of the three plant species to antibiotics was highly variable; however, compared with
shoot and total length measurements, root elongation was consistently the most
sensitive end point. The range of phytotoxicity of the antibiotics was large, with
effect concentrations (EC 25 ) ranging from 3.9 to 10,000 μg/L. Chlortetracycline,
levofloxacin and sulfamethoxazole were the most phytotoxic antibiotics, with significant effects of chlortetracycline observed as low as 1,000 μg/L and EC 25 s ranging
from 33 to 193 μg/L which the authors noted are lower than reported environmental
concentrations of chlortetracycline in swine manure [122]. Interestingly, whilst plant
growth was affected, plant germination was insensitive to the antibiotics, with no
significant decreases up to the highest treatment concentration (10,000 μg/L).
Phytotoxicity studies have also been carried out using classes of pharmaceuticals
other than antibiotics. For example, significant effects (P 0.01) on plant dry weight
across a suite of maize hybrids have been observed in response to exposure to
paracetamol, ibuprofen and diclofenac by Hammad et al. [123]. Exposure to paracetamol in particular resulted in significant effects, with plant dry weight decreasing
in a linear fashion with increasing paracetamol concentrations. Interestingly, effects
were observed to vary amongst the different maize hybrids with plant dry weight
decreasing from 204.5 to 172.0 g plant
À1 in hybrid ICI 339, whereas a smaller
decrease in dry weight was observed in the Syngenta 7720 hybrid from 169.0 to
166.3 g plant
À1 . The application of paracetamol was also observed to significantly
( p < 0.05) decrease grains’ yield by up to 50% (75.8 vs. 37.5) in the sensitive maize
hybrid (Syngenta 7720), with the smallest decrease in grain weight 34%
(81.0 vs. 53.3) found in the resistant maize hybrids.
Detectable carbamazepine concentrations were found in edible zucchini
(Cucurbita pepo) fruit from 1 to 20 μg/kg by Knight et al. [124], but this study
also revealed novel insights into the effect of carbamazepine accumulation on
C. pepo fruiting. Female C. pepo flowers were also unable to set fruit when
translocation of carbamazepine resulted in leaf concentrations !14 mg/kg. These
findings may have implications for future agricultural productivity in areas where
reclaimed wastewater containing pharmaceuticals is a source of irrigation.
In the plant uptake studies by Boxall et al. [57], a decline in plant growth was
observed for the veterinary medicine exposures, phenylbutazone, oxytetracycline
and enrofloxacin. However, from a review of published literature, the extent to
which a pharmaceutical impact on plant growth appears to be dependent on both
the plant and physiochemical properties of the pharmaceutical compound. As such,
Boxall et al. [57] observed that, whilst effects were seen in three exposures, there is
was no effect of florfenicol, levamisole, trimethoprim and diazinon on plant weight
data at the time of harvest.
In fact, positive effects on plant growth parameters in response to pharmaceutical
exposure have been reported in recent scientific literature. Effects upon germination,
development, growth and physiology of radish and lettuce, after exposure to
non-steroidal anti-inflammatory drugs (NSAIDs) at environmentally relevant concentrations, were evaluated by Schmidt and Redshaw [125]. An increase in
R. sativus root length was observed upon exposure to tolfenamic acid, and although
not statistically significant, meclofenamic acid sodium-exposed R. sativus had
longer median root lengths than observed under mefenamic acid and the solvent
206
L. J. Carter et al.
shoot and total length measurements, root elongation was consistently the most
sensitive end point. The range of phytotoxicity of the antibiotics was large, with
effect concentrations (EC 25 ) ranging from 3.9 to 10,000 μg/L. Chlortetracycline,
levofloxacin and sulfamethoxazole were the most phytotoxic antibiotics, with significant effects of chlortetracycline observed as low as 1,000 μg/L and EC 25 s ranging
from 33 to 193 μg/L which the authors noted are lower than reported environmental
concentrations of chlortetracycline in swine manure [122]. Interestingly, whilst plant
growth was affected, plant germination was insensitive to the antibiotics, with no
significant decreases up to the highest treatment concentration (10,000 μg/L).
Phytotoxicity studies have also been carried out using classes of pharmaceuticals
other than antibiotics. For example, significant effects (P 0.01) on plant dry weight
across a suite of maize hybrids have been observed in response to exposure to
paracetamol, ibuprofen and diclofenac by Hammad et al. [123]. Exposure to paracetamol in particular resulted in significant effects, with plant dry weight decreasing
in a linear fashion with increasing paracetamol concentrations. Interestingly, effects
were observed to vary amongst the different maize hybrids with plant dry weight
decreasing from 204.5 to 172.0 g plant
À1 in hybrid ICI 339, whereas a smaller
decrease in dry weight was observed in the Syngenta 7720 hybrid from 169.0 to
166.3 g plant
À1 . The application of paracetamol was also observed to significantly
( p < 0.05) decrease grains’ yield by up to 50% (75.8 vs. 37.5) in the sensitive maize
hybrid (Syngenta 7720), with the smallest decrease in grain weight 34%
(81.0 vs. 53.3) found in the resistant maize hybrids.
Detectable carbamazepine concentrations were found in edible zucchini
(Cucurbita pepo) fruit from 1 to 20 μg/kg by Knight et al. [124], but this study
also revealed novel insights into the effect of carbamazepine accumulation on
C. pepo fruiting. Female C. pepo flowers were also unable to set fruit when
translocation of carbamazepine resulted in leaf concentrations !14 mg/kg. These
findings may have implications for future agricultural productivity in areas where
reclaimed wastewater containing pharmaceuticals is a source of irrigation.
In the plant uptake studies by Boxall et al. [57], a decline in plant growth was
observed for the veterinary medicine exposures, phenylbutazone, oxytetracycline
and enrofloxacin. However, from a review of published literature, the extent to
which a pharmaceutical impact on plant growth appears to be dependent on both
the plant and physiochemical properties of the pharmaceutical compound. As such,
Boxall et al. [57] observed that, whilst effects were seen in three exposures, there is
was no effect of florfenicol, levamisole, trimethoprim and diazinon on plant weight
data at the time of harvest.
In fact, positive effects on plant growth parameters in response to pharmaceutical
exposure have been reported in recent scientific literature. Effects upon germination,
development, growth and physiology of radish and lettuce, after exposure to
non-steroidal anti-inflammatory drugs (NSAIDs) at environmentally relevant concentrations, were evaluated by Schmidt and Redshaw [125]. An increase in
R. sativus root length was observed upon exposure to tolfenamic acid, and although
not statistically significant, meclofenamic acid sodium-exposed R. sativus had
longer median root lengths than observed under mefenamic acid and the solvent
206
L. J. Carter et al.