Multigeneration reproductive effects of three phthalate esters in Japanese medaka (Oryzias latipes)

Japanese medaka (Oryzias latipes), a freshwater teleost, was used to examine multigeneration reproductive effects of di-n-butyl (DBP), diisononyl (DINP), and diisodecyl (DIDP) phthalate. In the F0 generation DINP and DIDP were fed to juvenile medaka at 20 μ/g of feed, at 5% fish body weight per day. In a separate study DBP was fed at 12.2, 65 and 776 μg/kg/day. Exposure continued through sexual maturation. Collected eggs were hatched for the F1 and subsequently the F2 generations. The endpoints included survival, embryonal development, growth, histopathologic changes, gonadal-somatic index, sexual development, fecundity, vitellogenin (VG) induction and microsomal testosterone metabolism. Neither DINP nor DIDP caused reproductive toxicity based on the endpoints evaluated. However, DBP at 776 μg/kg/day induced vitellogenin, and ovo-testes production in F1 generation male fish and significantly reduced egg production, when compared to the ethanol control. Multigeneration studies can provide important information on low-dose exposure of fish to persistent pollutants at environmentally relevant concentrations. Studies of this type are needed to fully evaluate the relationship between environmental endocrine biomarkers (e.g. VG) and alteration of reproduction (ES-22330, ES-29782, NJAES-01126).