Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC50) of nano-Zn and nano-ZnO were estimated to be near 50 mg/L for radish, and about 20 mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles. Engineered nanoparticles can inhibit the seed germination and root growth.

Plant uptake is a major pathway by which toxic metals can enter the food chain. In this laboratory study we grew spinach, radish, and perennial ryegrass on sand blends containing 50% waste foundry sand (WFS) to assess the availability of Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, V, and Zn. The WFSs utilized in this study were from aluminum, iron, and steel foundries. Although there were differences in the amounts of metals accumulated by the various plant species, excessive amounts of heavy metals were not taken up, regardless of WFS treatment. In spinach and radish, B, Cu, Fe, Mn and Zn were found to be within or close to the sufficiency range for agronomic crops. In ryegrass cuttings at 27, 57, and 87 days, Cu and Zn were within sufficiency ranges, but plants were Fe deficient and contained elevated concentrations of B, Mn, and Mo. Data from this study will be useful for state regulatory agencies interested in developing beneficial use regulations for WFSs.