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Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles
Citation:
Andersen, C., G. King, Milt Plocher, M. Storm, L. Pokhrel, Mark G Johnson, AND P. Rygiewicz. Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 35(9):2223-2229, (2016).
Impact/Purpose:
Engineered nanoparticles (ENMs) have been recognized as valuable components of new technologies and are currently being used in a variety of consumer products due to their unique physical, chemical, and electrical properties. The properties that make these particles functionally unique also may influence their toxicity to ecological organisms. Developing screening tools to evaluate the environmental health and safety of engineered nanomaterials represents a significant challenge for regulators because of the unique properties that emerge at the nanoscale. Unlike soluble chemicals, ENM exposure occurs via colloidal suspensions of insoluble particles rather than as true solutions, and as a result, particle suspensions often behave in a manner that may not be addressed in existing ecological testing protocols. One step in assessing the environmental health and safety of new materials is to evaluate existing approaches to determine the degree to which they are appropriate for testing ENMs or whether they can be modified to accommodate ENMs. WED scientists examined ten agronomic plant species exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) to examine potential effects on germination and early seedling development. We modified a standard test protocol developed for soluble chemicals (OPPTS 850.4200) to determine if such an approach might be useful for screening engineered nanomaterials. Eight of 10 species responded to nTiO2, and 5 species responded to nCeO2. Overall, it appeared that early root growth was a more sensitive indicator of potential effects from ENM exposure than germination. The observed effects did not always relate to the exposure concentration, indicating that mass-based concentration may not fully explain developmental effects of these two ENMs. The results suggest that nTiO2 and nCeO2 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, standard plant germination tests, which are 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.
Description:
Ten agronomic plant species were exposed to different concentrations of nano titanium dioxide (nTiO2) or nano cerium oxide (nCeO2) (0, 250, 500 and 1000 mg/L) to examine potential effects on germination and early seedling development. We modified a standard test protocol developed for soluble chemicals (OPPTS 850.4200) to determine if such an approach might be useful for screening engineered nanomaterials (ENMs) and whether there were differences in response across a range of commercially important plant species to two common metal oxide ENMs. Eight of 10 species responded to nTiO2, and 5 species responded to nCeO2. Overall, it appeared that early root growth may be a more sensitive indicator of potential effects from ENM exposure than germination. The observed effects did not always relate to the exposure concentration, indicating that mass-based concentration may not fully explain developmental effects of these two ENMs. The results suggest that nTiO2 and nCeO2 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, standard germination tests, which are 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.
