# Assessment of Human Pharmaceuticals in Drinking Water Catchments, Tap and Drinking Fountain Waters
## 3 Results and Discussion
### Occurrence and Comparison with Other Studies  
In the 97 water samples analyzed none of the drinking water catchments (surface and groundwater), drinking fountains and tap water samples presented concentrations above the MDLs. The drinking water fountains' sampling was performed in a low population density region and with low contamination pressure, which can justify the observed results. As for the surface and groundwaters' catchments for drinking waters, with the exception of Boavista catchment, they were also located far from high population density and contaminated areas. This seems to be a good option for the location of drinking water catchments. Naturally, that if the catchments presented concentrations below the MDLs, as expected, the drinking waters obtained from these catchments presented similar results. When observing the concentration of pharmaceuticals in other water matrices provided by other studies, it is possible to identify decreasing levels of contamination in WWIs, WWEs and surface waters [3; 21]. Generally, observing previous Portuguese results, compounds are found in WWI with much higher concentration values than in WWE [3; 19; 25]. In both matrices, WWIs and WWEs, 100% detection frequency was observed. The highest average and concentration found in WWIs were 41 and 150 \(\upmu\)g L\({}^{-1}\), respectively; as in WWEs, the values were of 1.8 and 33 \(\upmu\)g L\({}^{-1}\), respectively, both for PARA [19]. Performing the environmental risk assessment, we can observe that the WWEs still pose a threat to aquatic ecosystems [3; 19; 26]. The range of pharmaceutical concentrations observed in Portuguese rivers was considerably lower than the ones recorded in the WWEs, with detection frequencies of 27.8% and average (7.78-39.21 ng L\({}^{-1}\)) and maximum (69.15 ng L\({}^{-1}\)) concentration in the low ng L\({}^{-1}\) levels [21]. In surface waters, several compounds were not detected, namely the hormones E1, E2 and EE2, NSAIDs IBU and NAP and the antibiotic CIP. These concentrations in surface waters appear to be primarily related to the river flow rates, suggesting that, the dilution factor is the main accountable for pharmaceutical river concentrations [21]. The European Medicines Agency (EMA) Guideline on Environmental Risk Assessment (ERA) suggest the use of a factor (0.25) to derive the concentrations in groundwaters from surface waters [22; 23]. Notably, the obtained results showed that the concentrations in groundwater, below the MDLs (<5.45 ng L\({}^{-1}\)), were considerably lower than those obtained by the use of the EMA factor in surface water concentrations (averages of 1.95-9.80 ng L\({}^{-1}\)), questioning the accuracy of this factor. Our results show that the concentrations in groundwaters must be more than 7 times lower (factor of 0.14) than the ones in surface waters. Regarding the pharmaceutical with the highest concentrations in several water matrices, namely PARA, one can compare the observed levels: 150 \(\upmu\)g L\({}^{-1}\) in WWI, 32 \(\upmu\)g L\({}^{-1}\) in WWE, 69.15 ng L\({}^{-1}\) in surface waters and <3.57 ng L\({}^{-1}\) in the present study. These values imply a reduction of 78.7% from WWIs to WWEs and of 99.8% from WWEs to surface water. Moreover, the concentration decreases from WWI to this study more than 99.99% [3; 19; 21; 24]. The results found in this study were consistent with those previously reported in Portuguese drinking and groundwaters by other authors with concentrations ranging from 0.005 to 23.8 ng L\({}^{-1}\) and where hormones were also not detected [25; 26; 27]. Overall, the levels of pharmaceuticals detected in drinking water catchments and drinking water were generally below 50 ng L\({}^{-1}\)[15; 28; 29; 30]. In fact, the concentrations reported by other authors confirm effectively low concentrations values in these water types. Therefore, it is unlikely that pharmaceuticals pose significant threats to human health at the concentrations that may occur in drinking waters [31; 32].