Fecal and urinary excretion of65Zn post-gavage of65ZnO and SiO
-coated65ZnO NPs. Data are estimated cumulative urinary or fecal excretion of 65Zn over 7 days. Similar to the IT-instilled groups, the predominant excretion pathway was via the feces. Ninety five % of the instilled 65Zn was excreted in both groups by day 7 (A). Only 0.1% of the 65Zn dose was excreted in the urine (B).