Yes, fluoride in drinking water is generally safe and has been shown to be effective in preventing tooth decay. The optimal level of fluoride in drinking water is 0.7 milligrams per liter (mg/L). This level has been determined to provide the maximum benefit in preventing tooth decay while also minimizing the risk of potential side effects, such as dental fluorosis.

Dental fluorosis is a condition that can occur when a person consumes too much fluoride, either through drinking water or other sources such as toothpaste or mouthwash. Fluorosis can cause white spots or streaks on the teeth, which are usually mild and do not affect the overall health of the teeth. In severe cases, fluorosis can cause more noticeable changes in the appearance of the teeth and may also affect the underlying tooth structure.

The risk of dental fluorosis is related to the amount of fluoride consumed, the duration of exposure, and individual factors such as age and genetics. Children under the age of 8 years are at the highest risk of dental fluorosis, as their teeth are still developing.

However, it is important to note that the benefits of fluoride in preventing tooth decay outweigh the risks of dental fluorosis, especially when the fluoride levels are maintained at the optimal level of 0.7 mg/L. Regular dental check-ups can help to identify and monitor any signs of dental fluorosis and ensure that fluoride exposure is within safe limits.