Comparative uptake and impact of TiO₂ nanoparticles in wheat and rapeseed

Up to 2 million tons per year of titanium dioxide (TiO₂) nanoparticles (NP) are produced worldwide. This extensive production is postulated to result in release into the environment with subsequent contamination of soils and plants; however, few studies have examined TiO₂-NP uptake and impact on plants. In this study, wheat and rapeseed plantlets were exposed to 14 nm or 25 nm anatase TiO₂-NP in hydroponics conditions, either through root or leaf exposure. Microparticle-induced x-ray emission (μPIXE) coupled with Rutherford backscattering spectroscopy (RBS) was used to quantify absorbed titanium (Ti). Micro x-ray fluorescence (μXRF) based on synchrotron radiation was used to evaluate Ti distribution in roots and leaves. Our results show that both TiO₂-NP are accumulated in these plantlets upon root exposure and that Ti content is higher in rapeseed than wheat. Ti distribution in root cross sections depended on NP agglomeration state. NP are also accumulated in plantlets upon leaf exposure. Finally, it was found that TiO₂-NP exposure induced increased root elongation but did not affect germination, evapotranspiration, and plant biomass. Taken together, these results confirm that TiO₂-NP may be accumulated in plant crops but may only moderately impact plant development.