Another parameter influencing the uptake and translocation of pharmaceuticals is
the plant per se. It is recommended to consider the plants’ age (number of days after
germination) and developmental stage (e.g. two-leaf stage, vegetative growth or
flowering/fruiting) at the time point of exposure and during the study. The plant
variety, the percentage of dry weight (root and aerial part) as well as the total lipid
content should be provided, since this information is necessary to successfully
indicate the differences on the uptake and translocation of especially lipophilic
pharmaceuticals in different plant organs or varieties.
Analytically, the extraction protocol for target compounds in the different studied
matrices should be provided along with the specific limits of detection and quantification. This is essential when authors cannot quantify a specific compound, so the
readers can understand if this is due to an analytical limitation or if the compound is
not present in that matrix. Furthermore, concentrations of pharmaceuticals in plant
tissues can be easily underestimated when only parent compounds are quantified. As
some pharmaceuticals can undergo a rapid metabolization within a few hours, it is
recommended to consider the measurement of the main metabolites, if technically
possible, to prove the uptake and translocation of such compounds.
4.1 Concluding Remarks
In many studies it became obvious that the concentration in nutrient media/soil does
not correlate with the concentration in plants, and thus it is not easy to forecast
transfer rates. Chemistry and plant physiology play important roles in the processes
involved. Moreover, interactions with soil constituents, rhizosphere processes
governed by microbes and the selective uptake mechanisms of several plant species
may be decisive for the fate of PPCP as well. The concentration of pharmaceuticals
applied in controlled experiments may affect in opposite way the BCF and TF ratio
values, since in some studies higher uptake and translocation ratios were achieved
with lower concentrations, which is highlighting the relevance of realistic environmental concentrations in uptake studies. Some plant species may also have special
features, such as Cucurbitaceae, which is known to be the only family to take up and
translocate hydrophobic PAHs. Interestingly, radish from the Brassicaceae family
stands out with consistent higher translocations, for all pharmaceutical compounds
in the analysed studies. Furthermore, it may hold true that most cationic pharmaceuticals show higher TFs in soil studies, but some will also undergo activation and
metabolization on the way, which might change their behaviour and fate. As
highlighted before, it is crucial to take all relevant plant and physicochemical
properties into consideration through every step of the scientific process that starts
with the experimental design and ends with data analysis and interpretation.
Acknowledgements This research was developed by the Water Joint Programming Initiative
(WATER-JPI) of the European Research Area (ERA-NET). We would like to thank the responsible
persons for raising the AWARE project and the Federal Office for Agriculture and Food
Uptake and Translocation of Pharmaceuticals in Plants:. . .
131
the plant per se. It is recommended to consider the plants’ age (number of days after
germination) and developmental stage (e.g. two-leaf stage, vegetative growth or
flowering/fruiting) at the time point of exposure and during the study. The plant
variety, the percentage of dry weight (root and aerial part) as well as the total lipid
content should be provided, since this information is necessary to successfully
indicate the differences on the uptake and translocation of especially lipophilic
pharmaceuticals in different plant organs or varieties.
Analytically, the extraction protocol for target compounds in the different studied
matrices should be provided along with the specific limits of detection and quantification. This is essential when authors cannot quantify a specific compound, so the
readers can understand if this is due to an analytical limitation or if the compound is
not present in that matrix. Furthermore, concentrations of pharmaceuticals in plant
tissues can be easily underestimated when only parent compounds are quantified. As
some pharmaceuticals can undergo a rapid metabolization within a few hours, it is
recommended to consider the measurement of the main metabolites, if technically
possible, to prove the uptake and translocation of such compounds.
4.1 Concluding Remarks
In many studies it became obvious that the concentration in nutrient media/soil does
not correlate with the concentration in plants, and thus it is not easy to forecast
transfer rates. Chemistry and plant physiology play important roles in the processes
involved. Moreover, interactions with soil constituents, rhizosphere processes
governed by microbes and the selective uptake mechanisms of several plant species
may be decisive for the fate of PPCP as well. The concentration of pharmaceuticals
applied in controlled experiments may affect in opposite way the BCF and TF ratio
values, since in some studies higher uptake and translocation ratios were achieved
with lower concentrations, which is highlighting the relevance of realistic environmental concentrations in uptake studies. Some plant species may also have special
features, such as Cucurbitaceae, which is known to be the only family to take up and
translocate hydrophobic PAHs. Interestingly, radish from the Brassicaceae family
stands out with consistent higher translocations, for all pharmaceutical compounds
in the analysed studies. Furthermore, it may hold true that most cationic pharmaceuticals show higher TFs in soil studies, but some will also undergo activation and
metabolization on the way, which might change their behaviour and fate. As
highlighted before, it is crucial to take all relevant plant and physicochemical
properties into consideration through every step of the scientific process that starts
with the experimental design and ends with data analysis and interpretation.
Acknowledgements This research was developed by the Water Joint Programming Initiative
(WATER-JPI) of the European Research Area (ERA-NET). We would like to thank the responsible
persons for raising the AWARE project and the Federal Office for Agriculture and Food
Uptake and Translocation of Pharmaceuticals in Plants:. . .
131