Fluoride Levels in Surface and Groundwater in Africa: A Review

Abstract

Abstract:Fluoride has been reported to be among natural pollutant of water in Africa. High fluoride levels beyond the recommended World Health Organization limit of 1.5 mg/l has been observed in various Africa countries. However, the information is scattered in different publication medium. Therefore, objective of this work was to put together the information on fluoride levels in surface and groundwater in Africa, and describe the status and distribution of fluoride in water among African countries. This study assembled the secondary data of fluoride concentrations in surface and groundwater from the various literatures in African countries. Such countries represent southern, northern, eastern and western Africa. Descriptive statistics was used and results showed that elevated fluoride concentration occurred in countries such as Tanzania, Kenya, Algeria, Nigeria, Ghana, Malawi, Sudan, Uganda, the Republic of South Africa and Ethiopia. The highest fluoride concentration reported was 2,800 mg/l in Lake Nakuru in Kenya. The high fluoride concentrations in water can be linked to volcanic activities, presence of thermal waters especially those with high pH, gases emitted from earth's crust, granitic and gneissic rocks. The high fluoride in water is severe in countries located in East African Rift Valley like Kenya, Tanzania and Ethiopia. However, all the incidences of highest fluoride levels in water in the Rift Valley countries were found in surface water bodies. This is contrary, as it is expected groundwater to be more concentrated as compared to surface water due to more water rock interaction than in surface water bodies. There was no single study among many studies has reported the long term trend of concentration of fluoride in water with time. Thus, the effort to establish long term trend of fluoride concentration in water should be taken in consideration. This helps to predict future concentration of fluoride and possibility to minimize future risks. Also, fluorosis has also been reported to be endemic in fluoritic areas of Africa though, little is known on other fluoride negative effects. Therefore, more efforts should concentrate on finding appropriate defluoridation techniques to be applied while considering the cost of operation, efficiency, practicability, easy application and environmental friendly.

Drinking water quality from rural handpump-boreholes in Africa

“…High F groundwater's are well documented in both countries and have been linked to hydrothermal sources (Bath 1980, Reimann et al 2003, Rivett et al 2019. They are also found in high concentrations in other parts of the East African Rift system (Malago et al 2017). Arsenic was not found above the WHO limit of 10 µg l −1 in any HPB in this study, even though As has been reported to be an issue in some other parts of Africa (e.g.…”

Dental fluorosis and oral health in the African Esophageal Cancer Corridor: Findings from the Kenya ESCCAPE case–control study and a pan‐African perspective

“…Critical exposure ages for development of dental fluorosis are from 1 to 7 years of age during permanent dentition development when excessive fluoride exposure disrupts enamel mineralization, with dental fluorosis externally evident, visually, upon eruption of these permanent teeth. We also asked about water source, as ESCC risk has been linked to consumption of non‐piped water, and in Kenya surface waters have some of the highest fluoride levels worldwide …”

“…We also asked about water source, as ESCC risk has been linked to consumption of non-piped water, 22,23 and in Kenya surface waters have some of the highest fluoride levels worldwide. 24 For the present investigation, socioeconomic factors (job, education and amenities), age, ethnicity, alcohol (by type), tobacco (smoking and smokeless), hot beverages, household air pollution, and family history of ESCC represent potential confounders or effect modifiers. Place of birth and of current residence were obtained, and, with the aid of databases of all Kenyan places (www.geonames.org) and their corresponding GPS coordinates, current residence was geocoded to investigate the potential of spatial clustering of dental fluorosis and of selection bias.…”

Water quality and hydrogeochemical characteristics of groundwater around Mt. Meru, Northern Tanzania

“…In urban areas, contamination is mainly attributed to industrial activities and onsite sanitation (Mjemah et al 2011;Napacho and Manyele 2010;Muzuka 2015, 2016a, b) where as in sub-urban to rural areas it is mainly caused by agriculture activities (Bowell et al 1996;Nkotagu 1996a, b;Bowell et al 1997;Mohammed 2002;Mjemah et al 2011;Napacho and Manyele 2010;Muzuka 2015, 2016a, b). Fluoride is one among the natural contaminants in groundwater systems which are common in volcanic regions of Tanzania (Nanyaro et al 1983;Ghiglieri et al 2010;Malago et al 2017). According to the fluoride groundwater survey in Tanzania, it was found that 30% of waters used for drinking exceed the recommended standard by WHO, 1.5 mg/L (Thole 2013).…”

“…According to the fluoride groundwater survey in Tanzania, it was found that 30% of waters used for drinking exceed the recommended standard by WHO, 1.5 mg/L (Thole 2013). The most affected zones are the areas along the rift system, the central to Lake zone parts (Malago et al 2017). For instance, along the rift system, Nanyaro et al (1983) reported high concentration of 690 mg/L from Lake Momella (Fig.…”