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?

1. Incorrect. Nanoparticles also occur naturally—e.g., volcanic ash, sea spray, forest fires, and some biological processes produce them.

2. Correct. Metallic oxide nanoparticles such as titanium dioxide and zinc oxide are used in cosmetics and sunscreens.

3. Correct. Some nanoparticles from commercial products can enter air, water, or soil and may pose toxicity/health risks; hence they are considered unsafe in some cases.

Therefore, statements 2 and 3 are correct.