Consider the following statements: 1. Other than those made by humans, nanoparticles do not exist in nature. 2. Nanoparticles of some metallic oxides are u

1. A. 1 only
2. B. 3 only
3. C. 1 and 2
4. D. 2 and 3

Answer: D

Explanation

A nanoparticle is a small particle that ranges between 1 to 100 nanometres in size (diameter). Undetectable by the human eye, nanoparticles can exhibit significantly different physical and chemical properties to their larger material counterparts. Being much smaller than the wavelengths of visible light (400-700 nm), nanoparticles cannot be seen with ordinary optical microscopes, requiring the use of electron microscopes or microscopes with laser. Nanoparticles occur widely in nature and are objects of study in many sciences such as chemistry, physics, geology and biology. A significant fraction (by number, if not by mass) of interplanetary dust, that is still falling on the Earth at the rate of thousands of tons per year, is in the nanoparticle range; and the same is true of atmospheric dust particles. Many viruses have diameters in the nanoparticle range. Iron oxides/sulfides, silver, and gold are some of the representative examples of naturally- occurring nanoparticles in the environment. Hence statement 1 is not correct. Many cosmetic products used in our daily life are made with the assistance of nanotechnologies. Among metal and metal oxide nanoparticles (NPs) potentially present in cosmetics, those containing titanium dioxide and zinc oxide are common ingredients added to obtain a sufficient sun protection. The addition of silver and gold NPs is also mentioned to increase the antimicrobial and healing properties of some cosmetic formulations. Hence statement 2 is correct. The exposure of nanoparticle to environment and human can be described through different mechanisms. Primarily occupational exposures occur to workers (including engineers, scientists, and technicians) during the research-scale synthesis and commercial production of nanomaterial- based products. This exposure mainly results from handling of raw materials while carrying out reactions through the equipment. Characterization of resulting material, packing, and transportation can be other sources of this type of exposure. At the second stage, consumers are exposed to such nanomaterial during usage and application and it may lead to harmful and toxic effects. Hence statement 3 is correct.