non-steroidal anti-inflammatory drugs (NSAIDs), lipid regulators, β-blockers as well
as antibiotics. Whilst 14 days of exposure to some of the blood lipid regulators, the
β-blockers and antibiotics did not result in observed acute toxicity, the NSAIDs and
some blood lipid-regulating pharmaceuticals were acutely toxic (lethality) to earthworms (E. fetida) [135]. The greatest toxicity was reported for ibuprofen (lethal
concentration, LC 50 ¼ 64.80 mg/kg) followed by diclofenac (LC 50 ¼ 90.49 mg/kg)
and simvastatin (LC 50 ¼ 92.70 mg/kg). The lethal concentrations reported for the
pharmaceuticals in this study far exceed environmentally relevant concentrations
reported for soils irrigated with reclaimed wastewater or amended with biosolids.
Similar conclusions were reached in a study of the ecotoxicity of biosolids-borne
triclocarban (disinfectant) in earthworms (E. fetida, [138]). The LC 50 for triclocarban
was greater than 40 mg/kg for biosolid-amended soils, which far exceeds the
concentration of triclocarban previously reported in soils amended with biosolids.
In the same study, the researchers determined that triclocarban in biosolids, even at
concentrations exceeding the native concentration, did not affect common measures
of microbial activity in soil, soil respiration and ammonification.
Based on published research to date, exposure to individual pharmaceuticals at
environmentally relevant concentrations is unlikely to result in earthworm toxicity.
However, reclaimed wastewater and biosolids contain a complex mixture of pharmaceuticals together with other organic and inorganic contaminants [2, 3]. A recent
study of the ecotoxicity of land-applied biosolids found biosolids to be acutely toxic
to earthworms (E. fetida) even at environmental relevant application rates to agricultural soils [139]. End points measured in the study included earthworm survival
and measures of earthworm reproduction. Biosolids at application rates as low as 1%
by mass in soil resulted in a significant reduction in adult earthworm survival and
complete lethality at 3 and 4% biosolids in soil. Similar results have been reported in
by others [140]. The production of juvenile earthworms and cocoons (measures of
reproductive success) was also reduced with increasing exposure to biosolids from
1% up to 4% in soil [139]. More work is needed to elucidate if the toxic effects
observed in these studies were the result of synergistic interactions of pharmaceuticals and other contaminants.
A small number of field studies have evaluated the effects of pharmaceuticals on
soil invertebrates, with research largely focussed on laboratory tests. In one such
study, the abundance of earthworms and springtails in soil beneath the dung from
cattle treated with ivermectin was evaluated over 12 months [141]. Whilst ivermectin was detected in the soil beneath the dung pats (<0.006 mg/kg in months 5–7),
earthworms (Lumbricidae) and springtails (Collembola) were found to be abundant
and generally species rich across the evaluated sites, leading the authors to conclude
that ivermectin had little effect on the soil invertebrate populations. Like earthworms, springtails are common small arthropod widely distributed in soils around
the globe. However, information concerning the toxicity of pharmaceuticals to
springtails is even more limited than for earthworms. One of the most comprehensive multispecies studies reported effects of ivermectin (survival and reproduction)
across three species, the earthworm Eisenia fetida, the springtail Folsomia candida
and the predatory mite Hypoaspis aculeifer [142]. Survival and reproduction of
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L. J. Carter et al.
as antibiotics. Whilst 14 days of exposure to some of the blood lipid regulators, the
β-blockers and antibiotics did not result in observed acute toxicity, the NSAIDs and
some blood lipid-regulating pharmaceuticals were acutely toxic (lethality) to earthworms (E. fetida) [135]. The greatest toxicity was reported for ibuprofen (lethal
concentration, LC 50 ¼ 64.80 mg/kg) followed by diclofenac (LC 50 ¼ 90.49 mg/kg)
and simvastatin (LC 50 ¼ 92.70 mg/kg). The lethal concentrations reported for the
pharmaceuticals in this study far exceed environmentally relevant concentrations
reported for soils irrigated with reclaimed wastewater or amended with biosolids.
Similar conclusions were reached in a study of the ecotoxicity of biosolids-borne
triclocarban (disinfectant) in earthworms (E. fetida, [138]). The LC 50 for triclocarban
was greater than 40 mg/kg for biosolid-amended soils, which far exceeds the
concentration of triclocarban previously reported in soils amended with biosolids.
In the same study, the researchers determined that triclocarban in biosolids, even at
concentrations exceeding the native concentration, did not affect common measures
of microbial activity in soil, soil respiration and ammonification.
Based on published research to date, exposure to individual pharmaceuticals at
environmentally relevant concentrations is unlikely to result in earthworm toxicity.
However, reclaimed wastewater and biosolids contain a complex mixture of pharmaceuticals together with other organic and inorganic contaminants [2, 3]. A recent
study of the ecotoxicity of land-applied biosolids found biosolids to be acutely toxic
to earthworms (E. fetida) even at environmental relevant application rates to agricultural soils [139]. End points measured in the study included earthworm survival
and measures of earthworm reproduction. Biosolids at application rates as low as 1%
by mass in soil resulted in a significant reduction in adult earthworm survival and
complete lethality at 3 and 4% biosolids in soil. Similar results have been reported in
by others [140]. The production of juvenile earthworms and cocoons (measures of
reproductive success) was also reduced with increasing exposure to biosolids from
1% up to 4% in soil [139]. More work is needed to elucidate if the toxic effects
observed in these studies were the result of synergistic interactions of pharmaceuticals and other contaminants.
A small number of field studies have evaluated the effects of pharmaceuticals on
soil invertebrates, with research largely focussed on laboratory tests. In one such
study, the abundance of earthworms and springtails in soil beneath the dung from
cattle treated with ivermectin was evaluated over 12 months [141]. Whilst ivermectin was detected in the soil beneath the dung pats (<0.006 mg/kg in months 5–7),
earthworms (Lumbricidae) and springtails (Collembola) were found to be abundant
and generally species rich across the evaluated sites, leading the authors to conclude
that ivermectin had little effect on the soil invertebrate populations. Like earthworms, springtails are common small arthropod widely distributed in soils around
the globe. However, information concerning the toxicity of pharmaceuticals to
springtails is even more limited than for earthworms. One of the most comprehensive multispecies studies reported effects of ivermectin (survival and reproduction)
across three species, the earthworm Eisenia fetida, the springtail Folsomia candida
and the predatory mite Hypoaspis aculeifer [142]. Survival and reproduction of
208
L. J. Carter et al.