3.2 Data Analysis
3.2.1 Neutral Compounds
Neutral organic compounds were identified as having higher membrane penetration
than ionized substances [140]. Therefore, it is expected, that these molecules can be
taken up and translocated easily by transpiration via the xylem [51], resulting in
TFs > BCFs. For compounds like meprobamate, caffeine and carbamazepine and,
additionally, estrone, oxazepam and temazepam (in soil assays), this pattern was
observed (Tables 1 and 2). Figure 4 shows that many observations and studies were
made on the uptake and translocation of caffeine and carbamazepine, reflecting a
TF > BCF, which clearly underlines their validity. However, this pattern is not
clearly detected for the whole group of compounds.
Looking at the data in detail, triclocarban (antibacterial) stands out with an
average BCF of 31.4, as a result from data reported in Sun and co-authors [109]
and Wu and co-authors [110] (Table 1). In total, these two studies had nine
observations, and none of them had TF higher than 0.08 (Fig. 4). BCFs
(18.9–32.4) obtained by Wu and co-workers [110] for spinach and lettuce, when
exposed for 21 days at two different concentrations (5 and 0.5 μg/L), were similar,
and also Sun and co-authors [109] observed a relatively high BCF (12.6) when
cucumber was exposed for 7 days to a concentration of 5.0 μg/L. Therefore, the
Table 2 Chemical properties of neutral pharmaceuticals, as well as the average BCFs and TFs
calculated per compound in soil studies
Compounds
log
K OW
pH
pKa
log
D OW
BCF TF
Authors
Average values
Analgesic
Acetaminophen
0.46
8.10 0.00
0.09
0.01
0.34 [102]
Antibacterial
Triclocarban
4.34
6.42 0.00
5.23
0.02
0.50 [121]
Antibiotic
Sulfamethoxazole
0.89
5.67 0.00 À0.06
0.96
0.58 [11, 112, 122, 123]
Anticonvulsant
Carbamazepine
2.45
7.03 0.00
3.64
0.62
3.57 [11, 102, 112, 123–
128]
Hormone
17α-ethinylestradiol
3.67
6.60 0.00
4.94
0.61
0.06 [129]
Estrone
3.13
8.10 0.00
4.23
0.00
2.45 [20]
Psychotropic drug
Oxazepam
2.24
6.30 0.00
3.42
0.04 17.15 [130]
Temazepam
2.19
6.30 0.00
4.71
0.01
5.99 [130]
Stimulant
Caffeine
À0.07
7.87 0.00
0.95
0.23 20.03 [102, 126, 127]
Symbols: na, means not available; nd, means not detected
Uptake and Translocation of Pharmaceuticals in Plants:. . .
121
3.2.1 Neutral Compounds
Neutral organic compounds were identified as having higher membrane penetration
than ionized substances [140]. Therefore, it is expected, that these molecules can be
taken up and translocated easily by transpiration via the xylem [51], resulting in
TFs > BCFs. For compounds like meprobamate, caffeine and carbamazepine and,
additionally, estrone, oxazepam and temazepam (in soil assays), this pattern was
observed (Tables 1 and 2). Figure 4 shows that many observations and studies were
made on the uptake and translocation of caffeine and carbamazepine, reflecting a
TF > BCF, which clearly underlines their validity. However, this pattern is not
clearly detected for the whole group of compounds.
Looking at the data in detail, triclocarban (antibacterial) stands out with an
average BCF of 31.4, as a result from data reported in Sun and co-authors [109]
and Wu and co-authors [110] (Table 1). In total, these two studies had nine
observations, and none of them had TF higher than 0.08 (Fig. 4). BCFs
(18.9–32.4) obtained by Wu and co-workers [110] for spinach and lettuce, when
exposed for 21 days at two different concentrations (5 and 0.5 μg/L), were similar,
and also Sun and co-authors [109] observed a relatively high BCF (12.6) when
cucumber was exposed for 7 days to a concentration of 5.0 μg/L. Therefore, the
Table 2 Chemical properties of neutral pharmaceuticals, as well as the average BCFs and TFs
calculated per compound in soil studies
Compounds
log
K OW
pH
pKa
log
D OW
BCF TF
Authors
Average values
Analgesic
Acetaminophen
0.46
8.10 0.00
0.09
0.01
0.34 [102]
Antibacterial
Triclocarban
4.34
6.42 0.00
5.23
0.02
0.50 [121]
Antibiotic
Sulfamethoxazole
0.89
5.67 0.00 À0.06
0.96
0.58 [11, 112, 122, 123]
Anticonvulsant
Carbamazepine
2.45
7.03 0.00
3.64
0.62
3.57 [11, 102, 112, 123–
128]
Hormone
17α-ethinylestradiol
3.67
6.60 0.00
4.94
0.61
0.06 [129]
Estrone
3.13
8.10 0.00
4.23
0.00
2.45 [20]
Psychotropic drug
Oxazepam
2.24
6.30 0.00
3.42
0.04 17.15 [130]
Temazepam
2.19
6.30 0.00
4.71
0.01
5.99 [130]
Stimulant
Caffeine
À0.07
7.87 0.00
0.95
0.23 20.03 [102, 126, 127]
Symbols: na, means not available; nd, means not detected
Uptake and Translocation of Pharmaceuticals in Plants:. . .
121