الفهرس 
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Abstract
Benzene, an aromatic hydrocarbon and a component of crude oil and gasoline, is produced at high levels and is widely used in the USA as an intermediate in the manufacture of plastics, resins, dyes, etc. It is known as one of the predominant air pollutants in the environment. Occupational exposure to benzene occurs through solvent exposures in the chemical industry, in petroleum refineries, oil pipelines, on ships and tankers, auto repair shops and bus garages.
Benzene is associated with multiple adverse health effects. It was shown to induce hematotoxicity in humans over 100 years ago. It is a cause of acute myeloid leukemia (AML) and myelodysplastic syndrome and a probable cause of other hematological malignancies, such as non-Hodgkin lymphoma, ALL, CLL and multiple myeloma.
This study aimed to evaluate the role of immunophenotyping in assessment of hematological changes in gas station workers.
This study was performed on 50 gas station workers exposed to benzene for more than 3 years not under immune-suppressant drugs, radiotherapy or chemotherapy or with immune-deficiency disease or malignancy and 20 healthy persons did not exposed to benzene.
In this study we found that 52% of subjects exposed to benzene suffered from headache, 36% of them suffered from pallor, 20% of them suffered from weakness, 18% of them suffered from loss of weight and 14% of them suffered from dizziness.
In this study we performed CBC, kidney function tests, liver function tests, ESR and CD3,CD4,CD8,CD16,CD56, CD5, CD10, CD19, CD2, CD34, ANTI HLA-DR, CD45, CD33, CD7, CD13 and CD4/CD8 ratio from peripheral blood samples by Flowcytometry for gas station workers exposed to benzene for more than 3 years and healthy subjects non exposed to benzene.
This study showed that WBCs, ALT, AST, TP, albumin, urea and ESR increase in gas station workers compared to non exposed healthy group. On the other side, hemoglobin level, HCT, MCH and platelet count decrease in in gas station workers compared to non exposed healthy group.
The immunophenotyping in this study showed that absolute values of CD56, CD10, CD2 and Anti HLA-DR increase in gas station workers compared to non exposed healthy group but CD3, CD4, CD5 and CD7 and CD4/CD8 ratio decrease in gas station workers compared to non exposed group with insignificant difference of CD8, CD16, CD19, CD34, CD33, CD45, CD22 and CD13 and NK cells (CD16+CD56).
In this study we found that absolute values of CD8 and CD13 showed statistically significant positive correlation with WBCs, absolute values of CD56 and CD10 showed statistically significant positive correlation with ESR.
In this study we found that absolute values of CD5 and CD7 showed statistically positive correlation with platelets count but CD22 showed statistically negative correlation with platelets count. Also, CD5 showed statistically positive correlation with AST and ESR.
As well as, CD45 showed statistically negative correlation with lymphocytes percentage.
Also, absolute values of CD4/CD8 ratio showed statistically significant positive correlation with hemoglobin level, hematocrite level, AST, ALT.
Conclusion & Recommendation
Abnormal effect of benzene exposure were found among gas station workers. Exposed workers showed variety of syptoms mainly headache, weight loss, weakness, dizziness and pallor. As well as it increase liver enzymes. It also showed significant changes in blood components as increase in WBCs count and decrease in HGB level and platelet count with an increase of absolute values of CD56, CD10, CD2 and anti HLA-DR and decrease in absolute values of CD3, CD4, CD5, CD7 and CD4/CD8 ratio. It also showed increase in ESR and urea level .
In view of the present study, we recommend the following:
• More studies with larger number of gas station workers are highly recommended to assess the hematological changes caused by benzene exposure.
• Gas station workers must have blood tests such as CBC, liver function, kidney function tests, ESR, CD10, CD56, CD4 and anti HLA-DR periodically every three months to discover any hematologicl changes in order to manage these cases properly.
• Any gas station worker show any abnormalities in periodic blood tests should be reffered to hematologist to be examined well and perform the necessary blood tests to exclude any hematological changes in addition.
• Preventive and screening measures are required to reduce effect of benzene on gas station workers. Establishing a clinic for periodic checkup and early detection of symptoms and hematological changes in gas station workers. In addition, health education programs can be introduced for gas station workers to increase their level of awareness of the drawbacks of exposure to benzene.