Send Orders for Reprints to reprints@benthamscience.net Current Medicinal Chemistry, 2014, 21, 3837-3853 3837 Toxicity of Nanoparticles Maria Antonietta Zoroddu 1,* , Serenella Medici 1 , Alessia Ledda 1 , Valeria Marina Nurchi 2 , Joanna I. Lachowicz 2 and Massimiliano Peana 1,* 1 Department of Chemistry and Pharmacy, University of Sassari, Via Vienna 2, 07100, Sassari, Italy; 2 Department of Chemical and Geological Sciences, University of Cagliari, Cittadella Universitaria, I-09042 Monserrato, Cagliari, Italy Abstract: Nowadays more than thousands of different nanoparticles are known, though no well-defined guidelines to evaluate their potential toxicity and to control their exposure are fully provided. The way of entry of nanoparticles to- gether with their specificities such as chemistry, chemical composition, size, shape or morphology, surface charge and area can influence their biological activities and effects. A specific property may give rise to either a safe particle or to a dangerous one. The small size allows nanoparticles to enter the body by crossing several barriers, to pass into the blood stream and lymphatic system from where they can reach organs and tissues and strictly interact with biological structures, thus damaging their normal functions in different ways. This review provides a summary of what is known on the toxicol- ogy related to the specificity of nanoparticles, both as technological tools or ambient pollutants. The aim is to highlight their potential hazard and to provide a balanced update on all the important questions and directions that should be fo- cused in the near future. Keywords: Nanoparticles, toxicity. INTRODUCTION “Nano” prefix in the nanoparticle (NP) word comes from the ancient Greek language and means “dwarf”, much smaller than most particles, indicating particles whose di- ameter is lower than 100 nanometers (10 -9 m), ranging from 1 to 100 nm [1-5]. A plethora of chemicals of different shapes and proper- ties can be classified as nanomaterials, the most prominent ones being heavy metals as nickel, cadmium, manganese, zinc, titanium, gold, antimony, silicon and their metal oxides, carbon and others which can be engineered or incidentally released in the environment. Engineered man-made NPs have found several applica- tions mainly in biomedical fields for improving diagnostic tools and clinical treatments. Incidental NPs can be produced by a number of sources. They derive from industrial activities and can be found in there and in the surrounding environments. They are mainly generated from power plants by coal, natural gas and oil. Nano-scale particles can derive from incineration of solid waste, combustion of fossil fuels or traffic emissions. In these cases NPs can be a complex mixture of different chemical compositions. A complex NPs mixture could also be formed in military shooting ranges as a result of the explosion of bombs devel- oping very high temperatures; following this, all the *Address correspondence to this author at the Department of Chemistry and Pharmacy, University of Sassari, Via Vienna 2, 07100, Sassari, Italy; Tel: +39 079 229529; Fax: +39 079 229559; E-mail: zoroddu@uniss.it and peana@uniss.it surrounding materials may be pulverized, from the rocks to the soil, and easily transported as a fine suspension in air as well as in water. Inorganic and metallic powders so produced are often in- soluble and non-biodegradable particles: their small size allows them to be delivered in the whole environment, where they stick around forever. In Fig. (1) human exposure to NPs, main anthropogenic sources, their release in the work place and environment and the subsequent occupational or public exposure through sev- eral ways of entry and translocation into human body are reported. The focus on the NPs peculiarity stems from their nano- scale size that leads to a very high surface offered to all dif- ferent reactions. Despite the enthusiastic and promising applications in several fields of specific engineered NPs, several deleterious effects appeared that have become the topic of concern. In fact, both engineered and incidentally, unintentionally released NPs may share several common adverse effects on human health. In all cases, independently from their use and source, NPs may enter human body and accumulate in organs and tissues as foreign bodies. For that reason, recently, a new branch of science that has the aim to study the dangerous effects of nanomaterials on human health and environment has been named nanotoxicology [6,7]. This review tries to evaluate the unique peculiarities be- longing to particles of nano-scale dimensions, which should be taken into account to cast light on their toxic effects. Here what is known on the toxicology of NPs will be summarized, /14 $58.00+.00 © 2014 Bentham Science Publishers