Effects of ionic, micro- and nano-sized iron on Lepidium sativum as a reference biological model

Engineered nanomaterials are at the forefront of ecotoxicologist agendas due to their widespread use in a broad range of industrial and domestic sectors. Actually, they are manufactured in increasing amounts year-by-year. Particularly, nanoscopic zerovalent iron started to be used in various countries around the world for land and groundwater remediation presenting, apparently, encouraging removal rates particularly with organic compounds. Indeed, the use of iron in remediation activities mainly via the Fenton reaction is considered a sort of common practice. Nevertheless, since now few data are available about the potential adverse effects of the release, even if controlled, of iron within the ecosystem. Terrestrial plants may be considered as interesting biological models for assessing its potential impacts. The effect of ionic, micro- and nano-sized iron were compared using Lepidium sativum as reference biological model. Germination, elongation and biomass production inhibition were taken into consideration as endpoints. Besides the full physico-chemical characterisation of the selected chemicals, neutron activation offered the possibility to label them in a way that avoids surface modification and permits both localization and quantification within the model organisms. The main results showed the following toxicity trend: nano-sized iron < micro-sized iron < ionic iron.