is caused by

• A. Cadmium pollution
• B. Mercury poisoning
• C. Chronic exposure to arsenic
• D. Excess nitrate in drinking water
• E. Excess fluoride in drinking water

Blue-baby syndrome, also known as methemoglobinemia, primarily occurs due to excess nitrate in drinking water. This condition affects the ability of blood to carry oxygen, leading to a bluish tint in the skin, especially in infants.

Causes of Blue-Baby Syndrome

The main culprit behind this syndrome is:

• D. Excess nitrate in drinking water

Why Nitrate is Harmful

Nitrates can convert hemoglobin in the blood to methemoglobin, which cannot effectively transport oxygen. This is particularly dangerous for young children, whose bodies are still developing.

Other Options Explained

While cadmium, mercury, arsenic, and fluoride can cause various health issues, they are not directly linked to blue-baby syndrome:

• A. Cadmium pollution - linked to kidney damage and bone disease.
• B. Mercury poisoning - affects the nervous system.
• C. Chronic exposure to arsenic - associated with cancer and skin lesions.
• E. Excess fluoride in drinking water - primarily causes dental fluorosis.

In summary, the correct answer is D, as excess nitrates in drinking water pose the greatest risk for developing blue-baby syndrome.