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This technical specification will provide guidelines for the toxicity of ZnO
nanomaterials in terms of physicochemical characteristics and reactive oxygen
species (ROS) properties and suggests that size of nanomaterials in not the sole
factor to be considered, thus, the development of appropriate criteria based on
morphological/physicochemical characteristics as well as synthesis procedures is
needed to evaluate the precise toxicity. Advanced electrospin resonance (ESR)
studies employing spin-trap agents and scavengers were adopted to distinguish the
different types of ROS released by nanomaterials. The technical specificaion
includes: (1) Scope (2) Terms and difinitions (3) Sample preparation methods (4)
ESR measurement procedure (5) Discussions on the result interpretation.

During last a few decades, the use of metal or metal oxide-based nanomaterials have
been dramatically increased in biomedical field and industrial applications. These
materials have special characteristics such as large specific surface area, fast
magnetic switching, and high solubility or dispersibility due to their extremely
small size. In contrast, studies on hazardous effects of nanomaterials are
currently under initial stage. In fact, there are no risk assessment standards for
evaluating the safety of manufactured nanomaterials.The safety of ZnO nanomaterials
has been not concretely demonstrated up to now.In this study, the toxic effects of
ZnO nanoparticles synthesized at different temperatures (room temperature and 60
C) were evaluated because the synthesis technique, especially the heating process,
strongly affect not only the physical morphology but also the surface conditions
(chemical bonding abilities or struc-tural defects) of the ZnO nanomaterials. To
understand relationship between ROS formation on the surface of nanomaterials and
their toxic mechanism, we will suggest ESR technique. This project would be
undertaken in WG3.