What is the maximum fluoride concentration advised for drinking water for children under 9 years of age?

The maximum fluoride concentration advised for drinking water for children under 9 years of age is 1.5 mg/l. This standard is established by health organizations because excessive exposure to fluoride during this critical period of dental development can lead to dental fluorosis, a condition that affects the appearance of the teeth.

Fluoride is beneficial in preventing tooth decay, but the balance is key, especially for children whose teeth are still developing. Thus, health guidelines recommend a maximum concentration to ensure that children receive the protective benefits of fluoride while minimizing the risk of adverse effects.

The other concentrations listed might be related to different contexts of fluoride exposure or guidelines for populations not at risk of developing fluorosis, but they do not align with the recommended maximum for children under 9 years of age specifically aimed at preventing excessive fluoride intake.