Which one of the following is a major effect of long term consumption of drinking water containing little (less than 0-5 ppm) or no fluoride ?

Fluoride is a naturally occurring element that plays a critical role in dental health. Long-term consumption of drinking water with little or no fluoride (less than 0.5 ppm) is primarily associated with an increased risk of dental caries, also known as tooth cavities [6]. Fluoride helps prevent cavities by reducing the demineralization of tooth enamel and promoting reminerilization, which repairs early stages of decay [6]. While high concentrations of fluoride (typically above 1.5–2.0 ppm) lead to adverse effects such as dental fluorosis (mottling of teeth), skeletal fluorosis (bone deformation), and joint stiffness [7], a deficiency in fluoride leaves teeth vulnerable to acid-producing bacteria that soften enamel [4]. Therefore, maintaining an optimum level of fluoride (around 0.7–1.0 ppm) is a standard public health measure to prevent tooth decay [7].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > ag.l.s.Fluorine > p. 414
2. [4] NCERT. (2022). Contemporary India II: Textbook in Geography for Class X (Revised ed.). NCERT. > Chapter 5: Print Culture and the Modern World > A bright smile from toothpaste and minerals > p. 105
3. [6] https://www.atsdr.cdc.gov/toxprofiles/tp11-c2.pdf
4. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 3. Hazards of ground water pollution: > p. 76
5. [7] https://pmc.ncbi.nlm.nih.gov/articles/PMC3956646/
6. [3] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Dental caries > p. 86