title: Sewage sludge toxicity assessment using earthworm Eisenia fetida: can biochemical and histopathological analysis provide fast and accurate insight?
abstract: Sewage sludge (SS) is a complex organic by-product of wastewater treatment plants. Deposition of large amounts of SS can increase the risk of soil contamination. Therefore, there is an increasing need for fast and accurate assessment of SS toxic potential. Toxic effects of SS were tested on earthworm Eisenia fetida tissue, at the subcellular and biochemical level. Earthworms were exposed to depot sludge (DS) concentration ratio of 30 or 70 %, to undiluted and to 100 and 10 times diluted active sludge (AS). The exposure to DS lasted for 24/48 h (acute exposure), 96 h (semi-acute exposure) and 7/14/28 days (sub-chronic exposure) and 48 h for AS. Toxic effects were tested by the measurements of multixenobiotic resistance mechanism (MXR) activity and lipid peroxidation levels, as well as the observation of morphological alterations and behavioural changes. Biochemical markers confirmed the presence of MXR inhibitors in the tested AS and DS and highlighted the presence of SS-induced oxidative stress. The MXR inhibition and thiobarbituric acid reactive substance (TBARS) concentration in the whole earthworm's body were higher after the exposition to lower concentration of the DS. Furthermore, histopathological changes revealed damage to earthworm body wall tissue layers as well as to the epithelial and chloragogen cells in the typhlosole region. These changes were proportional to SS concentration in tested soils and to exposure duration. Obtained results may contribute to the understanding of SS-induced toxic effects on terrestrial invertebrates exposed through soil contact and to identify defence mechanisms of earthworms.
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: S
authors.initials: S
authors.lastname: Babić
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: J
authors.initials: J
authors.lastname: Barišić
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: O
authors.initials: O
authors.lastname: Malev
authors.affiliation: Division of Zoology, Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia.
authors.forename: G
authors.initials: G
authors.lastname: Klobučar
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: N Topić
authors.initials: NT
authors.lastname: Popović
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: I
authors.initials: I
authors.lastname: Strunjak-Perović
authors.affiliation: Division for Marine and Environmental Research, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: N
authors.initials: N
authors.lastname: Krasnići
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia.
authors.forename: R
authors.initials: R
authors.lastname: Čož-Rakovac
authors.affiliation: Division of Materials Chemistry, Ruđer Bošković Institute, Zagreb, Croatia. rsauer@pathcon.com.|PathCon Laboratories EU, Prilaz Ivana Visina 1-3, 10000, Zagreb, Croatia. rsauer@pathcon.com.
authors.forename: R Sauerborn
authors.initials: RS
authors.lastname: Klobučar
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004784:Environmental Monitoring / Q000379:methods*; D015227:Lipid Peroxidation / Q000187:drug effects; D009835:Oligochaeta / Q000187:drug effects* / Q000378:metabolism; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000633:toxicity*; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D012722:Sewage; D012987:Soil; D012989:Soil Pollutants; D017392:Thiobarbituric Acid Reactive Substances; D014874:Water Pollutants, Chemical
keywords: Earthworm; Histopathology; Lipid peroxidation; MXR; Oxidative stress; Soil toxicity