Fecal and urinary excretion of65Zn post-IT instillation of65ZnO and SiO
-coated65ZnO NPs. Data are estimated cumulative urinary or fecal excretion of 65Zn over 28 days. The predominant excretion pathway was via the feces. Approximately half of the instilled 65Zn was excreted in the feces in both groups over 28 days (A). Only about 1% of the 65Zn dose was excreted in the urine (B).