Distribution of Fluoride in the Phosphorite Mining Area of Hahotoe-Kpogame (Togo)

Gnon Tanouayi; Kissao Gnandi; Kamilou Ouro-Sama; Adoté Agbéko Aduayi-Akue; Housséni Ahoudi; Yawovi Nyametso; Hodabalo Dheoulaba Solitoke

doi:10.5696/2156-9614-6.10.84

Distribution of Fluoride in the Phosphorite Mining Area of Hahotoe-Kpogame (Togo)

J Health Pollut. 2016 Jun 16;6(10):84-94. doi: 10.5696/2156-9614-6.10.84. eCollection 2016 Jun.

Authors

Gnon Tanouayi^{1

2}, Kissao Gnandi^{1

2}, Kamilou Ouro-Sama², Adoté Agbéko Aduayi-Akue², Housséni Ahoudi², Yawovi Nyametso², Hodabalo Dheoulaba Solitoke²

Affiliations

¹ The Geochemical Laboratory (Geology Department); Faculty of Science, University of Lomé, Togo.
² Management, Treatment and Promotion of Wastes Laboratory; Faculty of Science, University of Lomé, Togo.

Abstract

Background: Phosphorites in the mining area of Hahotoé-Kpogamé contain high levels of fluoride that can cause illness among people living close to the mining and processing sites.

Objectives: To assess the distribution of fluoride in the different areas around the phosphorite mining areas in Togo.

Methods: Analyses were performed by molecular absorption spectrometer (HACH DR3800) according to the procedure manual at the geochemical laboratory of the University of Lomé. The sodium 2 - (parasulfophenylazo) - 1,8 - dihydroxy - 3,6 - naphthalenedisulfonate (SPADNS) method was used to determine fluoride contents and the PhosVer^® 3 with acid persulfate digestion method was used to measure phosphorus pentoxide (P₂O₅). GraphPad Prism version 3.0 software was used for the data processing.

Results: The surface water of the mining sites had a fluoride content ranging from 0.38 to 3.52 mg/l (average = 1.33 mg/l; n = 10, n is the number of samples). Groundwater in this area had a fluoride content between 0.15 mg/l and 1.39 mg/l (average = 0.58 mg/l, n = 15). In the groundwater in the villages around the phosphorite processing plant, the fluoride content ranged between 0.15 and 0.63 mg/l (average = 0.41 mg/l; n = 22). The fluoride content in the water of the phosphorite mining area was higher than in Gbodjomé (reference area). Meanwhile, assessment of the effluents discharged into the ocean had a fluoride content ranging from 12 to 20 mg/l. In dusts, the P₂O₅ and fluoride contents were 36.02% and 1.85%, respectively. Vegetables from the local market garden produce showed levels of fluoride up to 2.06%. The average contents of P₂O₅ and fluoride in one of the phosphorite profiles were 32.38% and 3.00%, respectively. A significant correlation was observed between P₂O₅ and fluoride.

Conclusions: The correlation between P₂O₅ and fluoride in phosphorites shows that phosphorite mining is the main source of fluoride pollution in this area.

Keywords: Hahotoé-Kpogamé; Togo; dental fluorosis; fluoride; ground and surface water; phosphorites.