High Doses of Intravenously Administered Titanium Dioxide Nanoparticles Accumulate in the Kidneys of Rainbow Trout but with no Observable Impairment of Renal Function

Abstract

Our recent work suggests limited uptake of unstabilized metal oxide nanoparticles via water into fish, however, some other studies have indicated such exposures can induce oxidative stress. To investigate tissue distribution and toxicity of titanium dioxide (TiO(2)) nanoparticles that may enter into fish, we conducted a series of injection studies. Rainbow trout (Oncorhynchus mykiss) were intravenously injected with 100 microg TiO(2) nanoparticles and the content of titanium in blood, brain, gills, liver, and kidney quantified at time points between 6 h and 90 days using inductively coupled plasma optical emission spectroscopy. Injected Ti was concentrated in the kidneys and remained there up to 21 days, however, there was evidence of clearance of TiO(2) at 90 days. Ti accumulation in the liver was 15 times lower than in the kidney with no apparent clearance. Using TEM we showed nanoparticles were localized in tissue vesicles surrounding the kidney tubules. In a second injection study, rainbow trout were injected with 100 microg TiO(2) and plasma samples from individual fish analyzed for total protein and creatinine content at time points between 6 h and 21 days to assess for possible effects on kidney function. No effect of TiO(2) on total plasma protein content or creatinine concentrations were found indicating that neither urine production nor glomerular filtration rate were affected. We conclude that in trout upon a single high dose exposure of TiO(2) nanoparticles via the bloodstream, TiO(2) accumulates in the kidneys but has minimal effect on kidney function.

The mechanism of oxidative damage in the nephrotoxicity of mice caused by nano-anatase TiO2

“…Wang et al [17] showed that there was no significant difference in the renal coefficients between experimental groups and the control, but the renal dysfunction was found in the treated mice because of the high serum BUN and Cr levels and observed the serious pathological changes of kidneys of female mice following the 2-week exposure to the 5 g/kg BW 80 nm and fine TiO 2 particles. However, Scown et al [23] showed that even high doses of intravenously injected TiO 2 nanoparticles (34.2 nm, a mixture of rutile and anatase) caused very limited overt impairment of the renal function or oxidative stress in the blood in rainbow trout. Our current study indicates that the mouse nephrotoxicity is characteristic of the increased Cr level, the decreased BUN, UA level and pathological changes of kidneys.…”

“…The enhancement of lipids peroxide in the mouse liver caused by nano-anatase TiO 2 (5 nm) likely implicated an oxidative attack that was activated by a reduction of antioxidative defence mechanism [17]. Scown et al [23] reported that in rainbow trout, upon a single high-dose exposure of TiO 2 nanoparticles (34.2 nm, a mixture of rutile and anatase) via the bloodstream, TiO 2 was accumulated in the kidneys but had minimal effect on kidney functions.…”

Interspecies comparisons on the uptake and toxicity of silver and cerium dioxide nanoparticles

“…Tissues were degraded in 4 ml 70% HNO 3 and 1 ml 30% H 2 O 2 . Liquid was removed by evaporation, and the residues were resuspended in 10 ml 10% HNO 3 [22].…”

Aquatic toxicity of manufactured nanomaterials: challenges and recommendations for future toxicity testing

“…[145] This hypothesis has since been given further credence by the observation that injection of TiO 2 NMs into caudal vasculature, an approach that avoids the issue of bioavailability, resulted in no significant effects in internal tissues, including the kidney, the principle site of accumulation. [146,147] In spite of their apparent low bioavailability, the interaction of TiO 2 NMs at external epithelia may have resulted in important ecological effects. For example, Ramsden et al [148] report decreased fecundity in zebrafish exposed to TiO 2 NMs, even though the accumulation of the NM was not observed.…”