Think small. Smaller. No, really, really small. It’s unlikely your imagination has yet approached the scale of nanotechnology, a field that deals with particles mind-bogglingly tiny. Nanotechnology creates miniscule particles that perform differently, physically and chemically, than their larger, natural counterparts. It’s a multibillion-dollar industry with applications in medicine, cosmetics, supplements, food production, and more, but it’s currently unregulated by the FDA—and that has some people hugely worried.

Sunscreen using titanium dioxide nanoparticles has come under particular scrutiny. “If you make these particles smaller with nanotechnology, the titanium becomes colorless, which manufacturers and consumers prefer,” says Kantha Shelke of Corvus Blue, a nutrition science consulting firm. Researchers are studying whether these nanoparticles may absorb into the bloodstream and what effect that may have. Opinions are mixed: In 2004, a European cosmetic regulatory panel decided that nanotech sunscreens posed “potential” penetration concerns and DNA damage, but a 2006 review in Australia contradicted those findings. Now a new study published in Cancer Research indicates that ingestion of titanium dioxide nanoparticles in food colors, vitamins, and additives could increase risk of cancer and genetic disorders, prompting researchers to advise against spray-on sunscreen. The Environmental Working Group has called for scientific risk assessment of all sunscreens, and full labeling of nano-scale ingredients so consumers can make informed choices. In November 2009, the Materials Committee of the National Organic Standards Board recommended prohibiting nanotechnology in organic production, processing, and packaging; more meetings on the topic are scheduled this spring.

Nano numbers

Nanometer: one-billionth of a meter

Pinhead: 1 million nanometers

Single ragweed pollen: 20,000 nanometers

Single blood cell: 2,500 nanometers

13,000: Current U.S. patents that contain the descriptor “nano”