SYSTEMIC UPTAKE OF CHROMIUM IN HUMAN VOLUNTEERS FOLLOWING DERMAL CONTACT WITH HEXAVALENT CHROMIUM (22 MG L)/

This study examined the systemic uptake of chromium in four human volu nteers following three hours of contact with water containing hexavale nt chromium [Cr(VI)] at a concentration of 22 mg/L. Volunteers were im mersed below the shoulders in water at 91 +/- 2.5 degrees F. On the da y prior to the experiment and for five days afterwards, samples of uri ne, plasma, and red blood cells (RBCs) were collected and analyzed for total chromium. Red blood cell chromium concentrations were used as a specific biomarker for systemic uptake of Cr(VI). Although total chro mium concentrations in RBCs and plasma increased relative to historica l background concentrations on the day of exposure, no sustained eleva tion of chromium concentrations was observed in RBCs or plasma of the volunteers tested. Since absorption of chromium in the hexavalent stat e would result in the irreversible binding of Cr(VI) to hemoglobin wit hin the RBC (manifested as a sustained elevation of total chromium con centrations in the RBC), the pattern of blood uptake and urinary excre tion observed was consistent with uptake and distribution of chromium in the trivalent state. Small increases were observed in the concentra tion of total chromium in urine within 48 h of exposure, indicating th at some trivalent chromium [Cr(III)] may have penetrated the skin at a rate of about 3.3 x 10(-5) to 4.1 x 10(-4) mu g/cm(2)-h. In short, th e data indicated that a 3-h contact with Cr(VI) at concentrations in w ater plausible for environmental exposure (e.g., swimming) was not exp ected to result in systemic uptake of measurable amounts of Cr(VI), al though a small quantity of Cr(VI) may have penetrated the skin where i t was subsequently reduced to Cr(III) prior to systemic uptake.