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Germination and early plant development of 10 plant species exposed to Nano TiO2 and CeO2
Citation:
Andersen, C., Milt Plocher, M. Storm, G. King, AND P. Rygiewicz. Germination and early plant development of 10 plant species exposed to Nano TiO2 and CeO2. Presented at SETAC North America 34th Annual Meeting, Nashville, TN, November 17 - 21, 2013.
Impact/Purpose:
Nanoparticles have been incorporated into numerous consumer products and are likely to reach the terrestrial environment in significant concentrations, yet little is known about their potential toxicity to terrestrial organisms. Standard testing protocols for testing the toxicity of new materials are based on those developed for chemicals in solution, and may not be appropriate for assessing the toxicity of nanoparticles. To examine the effects of TiO2 and CeO2 on terrestrial plants, 10 agronomic plant species were exposed to different concentrations of each nano particle (0, 250, 500 and 1000 ug/l) and followed to examine effects on germination and early seedling development. For TiO2, cabbage showed increased and corn decreased percent germination, while the other 8 species showed no significant change in percent germination. However, TiO2 accelerated the timing of germination in 5 species, and had significant effects on final root length in 9 of 10 species, with five species showing increased and four species showing decreased root length. For CeO2, only one species showed a change (slight decrease) in germination percent, while 5 species showed a decrease in final root length. Overall, the responses observed did not consistently relate to nanoparticle concentration, suggesting that concentration may not be an appropriate metric for expressing effects with these two nanoparticles. The results suggest that TiO2 and CeO2 have different effects on early plant growth of agronomic species, which may alter the timing of specific developmental events during their life cycle. In addition, the standard germination test, which is commonly used for toxicity screening of new materials, may not detect the subtle but potentially more important changes associated with early growth and development in terrestrial plants. (Contact: Chris Andersen, x4791)
Description:
Ten agronomic plant species were exposed to different concentrations of nano-TiO2 or CeO2 (0, 250, 500 and 1000 ug/l) and followed to examine effects on germination and early seedling development. For TiO2, cabbage showed increased and corn decreased percent germination, while the other 8 species showed no significant change in percent germination. However, TiO2 accelerated the timing of germination in 5 species, and had significant effects on final root length in 9 of 10 species, with five species showing increased and four species showing decreased root length. For CeO2, only one species showed a change (slight decrease) in germination percent, while 5 species showed a decrease in final root length. In a companion study with Arabidopsis, CeO2 was found to alter gene expression more strongly in roots than shoots, consistent with the hypothesis that TiO2 and CeO2 may affect roots and shoots differently. Overall, the responses observed did not consistently relate to nanoparticle concentration, suggesting that concentration may not be an appropriate metric for expressing effects with these two nanoparticles. The results suggest that TiO2 and CeO2 have different effects on early plant growth of agronomic species, which may alter the timing of specific developmental events during their life cycle. In addition, the standard germination test, which is commonly used for toxicity screening of new materials, may not detect the subtle but potentially more important changes associated with early growth and development in terrestrial plants.