Food-grade silicon dioxide (SiO2), an engineered nanomaterial, has been commonly used in food and personal care products since 1942. Both regulatory agencies and industry claimed little (if any) toxicity of food-grade SiO2 till 2012. Recent discoveries suggest that food-grade SiO2 may be more toxic than previously assumed. Thus our objectives are to provide novel insights on food-grade SiO2 in regards to its occurrence, properties, and toxicity. We isolated and identified amorphous nano SiO2 in ten types of foods (e.g., chocolate powder, taco seasoning, probiotic supplements) by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX).We performed additional characterizations on six source materials of food-grade SiO2. TEM images of the food-grade SiO2 showed average diameters of 9-26 nm, and X-ray diffraction analysis confirmed anamorphous structure. X-ray photoelectron spectroscopy indicated the presence of silicon in different oxidation states on the surface (IV, and III). Dissolution studies using tap water showed higher solubilization of food-grade SiO2 than in nanopure water. Toxicity assessment using intestinal brush border microvilli showed an inhibitory effect (i.e., disruption of the brush border) of food-grade SiO2. Based upon the widespread occurrence of SiO2 in food and the potential release to sewer systems, we are conducting additional work on the occurrence and characterization of SiO2 in sewage and treated wastewater.

Prospecting silicon dioxide in foods: Occurrence, characterization, and toxicity

249th National Meeting (2015)

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