Due to their chemical properties, a topic that will be also discussed further in this
chapter, pharmaceutical residues, metabolites and TPs might be adsorbed to soil
particles and taken up by plants [6]. In order to be able to estimate the effects not
only on biota but also on human health, an understanding of the absorption and
transport processes in plants is of ample relevance.
This chapter will provide readers with an overview of the most important uptake
mechanisms in plants, in addition to the transport of pharmaceutical compounds
through the plant vascular system. Concepts will be resumed from soil and chemical
properties ending up in plant biotransformation and sequestration mechanisms and
environmental factors that can influence the pharmaceuticals’ uptake.
This article will cover the main pharmaceutical groups, i.e. antibiotics, hormones,
analgesics, anti-inflammatory, lipid regulator agents, antidiabetic, anticonvulsants,
stimulants, psychotropic drugs and antihypertensives (e.g. beta-blockers, calcium
channel- or angiotensin receptor blockers) since these compound classes are in
continuous debit into the environment and due to their chemical characteristics
that make them prone to plant uptake.
Data on pharmaceutical uptake and translocation published from year 2013 on
were analysed to take conclusions based on different experiments and conditions.
2 Which Factors Can Influence the Uptake
of Pharmaceuticals by Plant Roots?
Soil properties, like ionic strength, pH and organic matter (OM) content, are
determining factors in the fate of emergent compounds (as pharmaceuticals) in
soil-plant systems. OM is an important sorbent for pharmaceuticals, which changes
their bioavailability/bioaccessibility for root uptake [7, 8] (see Fig. 1). According to
Miller and co-authors [9], polar and ionizable pharmaceuticals can engage in
interactions beyond hydrophobic partitioning, including electron donor-acceptor
interactions, cation and anion exchange, protonation, water bridging, cation bridging
and surface complexation. Moreover, for ionizable compounds, several physicochemical properties strongly influence the degree of association with soil particles.
Abiotic transformations like redox reactions may occur in the clay fraction
through reactive mineral phases and influence the molecule’s integrity. Photolysis
can likewise be involved in processes close to soil surfaces, but it has a lower
relevance due to strong light attenuation deeper in soils [9].
Synergistic effects between different pharmaceuticals can also play an important
role. Especially, when crops are irrigated with treated wastewater, plants are not only
exposed to one but to a cocktail of pharmaceuticals and other compounds. The
co-occurrence of carbamazepine and lamotrigine in crops showed that synergistic
effects enhanced the uptake of lamotrigine when carbamazepine was present, but the
uptake of carbamazepine was not affected in presence of lamotrigine in cucumber
plants (Cucumis sativus) grown under hydroponic conditions [10]. Moreover, the
Uptake and Translocation of Pharmaceuticals in Plants:. . .
105
chapter, pharmaceutical residues, metabolites and TPs might be adsorbed to soil
particles and taken up by plants [6]. In order to be able to estimate the effects not
only on biota but also on human health, an understanding of the absorption and
transport processes in plants is of ample relevance.
This chapter will provide readers with an overview of the most important uptake
mechanisms in plants, in addition to the transport of pharmaceutical compounds
through the plant vascular system. Concepts will be resumed from soil and chemical
properties ending up in plant biotransformation and sequestration mechanisms and
environmental factors that can influence the pharmaceuticals’ uptake.
This article will cover the main pharmaceutical groups, i.e. antibiotics, hormones,
analgesics, anti-inflammatory, lipid regulator agents, antidiabetic, anticonvulsants,
stimulants, psychotropic drugs and antihypertensives (e.g. beta-blockers, calcium
channel- or angiotensin receptor blockers) since these compound classes are in
continuous debit into the environment and due to their chemical characteristics
that make them prone to plant uptake.
Data on pharmaceutical uptake and translocation published from year 2013 on
were analysed to take conclusions based on different experiments and conditions.
2 Which Factors Can Influence the Uptake
of Pharmaceuticals by Plant Roots?
Soil properties, like ionic strength, pH and organic matter (OM) content, are
determining factors in the fate of emergent compounds (as pharmaceuticals) in
soil-plant systems. OM is an important sorbent for pharmaceuticals, which changes
their bioavailability/bioaccessibility for root uptake [7, 8] (see Fig. 1). According to
Miller and co-authors [9], polar and ionizable pharmaceuticals can engage in
interactions beyond hydrophobic partitioning, including electron donor-acceptor
interactions, cation and anion exchange, protonation, water bridging, cation bridging
and surface complexation. Moreover, for ionizable compounds, several physicochemical properties strongly influence the degree of association with soil particles.
Abiotic transformations like redox reactions may occur in the clay fraction
through reactive mineral phases and influence the molecule’s integrity. Photolysis
can likewise be involved in processes close to soil surfaces, but it has a lower
relevance due to strong light attenuation deeper in soils [9].
Synergistic effects between different pharmaceuticals can also play an important
role. Especially, when crops are irrigated with treated wastewater, plants are not only
exposed to one but to a cocktail of pharmaceuticals and other compounds. The
co-occurrence of carbamazepine and lamotrigine in crops showed that synergistic
effects enhanced the uptake of lamotrigine when carbamazepine was present, but the
uptake of carbamazepine was not affected in presence of lamotrigine in cucumber
plants (Cucumis sativus) grown under hydroponic conditions [10]. Moreover, the
Uptake and Translocation of Pharmaceuticals in Plants:. . .
105