For almost two years, molecular biologist Bndicte Trouiller doused the drinking water of scores of lab mice with nano-titanium dioxide, the most common nanomaterial used in consumer products today. Halfway through, Trouiller became alarmed: Consuming the nano-titanium dioxide was damaging or destroying the animals' DNA and chromosomes. The biological havoc continued as she repeated the studies again and again. It was a significant finding: The degrees of DNA damage and genetic instability that [she] documented can be linked to all the big killers of man, namely cancer, heart disease, neurological disease and aging," says Professor Robert Schiestl, a genetic toxicologist who ran the lab at UCLA's School of Public Health where Trouiller did her research. Nano-titanium dioxide is so pervasive that the Environmental Working Group says it has calculated that close to 10,000 over-the-counter products use it in one form or another. Other public health specialists put the number even higher. It's "in everything from medicine capsules and nutritional supplements, to food icing and additives, to skin creams, oils and toothpaste," Schiestl says.