Study of nanocoated material did not show translocation to remote organs

Just published! A German study by Fraunhofer of toxicity of nanoparticles with the same core but different chemical surface modifications. Conclusions are:
"This study compared the toxic effects of a triple of TiO2 nanoparticles after a 28-day nose-only inhalation. Three TiO2 varieties used for this study did not show pronounced differences in the exhibited toxicity. Thus, the variation in properties regarding crystal structure and surface modification did not alter considerably the interactions with biological structures in the respiratory tract. This was not expected as surface modifications sometimes are reported to trigger a dramatically increased toxic potential as compared to uncoated core particles. Translocation to remote organs was negligible and values higher than the detection of limits observed in some few animals. This confirms for the poorly soluble TiO2 particles no considerable translocation to liver and no translocation at all to brain."


Full study report

Remarkeble! But how far can we extrapolate? Is the effect of the chemical surface limited?