Mice chronically exposed to high concentrations of hexavalent chromium (Cr(VI)), as sodium dichromate dihydrate (SDD), in drinking water develop duodenal tumors (NTP, 2008). In our recent publication in Toxicological Sciences, we reported that mice exposed to Cr(VI) for 90 days exhibited significant decreases in the reduced-to-oxidized glutathione (GSH/GSSG) ratio (Thompson et al., 2011). The GSH/GSSG ratio is well recognized as an indicator of cellular redox status (Schafer and Buettner, 2001). GSH is present in cells at mM concentrations and is likely a key reductant of Cr(VI) (De Flora and Wetterhahn, 1989). At study termination, the GSH/GSSG ratio in the duodenum was significantly decreased at ≥ 14 mg/l SDD. Stern asserts that “at face value, one might conclude from this report that 14 mg/l is a threshold for saturation of the reductive capacity of the mouse stomach.” In our view, the lack of statistical significance at < 14 mg/l does not demonstrate that ingested Cr(VI) was entirely reduced in the stomach but simply that the effect on the GSH/GSSG ratio in the duodenum was not statistically significant. Like any study, a larger sample size would have greater power to detect differences among treatment groups. We certainly did not state or imply that, based on the GSH/GSSG ratio data, there is a threshold for Cr(VI) reduction in the mouse stomach at 14 mg/l SDD.