Geochemical behavior of fluoride-rich groundwater in Markapur, Andhra Pradesh, South India.

Excess fluoride in drinking water has been one of the leading problem faced by the arid and semi-arid regions of the world. Significantly in India the people suffer from fluorosis comparing to other toxic elements like Arsenic etc., in drinking water. Approximately, in India the excessive fluoride in groundwater is noticed in 177 districts covering 21 states, affecting 66 million people, including 6 million children and Moreover, the latest estimation gives nearly 200 million people, from among 25 nations the world over, are affected by the deadly disease of fluorosis [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14]. The fluoride of the groundwater varies from 0.4 to 5.8 mg/L with a mean of 1.98 mg/L (Table 1 & 2), which indicates that the concentration of fluoride is not uniform in the study area. In general intake of small quantities of fluoride in the permissible limit of 0.5 to 1 mg/L is known to be beneficial for human health in production and maintenance of proper health. However, in India safe limit of fluoride in potable water is considered to be between 0.6 to 1.2 mg/L, less than 0.6 mg/L can cause dental caries, while higher than 1.2 mg/L leads to fluorosis [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16].