Properties of nanoparticles
Nanoparticles or nanos are particles with at least one dimension in the range of 1–100 nanometres (nm). The resolution of the human eye is more than a thousand times lower – 100,000 nm is equal to 0.1 mm, which is about the thickness of a sheet of paper.
Nanos can be divided into natural and man-made ones based on their formation. Natural nanos are formed, for example, during volcanic eruptions and forest fires. Viruses are also nano-sized. Man-made nanos are purposefully developed according to their desired properties. Their safety for health and the environment has not yet been proven.
With today's possibilities, nanos can be used in any field where any material is used: dirt-repellent and non-wrinkling clothing, self-cleaning windows, more fuel-efficient engines.
Nanos can be programmed – for example, insecticide can be ‘packaged’ into nanos, which ‘open’ and release the poison only in the insect's stomach, thus reducing unwanted effects on other organisms.
Of the nanotechnological materials, the average person is most exposed to UV-protective cosmetics. While a sunscreen containing larger particles of titanium dioxide (TiO2) or zinc oxide (No) leaves a whitish layer on the skin, a cream containing nanoparticles of the same substances appears transparent because the nanos scatter less visible light.
Health effects
The properties of nanos, which make them so special, make it equally difficult to determine their effects. Nanos must be seen as a completely new type of substance.
Nanos affect organisms in both good and bad ways differently than larger particles of the same substances. Because research must take into account the effects of all possible contributors, it takes time to establish scientifically proven claims.
Researchers have identified the fourteen most harmful nanomaterials that should be further researched as a matter of priority in terms of safety: nanosilver, nanoiron, nano-TiO2, -Al2O3, -CeO, -ZnO, -SiO2, nanoclay, carbon black nanopowder, C60 fullerenes, single-layer nanotubes, multilayer nanotubes, polystyrene and dendrimers.
The greatest health risk of nanoparticles to humans is through inhaling them. Due to their large specific surface area, nanoparticles can also bind, for example, toxic heavy metals and act as carriers, facilitating the entry of bound contaminants into cells.
The main respiratory hazards are carcinogenicity and chronic toxicity. There are currently no definitive data on toxicity to organs other than the lungs. There is even less information on the effects of nanomaterials on the skin and no evidence has been found of their effects through healthy skin.
Prevention
In view of the uncertainties regarding the health risks of nanomaterials and the limitations of the detection and measurement of nanomaterials in air, the precautionary principle should be applied. The recommended protection measures for airborne nanomaterials are the same as for aerosols and fine dust.
For future actions and activities, it is essential to develop methods for measuring exposure to nanomaterials in the workplace and to further assess the effectiveness of protective equipment such as ventilation, filters and personal protective equipment. Due to limited information on the effects of nanomaterials, the same personal protective equipment is currently recommended as for gases and aerosols.
Practical guidelines for the safe handling of nanomaterials are also needed in the workplace.
