# Update on Endemic Fluorosis in a Region of Europe (Tenerife, Canary Islands)
## 3 Results and Discussion

Table 2: The fluoride mean concentrations, standard deviation and confidence interval (CI 95%) of the water supply samples for each of the districts, municipalities and regions of the island of Tenerife. Figure 4: Graph of fluoride mean concentrations of the water supply samples for each municipality of the island of Tenerife. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Region** & **Municipality** & **District** & \begin{tabular}{c} **[F\({}^{-}\)] mg/L** \\ **District** \\ \end{tabular} & \begin{tabular}{c} **[F\({}^{-}\)] mg/L** \\ **Municipality** \\ \end{tabular} & \begin{tabular}{c} **[F\({}^{-}\)] mg/L** \\ **Municipality** \\ \end{tabular} & \
\begin{tabular}{c} **CI (95\%)** \\ **Region** \\ \end{tabular} &
\begin{tabular}{c} **[F\({}^{-}\)] mg/L** \\ **Region** \\ \end{tabular} \\ \hline \multirow{4}{*}{**Candelaria**} & \multicolumn{2}{c}{Casco upano} & \multicolumn{2}{c}{0.57} & \multirow{4}{*}{0.94 \(\pm\) 0.71} & \multirow{4}{*}{0.94 \(\pm\) 0.71} & \multirow{4}{*}{0.94 \(\pm\) 0.01} & \multirow{4}{*}{0.94 \(\pm\) 0.01} \\ \cline{2-3} \cline{5-8}  & Las Cuevecitas & 1.30 & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{La Hidalga} & 0.94 & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 0.93 & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Puertito de Gümar} & 1.41 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 0.98 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Los Roques de Fsnia} & 2.05 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 2.46 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Abades} & 0.95 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 1.22 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Granadilla de} & \multicolumn{2}{c}{San Isidro} & 0.39 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Abona} & \multicolumn{2}{c}{Casco upano} & 2.06 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Las Chafiras} & 0.46 & & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Abona} & \multicolumn{2}{c}{Casco upano} & 1.58 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Las Escalona} & 2.57 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 2.08 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Las Américas} & 0.05 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 0.86 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Costa Adeje} & 0.02 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 0.71 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Alcalá} & 0.91 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Casco upano} & 2.33 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Puerto Santiago del} & 0.45 & & & & & \\ \cline{2-3} \cline{5-8}  & \multicolumn{2}{c}{Telede} & \multicolumn{2}{c}{Casco upano} & 1.87 & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._Our analysis revealed that 55% of municipalities on the island of Tenerife have fluoride concentrations above the parametric level established in European and Spanish legislation (1.5 mg/L) [70]. This fact confirms the permanence of this public health problem of endemic fluorosis that has been demonstrated since 1983 [76]. A statistical analysis confirmed significant differences in fluoride content between the northern and southern zones (\(p\) = 0.0015). This was not the case between the northern and metropolitan zones (\(p\) = 0.5858), nor between the metropolitan and southern zones (\(p\) = 0.3435). This aligns with the historical trend, showing a gradual increase in fluoride concentrations, with the lowest concentrations being found in the southern region, the highest in the northern region and intermediate concentrations being found in the metropolitan region (Table 2). The only region that complies with the official parameters is the south of Tenerife.