Full text
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| Author(s): |
Deise Nascimento Crispim dos Santos
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2012-11-09 |
| Examining board members: |
Gilka Jorge Figaro Gattas;
Danilo Fernandes Costa;
Adhemar Longatto Filho
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| Advisor: | Gilka Jorge Figaro Gattas |
| Abstract | |
Benzene is an aromatic hydrocarbon produced by the burning of natural products. The occupational exposure to benzene is characterized by industrial environments that use in their production processes. In the laboratories of Petroleum industry it is used in the pure form for analysis, and it is present as a contaminant in other products like gasoline, hexane, kerosene, toluene, etc. In Brazil the threshold limit value recommended by law in environmental exposure to benzene is 1 ppm. The hematological cancer is considered one of the main risk factors for the health of workers occupationally exposed to benzene and the use of biomarkers in monitoring these professionals has been suggested in different countries. The aim of this study was to assess different biomarkers in peripheral blood lymphocytes from 20 men workers chronically exposed to benzene in Petroleum Refinery and Steel Industry (18 workers with poisoning diagnosis), who were removed from workplace for periods ranging from five months to 27 years, with average age 46.8 ± 9.33 years old compared to a control group consisting also of 20 men, selected in Blood Banks (average age 45.7 ± 8.00 years old), with different occupations unrelated to the agent under study. In both groups were performed blood cell counts, cytokinesis-block micronucleus assay (CBMN), FISH assay in peripheral blood lymphocytes for translocation t(15;17), and molecular tests for evaluation of genetic polymorphisms in genes involved in benzene metabolism (MPO, NQO1, CYP1A1 e CYP2E1) and detoxification (GSTM1/GSTT1). Despite blood cell counts the statistical analysis performed by t-Student test revealed that workers exposed to benzene had leukopenia with a highly significant difference in leukocyte count (p<0.001), neutrophils (p<0.001), segmented (p<0.001), lymphocytes (p=0.013) and monocytes (p=0.010). The evaluation of red blood cells also revealed statistically significant differences between groups for RDW-CV (0.031), RDW-SD (0.008) and MPV (0.001). There were no differences between groups regarding the frequency of genetic polymorphisms in CYP1A1, CYP2E1, MPO, NQO1, GSTM1, and GSTT1. In the CBMN test the cell counts with MN and nucleoplasmic bridges was three times higher in exposed (1.95 ± 2.37) than in controls (0.65 ± 0.75), and the difference was considered statistically significant (t=2.33;38gl;p=0.024). In the FISH analysis for the PML/RAR? rearrangement the exposed workers also showed three times higher frequency of cells with at least one signal fusion (9.79 ± 9.54) in comparison to controls (3.95 ± 3.17), and the difference was statistically significant by the t-Student test (p=0.019). The results obtained in this study seem to agree with the literature data that show alterations in the stem cells of the bone marrow, resulting from occupational exposure to benzene, as well genotoxicity, identified by CBMN and FISH assay in peripheral blood lymphocytes. Although the number of subjects evaluated is reduced, and the occupational exposure includes other potentially genotoxic agents not only benzene, it is interesting to note that positive results were observed after an average of nine years of removal professional. The use of the CBMN test and the study of other translocations, not only PML/ RAR?, in lymphocytes of workers exposed may represent an important biomonitoring and less invasive monitoring of workers. The analysis of a major number of individuals, including those exposed to low concentrations of benzene, may be essential in validation of these biomarkers. (AU) | |
| FAPESP's process: | 09/01862-0 - Cytogenetics and Molecular Evaluation of Workers Exposed to Benzene. |
| Grantee: | Deise Nascimento Crispim dos Santos |
| Support Opportunities: | Scholarships in Brazil - Master |