TOXICOLOGICAL PROFILE FOR CHROMIUM - Davidborowski.com

CHROMIUM 1402. HEALTH EFFECTSIn rats injected subcutaneously with 5.25 mg chromium(VI)/kg as potassium dichromate, most of thechromium in the tissues analyzed was found in the red blood cells with a peak level (63 µg chromium/g)achieved 24 hours after dosing. White blood cells were not analyzed for chromium content. Wholeplasma contained 2.7–35 µg/mL, and the plasma ultrafiltrate contained 0.15–0.79 µg/mL. Tissuedistribution 48 hours after dosing was as follows: 221.2 µg/g in renal cortex, 110.0 µg/g in liver,103.0 µg/g in spleen, 86.8 µg/g in lung, 58.9 µg/g in renal medulla, and 8.8 µg/g in bone, compared with2.28–5.98 µg/g in any tissues in controls. When rats were given repeated subcutaneous injections of1.05 mg chromium(VI)/kg/day, every other day for 2, 4, 8, 10, or 12 weeks, most of the chromium wasagain found in the red blood cells. However, while red blood cell levels rose progressively duringtreatment, levels as high as those seen after a single dose were never achieved, even when the total doseexceeded the dose in the single injection experiment 10-fold. The tissue levels of chromium determined48 hours after the last dose in the rats injected for 12 weeks were of the same order of magnitude as thoseseen after a single injection. These results suggest little tendency of soluble chromium(VI) compounds toaccumulate in tissues with repeated exposure (Mutti et al. 1979).In an in vitro study, whole blood samples were spiked with water-soluble chromium(VI) or chromium(III)compounds. The results showed a greater level of chromium inside erythrocytes after treatment withchromium(VI) compounds, compared to chromium(III) compounds. The investigators reported that bothchromium(VI) and chromium(III) compounds permeated the cell membrane, but only chromium(VI)compounds are taken up by erythrocytes and form complexes with intracellular proteins that could not beeliminated (Lewalter et al. 1985).The distribution of radioactivity was compared in mouse dams and fetuses following the intravenousinjection of the dams with 51 Chromium labelled-sodium dichromate(VI) or 51 chromiumlabelled-chromium(III) trichloride. In the maternal tissues, the highest levels of radioactivity from bothtreatments were achieved in the renal cortex, but the concentration of radioactivity in the tissues of damsgiven the hexavalent form was much higher than that of the dams given the trivalent form. The patternsof distribution of radioactivity in other tissues were identical regardless of administered valence state,with the skeleton, liver, kidneys, and ovaries accumulating the highest levels and the brain and muscle thelowest. The serum concentration of radioactivity after treatment with chromium(III) was 3 times higherthan that after treatment with chromium(VI). Radioactivity after treatment with both valence formscrossed the placenta, but the radioactivity from the hexavalent form crossed more readily. Forchromium(VI), .12% of the maternal serum concentration of radioactivity was found in the fetuses whenthe dams were administered sodium dichromate in mid-gestation (days 12–15). When the dams were