The correct option is 2 and 3. Statement 1 is incorrect because nanoparticles naturally occur in the environment, such as in volcanic ash, smog, and other natural processes. Statement 2 is accurate as nanoparticles of metallic oxides, like zinc oxide and titanium dioxide, are commonly used in cosmetics for their UV protection properties. Statement 3 is also correct, as some nanoparticles released from commercial products can pose risks to human health and the environment, raising concerns about their safety and long-term effects, a topic often discussed in environmental science and public health literature relevant to UPSC studies.