You are here:
Life-stage dependent response in zebrafish (Danio rerio) to phototoxicity of TiO2 nanoparticles
Citation:
Ma, H. AND S. Diamond. Life-stage dependent response in zebrafish (Danio rerio) to phototoxicity of TiO2 nanoparticles. Presented at Society for Environmental Toxicology and Chemistry, November 11 - 15, 2012.
Impact/Purpose:
not applicable
Description:
The Zebrafish, and especially its embryo stage, has been increasingly used as a model to evaluate toxicity of manufactured nanomaterials. However, many studies have indicated that the chorion may protect developing embroys from the toxic effects of nanomaterials, suggesting that post-hatch life-stages may be more susceptible to nanomaterial toxicity and should continue to be tested to fully discern the potential hazard and risk of nanomaterials. The current study aimed to identify the “window of susceptibility” (the life stage that is most sensitive to toxicity) of zebrafish to phototoxicity of TiO2 nanoparticles. To this end, 96-h toxicity tests were conducted to zebrafish at different life-stage (embryo [< 2-h post fertilization, “yolk-sac” larvae [< 48-h post hatch], “free-swimming” larvae [21-d post hatch], and juvenile [50-d post hatch]) by exposing test organisms to TiO2 nanoparticles under simulated solar radiation (4 h within every 24 h during the 96-h exposure period). Toxicity endpoints included hatching rate, % malformation, and % mortality for embryonic test, and mortality only for all other tests. For zebrafish embryo, TiO2 concentration at 1-20 mg/l caused no mortality, had no impact on 72-h hatching rate, but induced malformation in fish embryo/larvae by up to 20%. TiO2 at higher concentration (up to 200 mg/l) caused mortality to fish embryo/larvae with a 96-h LC50 of 34.4 mg/l (95% CI: 24.5, 48.4), but had no impact on hatching rate, suggesting that mortality mainly occurred after hatching. The “yolk-sac” larvae had a 96-h LC50 of 20.3 mg/l (95% CI: 18.9-21.8) and the “free-swimming” larvae had a 96-h LC50 of 134.6 mg/l (95% CI: 103.7, 174.7). For juvenile fish, TiO2 concentration up to 200 mg/l caused mortality less than 25% after 96-h exposure. The finding that newly hatched zebrafish larvae (i.e., < 48-h post hatch) are more sensitive than fish embryo in response to TiO2 phototo