Analysis of Fluoride in Kales (Brassicca oleracea) and Tomatoes (Lycopersicum esculentum) from Nakuru County, Kenya

M. Maina, E. Wambu, J. K. Lusweti


As vegetables normally form an integral portion of human diet, occurrence of high fluoride in their edible portions can cause significant human exposure to these fluoride residues. The present study was carried out to analyze of fluoride in kales (Brassicca oleracea) and tomatoes (Lycopersicum esculentum) from Nakuru County, Kenya and compared these levels with the World Health Organization/Food and Agriculture Organization standards. kales and tomatoes were collected from Nakuru County and analyzed using fluoride ion selective electrode. The fluoride concentration in tomatoes from 7 regions was found to vary from 11.66 to 16.70 mg/kg, while in kales it ranged from 5.63 to 17.33 mg/kg. All were above recommended daily allowances (RDA) level of 4 mg/day which poses health hazard to consumers. High F levels were recorded in tomatoes from all the 7 sub-counties of Nakuru County studied. Gilgil had the highest F levels of 16.70 ± 0.46 mg/kg and Nakuru East recorded low levels of 11.66± 0.50mg/kg in tomatoes from all the 7 sub-counties of Nakuru County. Naivasha had the highest levels of fluoride of 17.33 ± 0.55mg/kg and Molo recorded lower levels of 5.63 ± 0.38mg/kg in kales from all the 7 sub-counties of Nakuru County. ANOVA results indicated significant difference in fluoride levels in Njoro Naivasha, Molo-Gilgil and Molo-Naivasha in both tomatoes and kales. It’s apparent from the study that tomatoes and kales were contaminated with high levels of fluoride posing high risks to the health of the consumers.


Fluoride, Kales, Tomatoes, Fluorosis

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Adriano, D. C. and Doner, H. E. (1982). Bromine, Chlorine and Fluorine. In Methods of Soil Analysis.American Society of Agronomy. Madison, WI; pp. 449–83.

Al-Hwaiti, M. and Al-Khashman, O. (2015). Health risk assessment of heavy metals contamination in tomato and green pepper plants grown in soils amended with phosphogypsum waste materials. Environmental geochemistry and health,37 (2), 287–304.

Álvarez-Ayuso, E., Giménez, A. and Ballesteros, J. C. (2011). Fluoride accumulation by plants grown in acid soils amended with flue gas desulphurisation gypsum. Journal of hazardous materials, 192 (3), 1659-1666.

Bhargava, D. and Bhardwaj, N. (2009). Study of Fluoride Contribution Through Water and Food to Human Population in Fluorosis Endemic Villages of North- Eastern Rajasthan African Journal of Basic & Applied Sciences 1 (3-4): 55-58.

Błaszczyk, I., Birkner, E., Gutowska, I., Romuk, E. and Chlubek, D. (2012). Influence of methionine and vitamin E on fluoride concentration in bones and teeth of rats exposed to sodium fluoride in drinking water. Biological trace element research, 146 (3), 335-339.

Dey, S. and Giri, B. (2016). Fluoride fact on human health and health problems: a review. Med Clin Rev, 2 (1), 11.

Dhar, V. and Bhatnagar, M. (2009). Physiology and toxicity of fluoride. Indian Journal of Dental Research,20 (3), 350.

Fawell, J., Bailey, K., Chilton, J., Dahi, E., Fewtrell, L. and Magara, Y. (2006). "Fluoride in Drinking-Water". World Health Organization, Geneva.

Gautam, R.., Bhardwaj., N. and Saini, Y. (2010). Fluoride accumulation by vegetables and crops grown in Nawa Tehasil of Nagaur District (Rajasthan, India). Journal of Phytology Phytophysiology. 2 (2): 80-85.

IPCS (2002). Fluorides. Environmental Health Criteria 227, UNEP, ILO and WHO, Geneva

Janiszewska, J. and Balcerzak, M. (2013). Analytical problems with the evaluation of human exposure to fluorides from tea products. Food Analytical Methods, 6(4), 1090-1098.

Kahama, R. W., Kariuki, D. N., Kariuki, H. N., and Njenga, L. W. (1997). Fluorosis in children and sources of fluoride around Lake Elementaita Region of Kenya. Fluoride, 30, 19–25.

Kanyora, A., Kinyanjui, T., Kariuki, S. and Njogu, M. (2015). Fluoride removal capacity of regenerated bone char in treatment of drinking water. Asian Journal of Natural & Applied Sciences Vol, 4, 1.

Kenya National Bureau of Statistics (2010). The 2009 Kenya population and housing census (Vol. 1). Kenya National Bureau of Statistics.

Kenya National Bureau of Statistics (2019). 2019 Kenya Population and Housing Census Volume I: Population by County and Sub-County.

Malago, J., Makoba, E., and Muzuka, A. N. (2017). Fluoride Levels in Surface and Groundwater in Africa: A Review. American Journal of Water Science and Engineering, 3(1), 1-17.

McLaughlin, M. J., Hamon, R. E., McLaren, R. G., Speir, T. W. and Rogers, S. L. (2000). A bioavailability-based rationale for controlling metal and metalloid contamination of agricultural land in Australia and New Zealand. Soil Research, 38(6), 1037-1086.

Menya, D., Maina, S. K., Kibosia, C., Kigen, N., Oduor, M., Some, F., Chumba, D., Ayuo, P., Middleton, D.R., Osano, O. and Abedi‐

Ardekani, B. (2019). Dental fluorosis and oral health in the African Esophageal Cancer Corridor: Findings from the Kenya ESCCAPE case–control study and a pan‐African perspective. International Journal of Cancer, 145(1), 99-109.

Moturi, W. K., Tole, M. P. and Davies, T. C. (2002). The contribution of drinking water towards dental fluorosis: a case study of Njoro Division, Nakuru District, Kenya. Environmental Geochemistry and Health, 24(2), 123-130.

Nair, K. R., Manji, F., and Gitonga, J. N. (1984). The occurrence and distribution of fluoride in groundwaters of Kenya.EastAfr Med J,61(7), 503–-512.

Ndambiri, H. and Rotich, E. (2018). Valuing excess fluoride removal for safe drinking water in Kenya. Water Policy, 20(5), 953-965.

Okalebo, J. R., Gathua, K. W. and Woomer, P. L. (2002). Laboratory methods of soil and plant analysis A working manual second edition. Sacred Africa, Nairobi, 21.

Okoo, J. A. (2007). Concentration levels and patterns of fluoride in groundwater resources from Kendu Bay area, Kenya (Doctoral dissertation, University of Nairobi).

Ombaka, O., Gichumbi, J. M. and Kibara, D. (2013). Evaluation of ground water and tap water quality in the villages surrounding Chuka town, Kenya. Journal of Chemical, Biological and Physical Sciences (JCBPS), 3(2), 1551.

Sarkar, C. and Pal, S. (2015). Effects of sub-acute fluoride exposure on discrete regions of rat brain associated with thyroid dysfunction: A comparative study. Int. J. Biomed. Res, 6, 647-660.

Shomar, B., Müller, G., Yahya, A., Askar, S. and Sansur, R. (2004). Fluorides in groundwater, soil and infused black tea and the occurrence of dental fluorosis among school children of the Gaza strip. Journal of water and Health, 2 (1), 23–-35.

Stogiera, A. and Buczkowska-Radlińska, J. (2015). Anthropogenic sources of fluorine–the impact on the environment and human health–a literature review. In Dental Forum (Vol. 42, No. 2, pp. 57-62).

Sujana, M. G., Pradhan, H. K. and Anand, S. (2009). Studies on sorption of some geomaterials for fluoride removal from aqueous solutions. Journal of Hazardous Materials. 161, 120-125

Teutli-Sequeira, A., Solache-Ríos, M. and Balderas-Hernández, P. (2012). Modification effects of hematite with aluminum hydroxide on the removal of fluoride ions from water. Water, Air, & Soil Pollution, 223(1), 319-327.

Wang, Mei, Xiang Li, Wen-yan He, Jin-xin Li, Yan-yuan Zhu, Yu-Liang Liao, Jin-yan Yang and Xiao-E Yang (2019). "Distribution, health risk assessment, and anthropogenic sources of fluoride in farmland soils in phosphate industrial area, southwest China." Environmental Pollution 249 (2019): 423-433.

Wiersinga, R. C. and de Jager, A. (2007). Development of commercial field vegetable production, distribution and marketing for the East African market. Literature review Kenya. LEI Wageningen UR.


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