Consider the following statements:

1. Other than those made by humans, nanoparticles do not exist in nature.

2. Nanoparticles of some metallic oxides are used in the manufacture of some cosmetics.

3. Nanoparticles of some commercial products which enter the environment are unsafe for humans.

Which of the statements given above is/are correct?

(a) 1 only

(b) 3 only

(c) 1 and 2

(d) 2 and 3

14. Ans: d

Explanation:

Nanoparticles are particles that exist on a nanometre scale (i.e., below 100 nm in at least one dimension). They can possess physical properties such as uniformity, conductance or special optical properties that make them desirable in materials science and biology.  Naturally occurring nanoparticles can be found in volcanic ash, ocean spray, fine sand and dust, and even biological matter (e.g. viruses).

Nanoparticles, can have the same dimensions as biological molecules such as proteins. In living systems, they may immediately adsorb onto their surface some of the large molecules they encounter as they enter the tissues and fluids of the body.

Hence, statement 1 is incorrect.

Nanotechnology has revolutionised industry. It is used to improve wide-ranging products, from cosmetics, toys and toothpastes to textiles and missiles. They are important constituents of sunscreen lotions. 

Some other uses of nanoparticles:

• Harvesting CO2: To help slow the climate-changing rise in atmospheric CO2 levels, researchers have developed nanoCO2 harvesters that can suck atmospheric carbon dioxide and deploy it for industrial purposes or convert it into useful products like methanol.
• Cleansing Water: Most toxic dyes used in textile and leather industries can be captured with nanoparticles. Appropriately designed magnetic nanomaterials can be used to separate pollutants such as arsenic, lead, chromium and mercury from water. In addition to removing dyes and metals, nanomaterials can also be used to clean up oil spills.  
• Nanoparticles can accelerate the anaerobic digestion of the sludge, thus making it more efficient in terms of duration and enhanced production of the biogas.

Hence, statement 2 is correct.

While nanoparticles have potential to solve environmental problems, the small size that makes them useful for environmental cleanup also raises special concerns about health and persistence in the environment.

Key factors in the interaction with living structures include nanoparticle dose, the ability of nanoparticles to spread within the body, as well as their solubility. Some nanoparticles dissolve easily and their effects on living organisms are the same as the effects of the chemical they are made of. However, other nanoparticles do not degrade or dissolve readily. Instead, they may accumulate in biological systems and persist for a long time, which makes such nanoparticles of particular concern.

Nanoparticles accumulate in the environment and kill the beneficial bacteria. Nanoparticles are released into the environment through the products they are used in like nanoparticles of zinc and titanium oxide damage DNA in cell lines, nanotitanium dioxide particles interfere with the genetic functioning of zebrafish embryos.

Hence, statement 3 is correct.

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