In a study published in 2022 in the journal Particle and Fibre Technology, researchers examined the impact of maternal exposure to titanium dioxide nanoparticles in newborn offspring mice. They found that “a chronic exposure to TiO2 NPs during pregnancy alters the respiratory activity of offspring, characterized by an abnormally elevated rate of breathing.” Breathing was also shown to be “significantly and abnormally accelerated,” and the ability for neural circuitry to effectively adjust breathing rates was impaired. The researchers concluded: “Our findings thus demonstrate that a maternal exposure to TiO2 NPs during pregnancy affects the normal development and operation of the respiratory centers in progeny.”

Prof. Matthew Wright, chair of EFSA’s working group on E171, noted: “Although the evidence for general toxic effects was not conclusive, on the basis of the new data and strengthened methods we could not rule out a concern for genotoxicity and consequently we could not establish a safe level for daily intake of the food additive.”