What fluoride concentration can lead to mottling of the enamel on teeth?

The concentration of fluoride that can lead to mottling of the enamel on teeth is recognized to be above 2 mg/l. This condition, known as dental fluorosis, occurs when children are exposed to excessive fluoride during the time their teeth are developing, typically up to the age of 8.

Mottling appears as white spots or streaks on the enamel and can range in severity based on the amount and duration of fluoride exposure. At concentrations above 2 mg/l, the risk of developing dental fluorosis significantly increases, which is why this threshold is key in understanding safe levels of fluoride in drinking water.

In contrast, concentrations below 0.5 mg/l are generally considered to be too low to cause any noticeable effects on dental health, and levels between 0.7 mg/l and 1.0 mg/l are often seen as optimal for cavity prevention without causing fluorosis. Although a specific concentration of 3 mg/l is mentioned, just stating 'exactly 3 mg/l' lacks the context of the general range associated with an increased risk—making the broader category of above 2 mg/l more comprehensive.