ABSTRACT
Radioactive sources and fixed or mobile X-ray equipment are used for both process and quality control in the metallurgical and fertilizer industries. Workers in the nuclear industry are a suitable sector of the populace for the direct estimation of radiation effects at low doses as they are typically monitored and restricted to effective doses of 100 mSv every 5 years. A dose-related increased mortality from circulatory diseases has been observed in some studies of nuclear industry workers, but it is unclear whether this reflects a real effect of radiation exposure or a spurious one. The aim of the present study was to detect the circulating endothelial progenitor cells [EPCs] in the peripheral blood and the frequency of micronuclei [FMN] among industrial radiographers occupationally exposed to ionizing radiation at the Steamer's Welding Company and EL Nasr Company for the manufacture of Fertilizers and Chemicals in Suez and Talkha, Egypt. Venous blood samples were obtained from 30 industrial radiographers exposed to x-rays during industrial procedures vs. 20 persons not exposed to ionizing radiation as control subjects. Blood samples were assayed for total and differential blood counts and cell phenotype of circulating EPCs, whose surface markers were identified as CD34, CD133 and kinase domain receptor [KDR], frequency of chromosomal aberrations [FCA], apoptosis percentage in circulating lymphocytes together with plasma stromal cell derived factor-1alpha [SDF-1alpha] and vascular endothelial growth factor [VEGF]. Results: The results of this study revealed a significant increase in FCA with respect to total number of dicentrics [0.09 +/- 0.03 vs. 0.0005 +/- 0.0001] and rings [0.01 +/- 0.0012 vs. 0] together with apoptosis percentage [7.3 +/- 2.8 % vs. 2.4 +/- 1.5 %] among industrial radiographers compared to control subjects respectively, indicating radiation exposure among such workers. Also a significant increase was observed in plasma SDF-1alpha [2750 +/- 370 vs. 2270 +/- 430 pg/ml], VEGF [157.9 +/- 16.9 vs. 137.5 +/- 12.6 pg/ml] among industrial radiographers compared to control subjects. Percentage of circulating mononuclear cells expressing CD34 [53 +/- 3.9 vs. 54.2 +/- 10.6/ 10[5] mononuclear cells], CD133 [82.4 +/- 4.8 vs. 54.2 +/- 10.6/ 10[5] mononuclear cells] and KDR [48.7 +/- 12.5 vs. 43.5 +/- 8.2/ 10[5] mononuclear cells] was significantly higher among industrial radiographers compared to control subjects. It is concluded that the industrial radiographers have increased numbers of circulating EPCs and increased levels of SDF-1 and VEGF, which denotes an increased capacity for tissue repair