While some nanoparticles are human-made, naturally occurring nanoparticles exist, such as those found in volcanic ash or sea spray, invalidating the first statement. Many metallic oxides, like titanium dioxide and zinc oxide in nanoparticle form, are indeed utilized in sunscreens and other cosmetic products for their UV-blocking properties. The potential environmental and health impacts of certain nanoparticles released from commercial products are a subject of ongoing research and concern, as their small size can lead to different interactions with biological systems and the environment.