A new study has found that metal oxide nanomaterials, such as titanium dioxide (TiO2), which is widely used in food, lollies, sunscreens and other cosmetics, “caused nonlethal, significant changes” to the microbial community in human gut. The scientists raised concerns that such changes “may be related to overall health effects.”

The study estimates that over 15000 metric tons of titanium dioxide, 3700 metric tons of zinc oxide and 300 metric tons of cerium oxide nanoparticles enter wastewater systems with the majority of the nanoparticles discharged from the wastewater treatment plants.

These three nanoparticles were investigated because of their widespread use in consumer products and because of their potential to occur in treated drinking water. These nanoparticles have been shown to have toxic but nonlethal effects on organisms and the scientists wanted to determine whether these nanoparticles were toxic to gut microbiota. The scientists observed that “the role of the gut microbiota is so prominent in human health that researchers have found links between gut microbes and numerous diseases.”

The study clearly raises concern regarding the health impacts of some commonly used nanoparticles. The obvious question is how will regulators respond to this study and the growing body of evidence of potentially adverse impacts associated with nanoparticles?