What are the concerns over the use of nanoparticles in sunscreens?

The basis for most concerns over the use of nanoparticles in sunscreens relates to their small size.

These size-related concerns include the potential for nanoparticles to:

• penetrate human skin and enter the body
• get inside living cells
• interact directly with biomolecules and alter their properties.

There are also concerns about the ability of metal oxide nanoparticles to emit reactive species (free radicals) upon absorption of ultraviolet (UV) radiation and visible light.

The potential concern is that emitted free radicals may damage membranes surrounding living cells, or directly react with biomolecules inside living cells.

For more information, refer to our work on Understanding Nanotechnology.