Ecology & Safety ISSN 1314-7234, Volume 12, 2018 Journal of International Scientific Publications www.scientific-publications.net Page 174 EVALUATION OF THE POTENTIAL HAZARD OF MANUFACTURED METAL-BASED NANOMATERIALS TO HEALTH OF AQUATIC ECOSYSTEMS: STATE OF THE ART Irina Blinova 1 *, Marge Muna 1,2 , Aljona Lukjanova 1 , Anne Kahru 1,3 1 Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, Akadeemia 23, Tallinn 12618, Estonia 2 Department of Materials and Environmental Technology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia 3 Estonian Academy of Sciences, Kohtu 6, Tallinn, Estonia Abstract Rapidly growing production and use of engineered nanomaterials (NMs) is accompanied by increased emissions into the environment. Existing data gaps in the scientific knowledge on the fate of NMs in the environment and their potential biological adverse effects makes the evaluation of the environmental risks of NMs difficult if not impossible. We propose that the assessment of environmental risks and regulation and control of the release of metal-based NMs should be performed on the basis of total concentration of metals comprising these NMs. This would assure that the safe levels of NMs in the environment were not exceeded until enough environmentally relevant tests have been carried out for more realistic evaluations. Keywords: nanomaterials, toxicity, hazard, exposure, risk assessment 1. INTRODUCTION Rapidly growing production of metal-based nanomaterials (NMs) used in the different sectors of the world economy is inevitably accompanied by increased emissions of NMs into the environment via different pathways. According to Piccinno et al. [1] annual production volumes of NMs were highest for SiO2 (5500 tons) and TiO2 (3000 tons), followed by ZnO (550 tons) and carbon nanotubes (300 tons) whereas iron, cerium and aluminium oxide NPs as well as silver NPs were produced at about 55 ton level per year. The high production volume of metal-based NMs is the main reason why the current review focuses on metal-based nanomaterials. The modelling of the potential release of NMs has shown that nearly half of the NMs used in different applications will end their life cycle in the landfills and the rest mostly in the soil and water compartments [2]. NMs may reach the environment at different stages of their life cycle and via different pathways [3,4]. For example, aquatic ecosystems may be polluted via effluent discharges, directly when NMs are applied as pesticides or for remediation purposes [5] and also via secondary pollution, e.g. by swimming people spreading nanoTiO 2 -based UV-protection cosmetics into natural aquatic ecosystems. Recent report on the environmental risk assessment of nanomaterial use in Denmark pointed out that in addition to TiO 2 (mostly due to its high production volume and thus high environmental exposure), silver and CuO NMs may also pose a considerable risk to the aquatic environment close to the points of discharge, mostly due to their high toxicity to aquatic organisms [6]. According to the European Commission, the following definition of the term 'nanomaterial' has been recommended: 'Nanomaterial' means a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm-100 nm’ [7]. The physicochemical properties of NMs distinctly differ from the micro-sized (bulk) particles made from the same material due to the larger surface area per mass (specific surface area) leading to higher reactivity [8]. Due to unique properties of NMs, the hazard related to environmental pollution also may significantly differ from those of bulk (micro-size) materials as a result of