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. The authors report that yttrium oxide alone caused no remarkable DNA damage, oxidative stress or inflammation gene changes in brain tissue and that co-administration lessened the damage from the calcium nanoparticles.
Key numbers
- Acute screen: single oral 2000 mg/kg doses caused no signs of toxicity over 14 days, so LD50 was taken as above 2000 mg/kg (Results, p. 4).
- Test dose 50 mg/kg body weight, three times a week for two weeks; yttrium oxide particles under 50 nm, at least 99.9% trace-metal purity (Methods).
- Comet assay in brain, mean +/- SD (n = 5): control tail length 4.14 +/- 1.12 px, %DNA in tail 18.15 +/- 4.74, tail moment 0.93 +/- 0.47; yttrium oxide 5.69 +/- 0.13 px, 32.72 +/- 7.44%, 1.83 +/- 0.68 (Table 2, p. 5).
- In Table 2 the %DNA in tail for yttrium oxide carries a different significance letter from the control, although the text describes no remarkable change (Table 2, p. 5).
Methods (brief)
Commercial nanopowders were suspended in water and given by gavage. Brain tissue was analyzed by alkaline comet assay, fluorescent detection of reactive oxygen species, rhodamine staining for mitochondrial membrane potential and qRT-PCR for presenilin-1, TNF-alpha and IL-6.
Evidence fitness
Supports a limited statement that repeated oral yttrium oxide nanoparticles at 50 mg/kg did not markedly change most brain genotoxicity markers in mice. It uses one dose, one particle type and small groups, and does not support dietary exposure, occurrence or human health conclusions.
Limitations
Five mice per group, one dose level and no measurement of yttrium in tissues. The tail-DNA result for yttrium oxide alone appears statistically different from control in the table, which the narrative does not address. The same research group reported liver results from an identically designed experiment, so the two papers may share animals.
Related evidence
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