Diana M. Papoulias Stephanie D. Pastva Alan L. Blankenship John C. Meadows Donald E. Tillitt John P. Giesy Sergio A. Villalobos 2003 <p>The toxicity of <i>o,p′</i>-DDE (1,1-dichloro-2-(<i>p</i>-chlorophenyl)-2-(<i>o</i>-chlorophenyl) ethylene) was evaluated in embryos of medaka (<i>Oryzias latipes</i>) 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 <i>o,p′</i><span>-DDE</span> 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, <i>o,p′</i><span>-DDE</span> 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 <i>o,p′</i><span>-DDE</span>/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.</p> application/pdf 10.1016/S0045-6535(03)00583-6 en Elsevier Toxicity of <i>o,p′</i>-DDE to medaka d-rR strain after a one-time embryonic exposure by in ovo nanoinjection: An early through juvenile life cycle assessment article