What should be particularly monitored due to their effects on infant health?

Monitoring nitrate levels in drinking water is crucial due to their specific health effects on infants. High concentrations of nitrates can lead to a condition known as methemoglobinemia or "blue baby syndrome," which affects the ability of hemoglobin in the blood to carry oxygen. Infants are particularly vulnerable to this condition because their digestive systems are still developing and can convert nitrates to nitrites more efficiently than those of older children or adults.

While lead, chlorine, and fluoride levels are also important to monitor for various health reasons, they do not specifically target the critical concerns associated with infant health. For example, lead can lead to neurological problems and developmental delays, but the direct correlation with infant health is not as immediate as that of nitrates. Chlorine is often used as a disinfectant, and while high levels can cause health issues, they are generally more concerning for long-term exposure rather than acute effects on infants. Fluoride is added to promote dental health, and its effects are generally favorable when managed properly, though excessive exposure can lead to dental fluorosis rather than the acute health challenges presented by elevated nitrate levels. Therefore, monitoring nitrate levels is particularly vital for the protection of infant health.