Tissue distribution of chromium in male Fischer 344 rats and female B6C3F1 mice exposed to chromium picolinate monohydrate in the diet for 2 years

Abstract

Chromium picolinate monohydrate (CPM), which contains chromium in the trivalent state (Cr III), is a popular dietary supplement, taken primarily for weight loss. As part of a 2-year NTP bioassay to assess the toxicity and carcinogenicity of CPM, total Cr was measured in tissues and excreta of male rats and female mice. CPM was administered in feed at concentrations of 0, 2000, 10000, and 50000 ppm. On days 4, 11, and 180, up to 10 animals per exposure group were removed from treatment and placed in individual metabolism cages for collection of urine and feces (from 0-24 and 24-48 hours); undosed feed and water were provided ad libitum. Liver, kidney, forestomach, glandular stomach, blood and plasma were collected on days 6, 13, and 182. Total Cr in each sample was quantitated by inductively coupled plasma-mass spectrometry. Most of the Cr eliminated was in the feces in both rats and mice, suggesting that absorption of Cr III was very low., The highest Cr concentrations were found in the kidneys of rats and livers of mice; kidney Cr concentrations in rats were up to 6-fold higher than in mice. The concentrations in glandular stomach and forestomach did not demonstrate a clear pattern across exposure concentrations or duration. Tissue Cr concentrations generally reached a plateau by 10000 ppm, indicating saturation of absorption or uptake. In general, Cr concentrations in erythrocytes and plasma reflected patterns seen in the tissues, but at much lower concentrations. The data from this study will aid in the interpretation of the bioassay results.