In the field of nanotechnology, small might be better, but it's not necessarily safe. Biologists have found that a type of nanomaterial called buckyballs can damage brain cells in fish. Buckyballs are one of the many nanomaterials that scientists are auditioning for roles in products ranging from cheaper solar cells to better medicines.
Nanoscale materials are already used as pigments in cosmetics and sunscreens, and many more nanomaterials could reach consumers in the next decade or so. The exceptionally small size of these materials, whose dimensions may be only a few ten-thousandths of the width of a human hair, endows them with unique chemical and physical properties. However, their small size could also permit them to interact with living cells in unanticipated, potentially hazardous ways.