In ovo nanoinjection of triclosan, diclofenac and carbamazepine affects embryonic development of medaka fish (Oryzias latipes)

We examined the toxicity of three pharmaceuticals and personal care products (PPCPs) - triclosan (TCS), diclofenac (DCF), and carbamazepine (CBMZ) - on embryonic development of Japanese medaka (Oryzias latipes) using in ovo nanoinjection. Medaka eggs (8 h post-fertilization; late blastula stage) were injected with 0.5 nL of triolein (vehicle control) or 0.5 nL of PPCPs, using different doses of TCS (1, 5, or 9 ng), DCF (1, 5, or 12 ng), or CBMZ (1, 5, or 12 ng) per egg in triolein, in addition to uninjected control. Following injection, we recorded survival, embryonic lesions, delay in embryonic development (eye, embryonic body and internal organs), heart beat rate, hatchability, and hatching time of embryos and upward swimming of larvae. As a result, injected PPCPs caused toxic responses to medaka embryos during embryonic development and around the day of hatching. Based on estimated EC₅₀ values of PPCPs doses on survival of injected embryos at hatching, TCS (at a dose of 4.2 ng egg^-1) was generally more toxic to medaka embryos, followed by DCF (6.0 ng egg^-1), and CBMZ (13.1 ng egg^-1). We conclude that the nanoinjection medaka embryos model is a valuable tool for analyzing the effects of chemicals on the development of fish embryos and feasibility of nanoinjecting PPCPs into small fish eggs perhaps mimicking early exposure resulting from oocyte uptake of contaminants from maternal extra gonadal tissues.