dwelling species under co-exposures with respect to E. fetida [61]. Radiolabelled
14 C-TBBPA was used to spike soil and follow up metabolism, biomarker responses
and metabolite identification in M. guillelmi [62] that will be further addressed in the
next section. Exposures to other brominated flame retardants such as the more
persistent decabromodiphenyl ether congener (BDE209) and the metal Pb, in single
and combined mixtures, as common chemicals found in e-waste recycling sites, were
evaluated in E. fetida in a soil test. In this case, a behaviour endpoint (avoidance test
after 48 h) and the measure of DNA damage in coelomocytes (after 28 days) were the
biomarkers selected [63]. A follow-up of these e-waste components was carried out
in a soil test that considered three repeated exposures to these two contaminants for
10 days. After this preparation period, biomarker measures were related to antioxidant responses and gene expression at times: 2, 7, 14 and 28 days [64]. Antioxidant
responses and gene expression were correlated to the exposures, and SOD activity
seemed to be more sensitive than CAT activity measures. Gene expression of genes
related to antioxidant defences (SOD and CAT) and HSP70 was studied after
exposures at several concentrations (1–400 mg kg
À1 ) of the brominated chemicals:
TBBPA, hexabromocyclododecane (HBCD) and BDE 209 [65]. Gene upregulation
was chemical- and concentration-dependent suggesting the toxicity order
TBBPA>HBCD>BDE209 and the HSP70 gene expression being the most sensitive
biomarker. A particular BDE 47-associated toxicity in soil-exposed E. fetida was
considered after 14-day exposures at a wide range of concentrations (10–400 mg kg
À1 ) and gene expression evaluated [66]. Out of the four genes considered,
SOD upregulation and Hsp70 downregulation stand out as well as growth rate
inhibition as the parameters more consistently affected. In addition to more traditional biomarkers, a metabolomics consideration was incorporated into some of the
former studies evaluating exposure in E. fetida to relevant flame retardants under
similar experimental dose and time conditions. That is, BDE 47 and BDE 209 altered
metabolites involved in energy metabolism, Krebs cycle, amino acid metabolism,
nerve activities and osmotic/compatible solute balance [67]. However, HBCD
exposure induced oxidative stress (SOD and GST gene expression) and impaired
metabolic homeostasis including anaerobic metabolism as indicated by seven metabolite modifications in those exposed [68]. All former metabolomics approaches
confirmed the sensitive nature of the NMR techniques in relation to ecotoxicological
assessment of flame retardants.
Other organohalogenated chemicals of environmental concern are
polyfluoroalkyl substances with perfluorooctane sulfonic acid (PFOS) as the main
metabolite detected in environmental matrices and being N-ethyl perfluorooctane
sulfonamidoethanol (EtFOSE) its main precursor. A recent study by Zhao et al. [69]
evaluated the degradation of EtFOSE (0.9 nmol g
À1 d.w.) over a 10-day period in a
quartz sand experiment and measured the responses in E. fetida in biomarkers
encompassing oxidative stress and damage. In addition to metabolite identification,
a time trend activation of POD, SOD, CAT and GST enzymatic activities and
damage revealed as DNA (8-OH dG) and ROS formation was evidenced at the
longest exposures. As substitute alternative of more toxic halogenated flame retardant, organophosphorus flame retardants also require investigation. Triphenyl
330
M. Solé
14 C-TBBPA was used to spike soil and follow up metabolism, biomarker responses
and metabolite identification in M. guillelmi [62] that will be further addressed in the
next section. Exposures to other brominated flame retardants such as the more
persistent decabromodiphenyl ether congener (BDE209) and the metal Pb, in single
and combined mixtures, as common chemicals found in e-waste recycling sites, were
evaluated in E. fetida in a soil test. In this case, a behaviour endpoint (avoidance test
after 48 h) and the measure of DNA damage in coelomocytes (after 28 days) were the
biomarkers selected [63]. A follow-up of these e-waste components was carried out
in a soil test that considered three repeated exposures to these two contaminants for
10 days. After this preparation period, biomarker measures were related to antioxidant responses and gene expression at times: 2, 7, 14 and 28 days [64]. Antioxidant
responses and gene expression were correlated to the exposures, and SOD activity
seemed to be more sensitive than CAT activity measures. Gene expression of genes
related to antioxidant defences (SOD and CAT) and HSP70 was studied after
exposures at several concentrations (1–400 mg kg
À1 ) of the brominated chemicals:
TBBPA, hexabromocyclododecane (HBCD) and BDE 209 [65]. Gene upregulation
was chemical- and concentration-dependent suggesting the toxicity order
TBBPA>HBCD>BDE209 and the HSP70 gene expression being the most sensitive
biomarker. A particular BDE 47-associated toxicity in soil-exposed E. fetida was
considered after 14-day exposures at a wide range of concentrations (10–400 mg kg
À1 ) and gene expression evaluated [66]. Out of the four genes considered,
SOD upregulation and Hsp70 downregulation stand out as well as growth rate
inhibition as the parameters more consistently affected. In addition to more traditional biomarkers, a metabolomics consideration was incorporated into some of the
former studies evaluating exposure in E. fetida to relevant flame retardants under
similar experimental dose and time conditions. That is, BDE 47 and BDE 209 altered
metabolites involved in energy metabolism, Krebs cycle, amino acid metabolism,
nerve activities and osmotic/compatible solute balance [67]. However, HBCD
exposure induced oxidative stress (SOD and GST gene expression) and impaired
metabolic homeostasis including anaerobic metabolism as indicated by seven metabolite modifications in those exposed [68]. All former metabolomics approaches
confirmed the sensitive nature of the NMR techniques in relation to ecotoxicological
assessment of flame retardants.
Other organohalogenated chemicals of environmental concern are
polyfluoroalkyl substances with perfluorooctane sulfonic acid (PFOS) as the main
metabolite detected in environmental matrices and being N-ethyl perfluorooctane
sulfonamidoethanol (EtFOSE) its main precursor. A recent study by Zhao et al. [69]
evaluated the degradation of EtFOSE (0.9 nmol g
À1 d.w.) over a 10-day period in a
quartz sand experiment and measured the responses in E. fetida in biomarkers
encompassing oxidative stress and damage. In addition to metabolite identification,
a time trend activation of POD, SOD, CAT and GST enzymatic activities and
damage revealed as DNA (8-OH dG) and ROS formation was evidenced at the
longest exposures. As substitute alternative of more toxic halogenated flame retardant, organophosphorus flame retardants also require investigation. Triphenyl
330
M. Solé