A Measure Of Titanium Dioxide

Used mainly as a whitening agent, titanium dioxide is a common additive in foods, paints, and personal care products. But scientists know little about how much TiO₂ appears in these products, and that lack of data hinders studies of the chemical’s potential health effects. Now researchers have conducted the first analytical study of TiO₂ in U.S. commercial goods, finding some products that contained almost 10% titanium by weight (Environ. Sci. Technol., DOI: 10.1021/es204168d).

“Risk assessors need more data on titanium exposure in people,” says Paul Westerhoff, of Arizona State University, who led the study. “Our study aims to fill in the gaps.”

Westerhoff and his colleagues analyzed foods, such as candy, chocolate, and dairy products, as well as personal care products, such as toothpaste and sunscreen. The researchers quantified titanium levels in the products using mass spectrometry. Concentrations in personal care products ranged from 1% to almost 10% titanium by weight. Among the 89 food products tested, white candies and other white-colored sweets, such as doughnuts, had the highest titanium levels, up to 340 mg per serving. Based on data on the consumption of such sweets from the National Diet and Nutrition Survey in the U.K., the researchers concluded that children consume two to four times as much titanium as adults do.

The team also found using scanning electron microscopy that 36% of the titanium in food was in nanoparticle form, with particles measuring less than 100 nm. Based on those observations, Westerhoff says food sources likely account for the vast majority of titanium nanoparticles discharged into the environment by wastewater treatment plants. Researchers next need to understand the health risks posed by this nanoscale fraction, he says.