UPSC Prelims 2014 Q98: Science & Technology – Materials & Engineering
There is some concern regarding the nanoparticles of some chemical elements that are used
by the industry in the manufacture of various products. Why?
1. They can accumulate in the environment, and contaminate water and soil.
2. They can enter the food chains.
3. They can trigger the production of free radicals.
Select the correct answer
using the code given below.
- (a) 1 and 2 only
- (b) 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Explanation
Concerns about nanoparticles
Nanoparticles are particles of 1 to 100 nanometres.
Their tiny size gives them useful properties, and also risks.
| Statement | Verdict | Reason |
|---|---|---|
| 1. They can accumulate in the environment, and contaminate water and soil | Correct | They are hard to filter and slow to break down |
| 2. They can enter the food chains | Correct | Taken up by plants, plankton and fish |
| 3. They can trigger the production of free radicals | Correct | Their large surface area makes them reactive; free radicals damage cells and DNA |
Where nanoparticles are used:
| Product | Nanoparticle |
|---|---|
| Sunscreens | Titanium dioxide, zinc oxide |
| Antibacterial fabrics | Silver |
| Paints and coatings | Various metal oxides |
| Electronics | Carbon nanotubes |
They can also cross the blood-brain barrier and enter cells.
Answer: (d) 1, 2 and 3.
Why each option is right or wrong
- (a) Incorrect. They can also trigger free radicals.
- (b) Incorrect. They also accumulate in the environment and enter food chains.
- (c) Incorrect. They can also enter the food chains.
- (d) CORRECT. Nanoparticles accumulate, enter food chains and trigger free radicals.
Key point
Nanoparticle risks: persist in soil and water, enter food chains, generate free radicals, cross cell and blood-brain barriers.
Remember
Nanoparticles: accumulate, enter food chain, make free radicals.
Common mistakes
- Assuming something so small must be harmless.
- Not linking a large surface area to high reactivity.
- Forgetting that everyday products such as sunscreen contain them.
Exam tip
'They can ...' statements about a new pollutant are usually all true.
Sources
- Department of Science and Technology — Nano Mission: Guidelines and Best Practices for Safe Handling of Nanomaterials
- NCERT Class XII — Chemistry (Surface Chemistry)