title: Toxicity of o,p'-DDE to medaka d-rR strain after a one-time embryonic exposure by in ovo nanoinjection: an early through juvenile life cycle assessment.
abstract: The toxicity of o,p'-DDE (1,1-dichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethylene) was evaluated in embryos of medaka (Oryzias latipes) following a one time exposure via nanoinjection. Medaka eggs (early gastrula) were injected with 0.5 nl of triolein (vehicle control) or 0.5 nl of 4 graded doses (0.0005-0.5 ng/egg) of o,p'-DDE in triolein. Embryos were allowed to develop, and fry were reared. Embryonic survival was monitored daily during the first 10 d until hatching and thereafter, on a weekly basis until day 59, at which time the fish were monitored for sexual maturity until day 107. In general, o,p'-DDE caused a dose- and time-dependent mortality. No changes in mortality were observed between the last two time points (day 38 and 59, respectively), and hence a 59 day-LD50 of 346 ng o,p'-DDE/egg was derived from the linear dose-response relationship. Prior to late stage death, only isolated cases of cardiovascular lesions and spinal deformities were observed, but were not dose-dependent. The lowest observable adverse effect level (LOAEL), based on upper 95% CI for regression line=0.0018 mg/kg, and the LOAEL based on exposure doses=0.5 mg/kg. Likewise, the no observable adverse effect level (NOAEL) based on linear extrapolation to 100% survival=0.0000388 mg/kg, while the NOAEL based on exposure doses=0.05 mg/kg. The nanoinjection medaka model has potential in the study of hormonally active compounds in the environment.
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian; D007928:Lethal Dose 50; D008018:Life Cycle Stages / Q000187:drug effects*; D008845:Microinjections; D008939:Mitotane / Q000031:analogs & derivatives* / Q000633:toxicity*; D019055:No-Observed-Adverse-Effect Level; D009990:Oryzias / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism*; D010063:Ovum / Q000187:drug effects / Q000473:pathology; D023382:Toxicity Tests, Acute
chemical_list: D008939:Mitotane; C054919:2,2-(2-chlorophenyl-4'-chlorophenyl)-1,1-dichloroethene