Mice received oral yttrium oxide, calcium hydroxide or calcium titanate nanoparticles, alone or together, at 50 mg/kg body weight three times a week for two weeks, and liver tissue was examined. Yttrium oxide alone did not change DNA integrity or reactive oxygen species compared with controls, and the combined dose showed less damage than calcium hydroxide alone.
Key numbers
- Acute screen: no signs of toxicity over 14 days after single oral 2000 mg/kg doses; LD50 taken as above 2000 mg/kg (Results, p. 3).
- Test dose 50 mg/kg body weight, three times a week for two weeks (Methods, p. 2).
- Comet assay in liver, mean +/- SD (n = 5): control tail length 6.13 +/- 1.38 px, %DNA in tail 27.44 +/- 8.41, tail moment 2.08 +/- 1.07; yttrium oxide 6.05 +/- 1.68 px, 23.29 +/- 4.44%, 1.73 +/- 0.88 (Table 2, p. 3).
- HSP-70 gene expression was significantly raised after yttrium oxide alone compared with the calcium hydroxide group (Results, p. 4).
Methods (brief)
Commercial nanopowders (under 100 nm) were suspended in water and given by gavage. Liver tissue was analyzed by alkaline comet assay, DCFH-DA staining for reactive oxygen species and qRT-PCR for p53, Kras and HSP-70.
Evidence fitness
Supports a limited statement that repeated oral yttrium oxide nanoparticles at 50 mg/kg did not cause detectable liver DNA damage in mice. It does not support dietary exposure, occurrence or human health conclusions, and the recommendation to co-administer yttrium oxide is the authors’ interpretation.
Limitations
Five mice per group, one dose and no tissue yttrium measurement. Particle characterization is referenced to the group’s earlier studies. A companion paper on brain tissue uses an identical design and may share animals.
Related evidence
Update history
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