title: Elevated levels of DNA-protein crosslinks and micronuclei in peripheral lymphocytes of tannery workers exposed to trivalent chromium.
abstract: DNA-protein crosslinks (DPC) are a promising biomarker of exposure to hexavalent chromium, a known human carcinogen. Although trivalent chromium is considered to have much lower toxicity, the risk involved in chronic exposure is uncertain. DPC may be a useful tool in clarifying this risk, by signaling an exposure of body tissues to biologically active forms of chromium. DPC quantification was carried out in lymphocytes of a group of tannery workers exposed to trivalent chromium, a small group of manual metal arc stainless steel welders exposed to hexavalent chromium and a control group. This biomarker was compared with the frequency of micronuclei in cytokinesis blocked peripheral lymphocytes as a biomarker of cytogenetic lesions and total plasma and urine chromium levels as an index of exposure. The results indicate a significant increase in the formation of DPC in tannery workers compared with controls (0.88 +/- 0.19 versus 0.57 +/- 0.21%, P < 0.001, Mann-Whitney test) and an even higher level of DPC in welders (2.22 +/- 1.12%, P = 0.03). Tanners showed a significant increase in micronucleated cells compared with controls (6.35 +/- 2.94 versus 3.58 +/- 1.69 per thousand, P < 0.01), whereas in welders this increase was not significant (5.40 +/- 1.67 per thousand ). Urinary chromium was increased in both groups, with a greater increase observed in tanners compared with controls (2.63 +/- 1.62 versus 0.70 +/- 0.38 microg/g creatinine, P < 0.001) than in welders (1.90 +/- 0.37 microg/g creatinine, P < 0.005). Plasma chromium was also increased in both groups (tanners 2.43 +/- 2.11 microg/l, P < 0.001, welders 1.55 +/- 0.67 microg/l, P < 0.005 versus controls 0.41 +/- 0.11 microg/l). In summary, chronic occupational exposure to trivalent chromium can lead to a detectable increase in lymphocyte DNA damage which correlates with a significant exposure of the cells to the metal.
authors.affiliation: Department of Genetics, Faculty of Medical Sciences, New University of Lisbon, R. da Junqueira 96, P 1349-008 Lisbon, Portugal.
authors.forename: M G
authors.initials: MG
authors.lastname: Medeiros
authors.forename: A S
authors.initials: AS
authors.lastname: Rodrigues
authors.forename: M C
authors.initials: MC
authors.lastname: Batoréu
authors.forename: A
authors.initials: A
authors.lastname: Laires
authors.forename: J
authors.initials: J
authors.lastname: Rueff
authors.forename: A
authors.initials: A
authors.lastname: Zhitkovich
mesh_terms: D000328:Adult; D002412:Cations; D002857:Chromium / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D003404:Creatinine / Q000097:blood; D003432:Cross-Linking Reagents / Q000009:adverse effects*; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D004785:Environmental Pollutants / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000737:chemistry* / Q000648:ultrastructure; D008297:Male; D015162:Micronucleus Tests; D008875:Middle Aged; D016273:Occupational Exposure; D011506:Proteins / Q000187:drug effects; D012907:Smoking / Q000453:epidemiology; D013633:Tanning; D014896:Welding
chemical_list: D002412:Cations; D003432:Cross-Linking Reagents; D004785:Environmental Pollutants; D011506:Proteins; D002857:Chromium; C074702:chromium hexavalent ion; D004247:DNA; D003404:Creatinine