# Update on Endemic Fluorosis in a Region of Europe (Tenerife, Canary Islands)
## 3 Results and Discussion
To contextualize this issue, we present a historical overview of fluoride concentrations in Tenerife's water supply (Tables 3 and 4). Table 3 shows fluoride concentrations in different galleries in the municipality of La Guencha from 1976 to 1997. In the 1990s, most of these galleries ceased to be used due to loss of flow, leaving the Barranco de Vergara gallery as the main one, with a current flow of 1056 m\({}^{3}\)/h and three conduits that try to supply a large part of the island [72; 77; 78]. Table 4 summarizes the fluoride levels detected in various studies carried out in the island's water supply from 1984 to the present. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Municipality**} & \multicolumn{8}{c}{**Years**} \\ \cline{2-11}  & **1983 \({}^{\text{a}}\)** & **1986 \({}^{\text{b}}\)** & **1987 \({}^{\text{c}}\)** & **1995 \({}^{\text{d}}\)** & **1997 \({}^{\text{e}}\)** & **1998–** & **2000 \({}^{\text{f}}\)** & **2009 \({}^{\text{g}}\)** & **2015 \({}^{\text{h}}\)** & **2020 \({}^{\text{l}}\)** & **2023 \({}^{\text{j}}\)** \\ \hline \multirow{2}{*}{**El-Tanque**} & 0.31– & \multirow{2}{*}{-} & \multirow{2}{*}{0.65} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{\(>\)2.7} & \multirow{2}{*}{\(>\)4} & 0.35– & 0.34– & 2.13 \(\pm\) \\  & 4.93 & & & & & & 4.38 & 2.95 & & 0.01 \\ \hline \multirow{2}{*}{**Garachico**} & 0.17– & \multirow{2}{*}{-} & \multirow{2}{*}{0.35} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{\(>\)2.7} & \multirow{2}{*}{1.5–4} & 0.47–2.5 & 1.33– & - & 3.32 \(\pm\) \\  & 5.12 & & & & & & 3.05 & & 0.78 \\ \hline \multirow{2}{*}{**Icod-de-los-Vinos**} & 0.25– & \multirow{2}{*}{-} & 5.20– & 4.38 \(\pm\) & \multirow{2}{*}{-} & \multirow{2}{*}{\(>\)2.7} & \multirow{2}{*}{1.5–4} & 2.22– & 2.05– & 4.59 \(\pm\) \\  & 5.60 & & & & & & 3.94 & 3.12 & 2.75 & 2.52 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Historical review of fluoride concentration (mg/L) in the water supply of the municipalities of the island of Tenerife. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Gallery**} & \multicolumn{8}{c}{**Year**} \\ \cline{2-7}  & **1976** & **1981** & **1984** & **1986** & **1995** & **1997** \\ \hline
**Barranco Vergara** & 6.41 & 7.80 & 8.00 & 9.40 & 10.20 & 10.00 \\ \hline
**El Fronton** & 4.72 & 5.10 & - & 4.40 & - & - \\ \hline
**Pinalete** & 4.18 & - & - & 4.30 & - & - \\ \hline
**Sta. Teresa** & 3.96 & 5.00 & - & 3.90 & - & - \\ \hline
**Los Palomos** & 3.25 & 5.98 & - & 4.30 & - & - \\ \hline
**El Porvenir** & 2.58 & 3.10 & - & 3.10 & - & - \\ \hline
**Derriscadero** & 2.54 & 2.00 & - & 3.30 & - & - \\ \hline
**La Esperanza** & 0.57 & - & - & - & - & - \\ \hline
**Fuente Pedro \({}^{\text{*}}\)** & - & 5.20 & 5.00 & - & - & - \\ \hline
**Bilbao \({}^{\text{*}}\)** & - & 4.10 & 3.50 & - & - & - \\ \hline
**El Partido \({}^{\text{*}}\)** & - & 2.90 & 2.75 & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Fluoride concentrations (mg/L) in the water of some galleries in the municipality of La Guencha between 1976 and 1997 [79; 80]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Municipality**} & \multicolumn{10}{c}{**Years**} \\ \cline{2-13}  & **1983 a** & **1986 b** & **1987 c** & **1995 d** & **1997 e** & **1998-2000 f** & **2006 f** & **2009 g** & **2015 h** & **2020 i** & **2023 j** \\ \hline
**Buenavista** & \begin{tabular}{c} 0.43- \\ 4.53 \\ \end{tabular}  & - & 0.35 & - & - & \(>\)2.7 & \(>\)4 & \ \begin{tabular}{c} 1.11- \\ 1.16 \\ \end{tabular}  & \begin{tabular}{c} 1.00- \\ 6.70 \\ \end{tabular}  & - & - \\ \hline
**Los-Silos** & \begin{tabular}{c} 0.20- \\ 0.62 \\ \end{tabular}  & - & 0.50 & - & - & \(>\)2.7 & 1.5–4 & 1.05 & \ \begin{tabular}{c} 0.96- \\ 3.05 \\ \end{tabular}  & - & \begin{tabular}{c} 2.41 \(\pm\) \\ 1.25 \\ \end{tabular}  \\ \hline
**La-Guancha** & \begin{tabular}{c} 2.75- \\ 8.00 \\ \end{tabular}  & 3.90 & 4.10 & \begin{tabular}{c} 5.11 \(\pm\) \\ 1.02 \\ \end{tabular}