**Abstract**

This chapter was aimed to identify the relationship between fluoride (F) enrichment and prevalence of endemic fluorosis in a rural area of Nuzendla mandal in Guntur District, Andhra Pradesh, India. The concentration of F varies from 0.5 to 12.4 mg/L in pre-monsoon groundwater and 0.14 to 16.0 mg/L in post-monsoon groundwater in the collected and analyzed fifty water samples. Dental survey conducted in the study area based on Dean Classification Index indicated different degrees of dental fluorosis due to the varying concentrations of F in drinking water. The significant positive correlation is identified between the F content of groundwater and urine fluorosisaffected children. The F level in urine suggests that a high level of endemic fluorosis is prevalent in the Nuzendla mandal due to the consequence of a higher concentration of F in underground aquifers. This study concludes that the high concentration of F in groundwater leads to increased dental deformities among the surveyed people and also urinary F is a good indicator of community exposure F.

**Keywords:** fluoride, Nuzendla mandal, dean classification index, fluorosis, community fluorosis Index

### **1. Introduction**

Fluoride (F) occurs in rocks, soil, air, water, plants, and animals as well as in human body. Fluoride content in subsurface water is controlled by temperature, pH and solubility of F-bearing minerals. The subsurface water, most of which originates from rainfall or surface water bodies, gains minerals during its transport and residency period of earth crust [1, 2]. Continuous intake of F contaminated groundwater (>1.5 mg/L) without proper treatment cause chronic endemic fluorosis. There is a close relationship between environmental F and general health. Fluoride deficiency increases incidences of dental caries among the population, while the excess F intake causes dental, skeletal fluorosis, and other forms of non-skeletal tissue fluorosis. Hydrofluorosis is a major toxicological and public health problem in water-stressed regions.

Fluorosis continues to be an endemic problem around the world. Moderate levels of F ingestion reduce incidences of dental caries and also promote healthy development of bones and teeth [3, 4]. Hydroxylapatite is main mineral phase of the human teeth enamel. Dental fluorosis, which is characterized by mottling of tooth surface, is the most adverse effect of overexposure to dietary F. Fluoride accumulates in dentin, which is the mineralized tissue underlying the enamel, and its chronic overexposure

could cause dentin to crack more easily [4]. Children within the age group of 0–12 years are most prone to fluorosis as their body tissues are in formative stage.

Fluorosis, which was initially considered to be a problem of teeth only, has now turned to be a serious health hazard affecting many other body systems manifesting through joint pains, muscular pain; skeletal deformations, and malformations characterized by increased in bone mass and density, pain and stiffness in backbone, hip region, and other joints. This is because continuous intake of high F causes ligaments of spine become calcified and ossified [5]. Studies indicate that F intake could increase probability of cancer in the kidney and bladder based on tendency for hydrogen fluoride (HF) to form under the acidic conditions such as urine [6].

Fluoride occurs in natural waters mainly in the form of F, whose concentrations may range up to 2800 mg/L [7]. Fluoride levels are high in groundwater where the source minerals such as amphiboles, micas, fluorapatite, topaz, cryolite, certain clays, and villiaumite [8]. Enrichment of F in Geological substrate is from the fluorite mineral phase in the rocks along with the weathering of rocks.

Hydrochemical techniques are normally employed in the water quality management. In these techniques, the data regarding the origin and behavior of major cations (Ca2+, Mg2+, Na+ , K+ ) and anions CO3 2−, HCO3 − , Cl− , SO4 2−) in the groundwater permits the elucidation of the hydrogeochemical compositions of the water [9]. This generally varies depending upon the solubility of the chemical components from the dissolution of the mineral component of the rocks that host the aquifer.

The current work was aimed to investigate the relationship between the consumption of water from natural high F terrain and the prevalence of dental fluorosis in the study area.

### **2. The study area**

#### **2.1 Location and climate of the study area**

Nuzendla mandal is the present study area, which is located in Narasaraopet Revenue Division of Guntur District, Andhra Pradesh, India (**Figure 1**). It lies in

### *Fluoride Geochemistry and Health Hazards: A Case Study DOI: http://dx.doi.org/10.5772/intechopen.105156*

between the latitudes 79°33′28″–79°52′51″ E, and longitudes 15°49′26″ and 16°01′42″ N and extends to an area of about 350 km2 and is distributed in 20 rural villages. The area experiences a semi-arid climate, with minimum and maximum temperatures of 16.8°C and 48.5°C, respectively. Rentachintala of Guntur district (nearest IMD station) records the highest temperatures (48.5°C) during summer (March to May). The daily sunshine hours range from 3.5 to 10.5, with a mean of 7.5. The relative humidity is from 30% to 80% with a mean of 52%. The mean wind velocity ranges from 4.7 to 16.3 km/h, with an average of 10.5 km/h. The wind velocity is higher during the southwest monsoon compared to the rest of the period. The average annual rainfall for a period of 12 years (1991–2013) is 718.38 mm. The semi-arid climate of the study area with average annual rainfall initiates the evaporation process which plays a crucial role in the release of F fluoride from underlying rocks into the groundwater.
