Fluoride concentration in ground water and prevalence of dental fluorosis in Ethiopian Rift Valley: systematic review and meta-analysis

BACKGROUND: The concentration of fluoride in ground drinking water greater than the world health organization standard value imposes a serious health, social and economic problem in developing countries. In the Ethiopian Rift Valley where deep wells are the major source of drinking water, high fluoride level is expected. Though many epidemiological studies on fluoride concentration and its adverse effects have been conducted in the region, the result is highly scattered and needs systematically summarized for better utilization. OBJECTIVE: This research is aimed at estimating the pooled level of fluoride concentration in ground drinking water and the prevalence of dental fluorosis among Ethiopian rift valley residences. METHODS: Cochrane library, MEDLINE/PubMed and Google scholar databases were searched for studies reporting the mean concentration of fluoride in ground water and prevalence of dental fluorosis in Ethiopian Rift valley. Search terms were identified by extracting key terms from reviews and selected relevant papers and review medical subject headings for relevant terms. RESULTS: The mean fluoride level in ground water and the prevalence of dental fluorosis were pooled from eleven and nine primary studies conducted in Ethiopian Rift Valley respectively. The pooled mean level of fluoride in ground water therefore was 6.03 mg/l (95% CI; 4.72–7.72, p < 0.001) and the pooled prevalence of dental fluorosis among residents in Ethiopian rift valley was 32% (95% CI: 25, 39%, p < 0.001), 29% (95% CI: 22, 36%, p < 0.001) and 24% (95% CI: 17, 32%, p < 0.001 for mild, moderate and sever dental fluorosis respectively. The overall prevalence of dental fluorosis is 28% (95% CI, 24, 32%, p < 0.001). CONCLUSIONS: Though, the concentration level varies across different part of the rift valley region, still the level of fluoride in ground drinking water is greater than the WHO standard value (1.5 mg/l). Relatively high-level pooled prevalence of dental fluorosis was also seen in Ethiopian rift valley. Therefore, further studies covering the temperature, exposure time and other intake path ways with large sample size is recommended. Interventional projects should be implemented to decrease the concentration of fluoride in the ground drinking water source.