damage to DNA macromolecules using the comet assay, and it revealed increasing
damage over time and dose [54]. Another particular phthalate, di-(2-ethylhexyl)
phthalate (DEHP), was spiked in natural soil (1, 3, 9 and 27 mg kg
À1 ), and several
biomarkers were evaluated in E. fetida coelomocytes. Some parameters increased,
SOD, LPO, MT, HSP70 and genotoxicity (comet assay), while others decreased:
POD, LMS (NRR) and mitochondrial membrane potential difference in relation to
concentration and over time [55]. The authors proposed a precautionary level of
3 mg kg
À1 for potential risk of phthalates in soils (based on DEHP results).
Assessment of toxicity due to polyethylene (PE) pellet (250–1,000 μm) exposure
in E. andrei was conducted at a wide range of PE concentrations (max 1 mg kg
À1 ) in
soil for 28 days [56]. Damage in gut tissue was revealed at all concentrations in a
dose-dependent manner as well as toxicity of the immune system. More recently, the
same authors evaluated low-density polyethylene microplastics (MP) toxicity in the
same model species, following the same standardised protocol but considering
additional oxidative stress parameters (GST and LPO) as well as the anaerobic
metabolism marker (LDH) as endpoints [57]. The authors concluded that MP
exposure caused oxidative stress and changes in energy metabolism more significantly after soil exposures over 250 mg kg
À1 d.w.
Other plastic additives, such as the monomer bisphenol A, have also been
screened for in vivo toxicity in the epigeic species E. fetida and D. veneta, and
life-history traits and the immune system (measured as coelomocyte viability) were
the targeted endpoints using chronic artificial soil and acute contact test exposures
[58]. Although some species-related differences in sensitivity were seen, the immune
system was not affected, while the reproductive outcome was compromised. The
same researchers [59] selected E. fetida as bioindicator to search further into
molecular gene expression effects due to BPA exposures in biomarkers related to
endocrine function (EcR, MAPR, AdipoR), epigenetic mechanisms (DNMTs),
genotoxicity (PARP1), stress responses (HSC70 4) and metabolism
(metallothionein). Although soil exposure tests did not reveal effects at the molecular level in whole tissue homogenates, the particular analysis of the male organs
showed effects on the endocrine-related genes, epigenetic mechanisms (DNMT1 and
DNMT3b), the genotoxic-related PARP1 and the stress-related Hsc70 4 genes. The
contact test for acute exposures also indicated effects on detoxification and stress
pathways in whole tissue homogenates such as HSC70 4 and metallothionein,
epigenetic mechanisms (Piwi2) and genotoxicity (PARP1) in addition to disruptive
effects on male organs.
Flame retardants are also plastic additives of environmental concern in contaminated soils. The flame retardant tetrabromobisphenol A (TBBPA) is frequently
present in plastics and electronic equipment and displays endocrine-disrupting
properties [60]. TBBPA alone and under co-exposure with a toxic metal (Cd) are
present in e-waste-contaminated soils. The consequences of single and combined
exposures were evaluated in earthworms using several biomarker endpoints together
with histological damage examination. The species were the standard model
E. fetida and the soil-inhabiting and more ecologically relevant anecic Metaphire
guillelmi. All biomarkers considered confirmed a higher sensibility in the naturalBiomarkers in Earthworms
329
damage over time and dose [54]. Another particular phthalate, di-(2-ethylhexyl)
phthalate (DEHP), was spiked in natural soil (1, 3, 9 and 27 mg kg
À1 ), and several
biomarkers were evaluated in E. fetida coelomocytes. Some parameters increased,
SOD, LPO, MT, HSP70 and genotoxicity (comet assay), while others decreased:
POD, LMS (NRR) and mitochondrial membrane potential difference in relation to
concentration and over time [55]. The authors proposed a precautionary level of
3 mg kg
À1 for potential risk of phthalates in soils (based on DEHP results).
Assessment of toxicity due to polyethylene (PE) pellet (250–1,000 μm) exposure
in E. andrei was conducted at a wide range of PE concentrations (max 1 mg kg
À1 ) in
soil for 28 days [56]. Damage in gut tissue was revealed at all concentrations in a
dose-dependent manner as well as toxicity of the immune system. More recently, the
same authors evaluated low-density polyethylene microplastics (MP) toxicity in the
same model species, following the same standardised protocol but considering
additional oxidative stress parameters (GST and LPO) as well as the anaerobic
metabolism marker (LDH) as endpoints [57]. The authors concluded that MP
exposure caused oxidative stress and changes in energy metabolism more significantly after soil exposures over 250 mg kg
À1 d.w.
Other plastic additives, such as the monomer bisphenol A, have also been
screened for in vivo toxicity in the epigeic species E. fetida and D. veneta, and
life-history traits and the immune system (measured as coelomocyte viability) were
the targeted endpoints using chronic artificial soil and acute contact test exposures
[58]. Although some species-related differences in sensitivity were seen, the immune
system was not affected, while the reproductive outcome was compromised. The
same researchers [59] selected E. fetida as bioindicator to search further into
molecular gene expression effects due to BPA exposures in biomarkers related to
endocrine function (EcR, MAPR, AdipoR), epigenetic mechanisms (DNMTs),
genotoxicity (PARP1), stress responses (HSC70 4) and metabolism
(metallothionein). Although soil exposure tests did not reveal effects at the molecular level in whole tissue homogenates, the particular analysis of the male organs
showed effects on the endocrine-related genes, epigenetic mechanisms (DNMT1 and
DNMT3b), the genotoxic-related PARP1 and the stress-related Hsc70 4 genes. The
contact test for acute exposures also indicated effects on detoxification and stress
pathways in whole tissue homogenates such as HSC70 4 and metallothionein,
epigenetic mechanisms (Piwi2) and genotoxicity (PARP1) in addition to disruptive
effects on male organs.
Flame retardants are also plastic additives of environmental concern in contaminated soils. The flame retardant tetrabromobisphenol A (TBBPA) is frequently
present in plastics and electronic equipment and displays endocrine-disrupting
properties [60]. TBBPA alone and under co-exposure with a toxic metal (Cd) are
present in e-waste-contaminated soils. The consequences of single and combined
exposures were evaluated in earthworms using several biomarker endpoints together
with histological damage examination. The species were the standard model
E. fetida and the soil-inhabiting and more ecologically relevant anecic Metaphire
guillelmi. All biomarkers considered confirmed a higher sensibility in the naturalBiomarkers in Earthworms
329