The maximum permissible limit for fluoride in drinking water is 1.5 mg/liter. This limit is set by the World Health Organization (WHO) and is based on the latest scientific evidence. Fluoride is a naturally occurring mineral that is found in water, soil, and rocks. It is also added to some drinking water supplies to help prevent tooth decay. However, too much fluoride can cause health problems, such as dental fluorosis, which is a condition that causes white spots on the teeth. The WHO recommends that the fluoride concentration in drinking water should not exceed 1.5 mg/liter to protect public health.
Option A: 0.1 mg/liter is too low. This level of fluoride would not be effective in preventing tooth decay.
Option B: 1.5 mg/liter is the correct answer. This is the maximum permissible limit for fluoride in drinking water, as set by the WHO.
Option C: 5 mg/liter is too high. This level of fluoride can cause health problems, such as dental fluorosis.
Option D: 10 mg/liter is much too high. This level of fluoride can cause serious health problems, such as skeletal fluorosis, which is a condition that causes pain and stiffness in the bones.