title: Acute toxicity of 353-nonylphenol and its metabolites for zebrafish embryos.
abstract: OBJECTIVE
  Nonylphenol (NP) can be detected in the aquatic environment all over the world. It is applied as a technical mixture of isomers of which 353-NP is the most relevant both in terms of abundance (about 20% of total mass) and endocrine potential. 353-NP is metabolised in sewage sludge. The aims of the present study were to determine and to compare the acute toxicity of t-NP, 353-NP and its metabolites as well as to discuss if the toxicity of 353-NP changes during degradation.
  
  
  METHODS
  353-NP and two of its metabolites were synthesised. The zebrafish embryo test was performed according to standard protocols. Several lethal and non-lethal endpoints during embryonal development were reported. NOEL, LOEL and EC50 were calculated.
  
  
  RESULTS
  All tested compounds caused lethal as well as non-lethal malformations during embryo development. 353-NP showed a higher toxicity (EC50 for lethal endpoints 6.7 mg/L) compared to its metabolites 4-(3.5-dimethyl-3-heptyl)-2-nitrophenol (EC50 13.3 mg/L) and 4-(3,5-dimethyl-3-heptyl)-2-bromophenol (EC50 27.1 mg/L).
  
  
  CONCLUSIONS
  In surface water, concentrations of NP are far below the NOEC identified by the zebrafish embryo test. However, in soils and sewage sludge, concentrations may reach or even exceed these concentrations. Therefore, sludge-treated sites close to surface waters should be analysed for NP and its metabolites in order to detect an unduly high contamination due to runoff events.
  
  
  CONCLUSIONS
  The results of the present study point out that the toxicity of 353-NP probably declines during metabolisation in water, sediment and soil, but does not vanish since the major metabolites exhibit a clear toxic potential for zebrafish embryos.
  
  
  CONCLUSIONS
  Metabolites of environmental pollutants should be included in the ecotoxicological test strategy for a proper risk assessment.
authors.affiliation: Johann Heinrich von Thünen-Institute (vTI), Federal Research Institute for Rural Areas, Forests and Fisheries, Institute for Fishery Ecology, Palmaille 9, 22767, Hamburg, Germany. ulrike.kammann@vti.bund.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kammann
authors.forename: Michael
authors.initials: M
authors.lastname: Vobach
authors.forename: Werner
authors.initials: W
authors.lastname: Wosniok
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäffer
authors.forename: Andreas
authors.initials: A
authors.lastname: Telscher
mesh_terms: D000818:Animals; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D012722:Sewage / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology*
chemical_list: D010636:Phenols; D012722:Sewage; D014874:Water Pollutants, Chemical; C025256:nonylphenol