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?

Statement 1 is incorrect. Nanoparticles exist abundantly in nature. They can be formed through various natural processes, such as volcanic eruptions (volcanic ash), forest fires (soot), erosion (mineral dust), and even biological processes (e.g., proteins, viruses). Thus, they are not exclusively human-made.

Statement 2 is correct. Nanoparticles of metallic oxides like titanium dioxide (TiO2) and zinc oxide (ZnO) are commonly used in cosmetics, especially in sunscreens. Their nano-size allows them to be transparent on the skin while still providing effective UV protection.

Statement 3 is correct. There are growing concerns regarding the potential environmental and human health risks posed by engineered nanoparticles (ENPs) from commercial products. Once released into the environment, they can interact with biological systems in ways that are not yet fully understood, potentially leading to toxicity or other adverse effects in humans, animals, and ecosystems.

Therefore, statements 2 and 3 are correct.