Evaluation of chromium in red blood cells as an indicator of exposure to hexavalent chromium: An in vitro study

Abstract

Chromium(VI) compounds are classified as carcinogenic to humans. Whereas chromium measurements in urine and whole blood (i.e., including plasma) are indicative of recent exposure, chromium in red blood cells (RBC) is attributable specifically to Cr(VI) exposure. Before recommending Cr in RBC as a biological indicator of Cr(VI) exposure, in-vitro studies must be undertaken to assess its reliability. The present study examines the relationship between the chromium added to a blood sample and that subsequently found in the RBC. After incubation of total blood with chromium, RBC were isolated, counted and their viability assessed. Direct analysis of chromium in RBC was conducted using Atomic Absorption Spectrometry. Hexavalent, but not trivalent Cr, was seen to accumulate in the RBC and we found a strong correlation between the Cr(VI) concentration added to a blood sample and the amount of Cr in RBC. This relationship appears to be independent of the chemical properties of the human blood samples (e.g., different blood donors or different reducing capacities). Even though in-vivo studies are still needed to integrate our understanding of Cr(VI) toxicokinetics, our findings reinforce the idea that a single determination of the chromium concentration in RBC would enable biomonitoring of critical cases of Cr(VI) exposure.

Effects of Chromium on Human Body

“…The level in red blood cells (RBC) in particular can indicate the exposure to Cr (VI) because of the selective properties of the RBC membrane [24].…”

“…Under normal circumstances (Table 2), the majority of chromium ions appear as trivalent Cr (III) or hexavalent Cr (VI) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][22][23][24]. An important distinction is that most of Cr (III) will be excreted in urine, while most of Cr (VI) will remain in the body [20].…”

Impacts of CAD/CAM Metallic Materials on Trace Metals and Biocompatibilities: An in vivo Study in Beagle Dogs

“…In addition, the main difference between whole blood and plasma is whether it contains blood cells. It has been discovered that some metal ions, such as chromium, can be selectively combined with red blood cells (Devoy et al, 2016), which presents a potential explanation for the differences in the trends of trace metal ion concentrations between whole blood and plasma.…”

HBM4EU chromates study - Usefulness of measurement of blood chromium levels in the assessment of occupational Cr(VI) exposure.

“…The sample was kept at +4 • C until transfer to the laboratory. To avoid hemolysis, separation of plasma and RBC was conducted, preferably within 8 h (and maximum 24 h) from the specimen collection, following the method described by Devoy et al (2016). Samples were centrifuged (10 min at 1000-2000×g or 5 min at 2700×g) and the supernatants containing the plasma and white blood cells were stored at +4 • C up to 7 days or at − 20 • C until analysis.…”

“…The common biomarker used for the biomonitoring of Cr exposure at workplace is urinary Cr (U-Cr). Although U-Cr allows to achieve a suitable evaluation of the exposure experienced by workers, some improvements are still required (Devoy et al, 2016). In fact, U-Cr is not specific for Cr(VI) since it measures exposure to both Cr(III) and Cr(VI).…”