Fluoride in the drinking water of Pakistan and the possible risk of crippling fluorosis

To explore the possibility of fluoride toxicity, seven hundred and forty seven (747) water samples were collected from surface and ground water sources of sixteen major cities of Pakistan, adopting a uniform sampling design with distribution of samples as: Lahore (79), Kasur (46), Faisalabad (30), Khushab (50), Chakwal (51), Mianwali (30), Jhelum (53), Bahawalpur (60), Karachi (60), Mirpur Khas (55), Peshawar (38), Risalpur (35), Quetta (81), Ziarat (21), Loralai (21), Mastung (37). The comparison of analytical findings with WHO Guidelines of Drinking Water for Fluoride (i.e. 1.5 ppm) has concluded that 16% of the monitored water sources have fluoride concentration beyond the permissible, safe limit of 1.5 mg l 1, falling in the concentration range of 1.6–25 mg l 1. The highest fluoride contamination (22%) has been detected in the Balochistan province followed by 19% in Punjab province. Comparatively higher fluoride levels of >20% in groundwater sources such as hand pumps has supported the possibility of increased ground water contamination, as excessive fluoride concentrations are expected to come from calcium-poor aquifers and from areas where fluoride-bearing minerals are common or where cation exchange of sodium for calcium occurs. Field observations have also indicated the prevalence of fluoride-associated health implications in the study areas with excessive fluoride in water sources. The findings in this study have provided a bidirectional vision for epidemiological investigations as well as for mitigating the issues in the affected vicinities of fluoride-rich areas.