Academic journal article Central European Journal of Public Health

Nanomaterials - a New and Former Public Health Issue. the Case of Slovakia

Academic journal article Central European Journal of Public Health

Nanomaterials - a New and Former Public Health Issue. the Case of Slovakia

Article excerpt

INTRODUCTION

Nanoparticles, nanomaterials and nanotechnology represent concepts that are increasingly used by professionals and lay people. This stems from the massive expansion of their development and use in recent years, which opens new opportunities in many fields of human activities.

The European Commission defines nanomaterial as a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or agglomerate and where, generally for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size ranging from 1-100 nm. Fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm should be considered as nanomaterials (1).

Why is this both new and former issue? Nanoparticles (NP) are present in the environment much longer than the last few decades - for example, as part of smoke accompanying volcanic activity or combustion of various materials. The NP concept includes also subcellular structures (nucleus of the cell, mitochondria, cell membranes), DNA macromolecules, viruses, etc. However, new profits but also risks are brought about by the targeted production of new NP that have not been met by living organisms. It may therefore happen that human defence mechanisms fail and would not be able to react appropriately to newly created particles and know how to prevent their potential negative effects. Each unknown and, in terms of biological effects, unexplored substance - as the toxicity of most engineered NP is unknown - may have a potentially harmful impact on individuals and population health. Despite the unquestionable positives, it is necessary to take into consideration the potential risks resulting from their long-term deleterious exposure.

CURRENT KNOWLEDGE

Characteristics of Nanoparticles

A comparison between the size of NP and other known objects is shown in Figure 1 (2). As the dimensions of NP are close to the dimensions of basic material particles (atoms, molecules), quantum phenomena start to apply and NP acquire unique physical and chemical characteristics, which are not shown in the substance in the form of larger particles (3). In particular, quantum restriction on the movement of electrons in nanoparticles and a relatively large surface of the nanoparticles as a place of interaction of nanoparticles with the environment are considered to be the direct causes of changes in the properties (4). For instance, one microparticle having a diameter of 60 pm (human hair) cor- responds to the weight of 1 billion nanoparticles of 60 nm in diameter, the surface of which is a thousand times greater than the considered nanoparticle. Changes in the physicochemical properties concern in particular the change of solubility in polar and non-polar solvents, changes in electrical potential and electrical conductivity, changes in colour and fluorescence, changes in refractive index and absorption of light. A significant change in chemical reactivity: increased reactivity is associated with an increase in the surface energy of several orders of magnitude while reducing the volume of particles into nanoscale (4, 5).

The nanoparticles have spherical, tubular or irregular shape (6). NP properties depend primarily on their size. A substance consisting of NP has different properties than the same substance composed of larger particles, for example microparticles having the size of microns. Particles and nanoparticles of the same substance can have completely different effects on the human body. Also nanoparticles of different sizes may have different effects and different reactivity rate (6). A demonstrative example of that phenomenon is the pyrophoric behaviour of nanoiron that spontaneously ignites in contact with atmospheric oxygen (5).

Use of Nanoparticles

The production and use of intentionally prepared NP and nanomaterials (NMs) have increased rapidly over the last ten years: the total quantities delivered to the world markets are estimated at millions of tons per year with an annual increase in production of about 50%, which corresponds to about 10fold increase in six years. …

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