Can chromium in Red Blood Cell be an indicator of exposure to hexavalent chromium? An In vitro investigation

Although workers may be exposed to chromium metal, Cr(III) compounds, and Cr(VI) compounds at workplace, only Cr(VI) compounds are of primary concern in terms of possible hazards. Medical surveillance and biomonitoring can help to protect workers’ health.
Cr(VI) ions, after uptake via ingestion, inhalation and/or percutaneous diffusion are carried in the blood and penetrate into the red blood cells. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the red blood cells represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. Whereas chromium measurement in urine and whole blood (and plasma) is indicative of a recent chromium exposure, chromium in RBC is attributable to Cr(VI) exposure and covers through RBC life time, a longer period of exposure. Before proposing Cr in RBC as a Biological Exposure Indicator to Cr(VI), in vitro studies are necessary to assess the reliability of this indicator.
The study checks the relation between chromium added to blood sample and chromium found in RBC, in plasma and in lymphocytes. The influence of chromium oxidation state (3 and 6), the speciation (chromate/dichromate and counterions), incubation time and temperature, of Ascorbic Acid concentration and different blood samples were investigated. Until now, none of the studied parameters showed a big influence on the correlation between hexavalent chromium added to blood samples and chromium in RBC.
In conclusion, our findings reinforce the idea that Cr in RBC should be investigated seriously as an Biological Exposure Indicator to Cr(VI) even if in-vivo studies are still needed to integrate our knowledge of Cr(VI) toxicokinetics. A single determination of chromium concentration in RBC would permit the biomonitoring of critical cases of Cr(VI) exposure.