MEASUREMENT OF DNA-PROTEIN CROSS-LINKS IN HUMAN-LEUKOCYTES FOLLOWING ACUTE INGESTION OF CHROMIUM IN DRINKING-WATER

Increased DNA-protein cross-linking (DPX) in circulating leukocytes ha s been proposed as a potential biomarker for exposure and genotoxic da mage caused by inhalation of certain reactive chemicals, such as hexav alent chromium [Cr(VI)]. This study was designed to determine whether ingestion of a single dose of potassium dichromate alone [Cr(VI)] or p otassium dichromate fully reduced to Cr(III) with orange juice (prior to ingestion) causes an increase in DPX of circulating leukocytes in h umans, Four adult male volunteers ingested a bolus dose of 5000 mu g c hromium in a 0.51 volume of water (10 p.p.m.), and blood samples were collected at 0, 60, 120, 180 and 240 min afterwards for analysis of DP X formation in circulating leukocytes, Results were compared to each p erson's own background concentration of DPX in leukocytes, Blood and u rine samples were also collected for up to 2 weeks following the dose to examine the pattern of uptake and excretion of chromium, The result s showed that there was no significant change in DPX observed followin g either Cr(VI) or Cr(III) ingestion, even though blood and urine chro mium measurements indicated systemic uptake of a substantial fraction of the ingested chromium, Since Cr(III) does not possess DPX-inducing properties while Cr(VI) does, these results suggest that the Cr(VI) wa s reduced to Cr(III) intragastrically prior to absorption or that the amount of Cr(VI) absorbed into the blood was insufficient to produce D PX, These results are consistent with prior research that indicated th at DPX would not occur following exposure to Cr(VI) except at very hig h doses.