2.1 Environmental Impact

Nanoparticles are not used as such in textile applications and are generally applied on to the substrates in the form of speciality coatings. Without sufficient data on the effects of the nanomaterial in their individual form and aggregates, the impact on environment remains highly hypothetical [10, 14, 15, 16]. Nanoparticles in the environment represent a new class of pollutants for which not much expertise is available.

Air borne nanoparticles have the tendency to float for very long periods and do not settle onto the surfaces easily. Unfortunately, larger surface also means that the nanoparticles can collect and transport pollutants in a larger way compared to any nanoparticles. Also, as the particle size decreases, the reactivity increases, harmful effects are intensified and harmless substances can assume hazardous characteristics. Combustible nanoparticles might cause an increased risk of explosion because of their increased surface area and potential for enhanced reaction.

Nanomaterials suffer from poor water solubility, favour the persistence of chemical in the environment and biological systems, where it can remain for long periods of time.

Even in soil, the nanoparticles may move in the unexpected ways, perhaps, penetrate the roots of the plants and enter into the food chain of humans and animals. Aggregates of nanomaterials are taken up by the living cells, which facilitate the access into the food chain. Nanomaterials are easily absorbed by the earthworms also.

2.2 Health Risks

Nanomaterials, in the human body and other living creatures, are likely to cause multiple problems to various physiological functions [10, 14, 17, 18, 19, 20, 21, 22]. One of the new properties of nanosized particles is their extreme mobility and unrestricted access inside the human body. Nanoparticles can have access through various routes into the body and across membranes such as the blood-brain barrier. During pregnancy, nanoparticles could cross placenta and enter fetus.

Nanoparticles

Nanoparticles harm living tissues, such as lungs through chemical reactivity or by damaging phagocytes, the scavenger cells that remove the foreign substances. Phagocytes become "over loaded" by nanoparticles and result in reduced functioning levels. Successive additions of particles are able to cause reactive damage, and antibodies such as bacteria can penetrate without hinderance. Nanoparticles can carry metals, carcinogenic hydrocarbons deep into the lung to cause asthma serious breathing problems and formation of free radicals. The surface reactivity of nanoparticles gives rise to "free radicals", which in turn can cause inflammation, tissue damages and initiate serious harms such as growth of tumors.

The adverse interactions between negatively charged nanoparticles with positively charged blood cells can result in blood clotting or clumping. The nanoparticles can enter the brain via olfactory nerves. Bucky Balls are found to cause brain damage in juvenile fish along with changes in gene function, which necessitates the assessment of the risks and benefits of this new technology. Juvenile largemouth (Micropterus Salmoides) bass exposed to 0.5 ppm aqueous uncoated fullerenes (C60) for 48 hours has showed a significant increase in lipids peroxidation in the brain, glutathione depletion in the gills [16]. In the case of nanofullerenes (C60), upto 500 nm, a very small concentration (20 ppb) is capable of killing half of the human liver and skin cells. Nano-fullerenes damage brain cells in fish and also halts the growth of bacteria [22].

Ingested nanoparticles can be, potentially, absorbed through 'Peyer's Plaques', the immune system lining the intestines, from where, the nanoparticles can gain entrance into the blood stream, transported through bone marrow, ovaries, muscles, brain, liver, spleen and lymph nodes.

Nanoparticle-protein complex affects the protein metabolism and cause protein degradation at the large surface area of these particles, which may lead to changes in the proteins and their functions. TiO₂ / ZnO nanoparticles present in the sunscreens are found to cause free radicals in skin cells and damaging DNA.