1-Hydroxypyrene and interleukin-8 for biological monitoring of vehicle exhaust exposure and effects among gas-station workers

Air pollution encountered in many towns and cities throughout the world is associated with high levels of fuel vapors and motor vehicle-generated exhaust. A consistent association was reported between the levels of particulate matter and semi-volatile organic compounds in the ambient air with increasing mortality and morbidity. Although the epidemiological evidence is strong, there are yet neither established biological mechanisms to explain the toxicity in humans nor biologically established biomarkers for both exposure and severity of disease. This study was done to determine the impact of vehicle exhaust on the human airways among extensively exposed workers in few gas stations. The extent of exposure to polycyclic aromatic hydrocarbons [PAHs] is measured by estimating the level of 1-hydroxypyrene [1-OHP], a pyrene metabolite. Respiratory inflammation is clinically assessed and evaluated using pulmonary function tests. The impact of respired vehicle exhaust on the immunobiology of the respiratory system is evaluated by estimating the level of the cytokine interleukin-8 [IL-8] in serum, being used as an indication for respiratory inflammation and tissue damage. The study population consisted of 34 highway gas-station workers exposed to vehicle exhaust and 30 matched non-exposed office workers. The exposed population was further subdivided into a fueling group [n=22] working in petrol filling of cars and a car washing group [n=12] working in car cleaning. The study population was subjected to thorough clinical examination, pulmonary function testing and laboratory investigations. Measurement of the urinary 1-OHP level was done using the high performance liquid chromatography [HPLC] with electrochemical water detectors. As for the cytokine IL-8, estimation was done using quantitative sandwich enzyme-linked immunosorbent assay [ELISA]. Medical history and clinical examination revealed significantly higher frequency of repeated chest infections among the exposed group [41%] than among the control subjects [6.6%]. As for chronic bronchitis, asthmatic attacks and dyspnea, the results were higher among the exposed groups but with no statistically significant difference. Ventilation function tests revealed the presence of an obstructive affection among exposed workers correlating strongly with age and smoking habits but not with the duration of exposure. The level of FEV[1] /FVC ratio correlated with the level of 1-OHP that is the PAHs biomarker of exposure [r=-0.313; P<0.01]. The urinary 1-OHP was found to be significantly higher among the exposed population, but still no significant correlation was obtained with exposure duration. The serum IL-8 level was markedly elevated among the exposed workers and significantly correlated with FEF[25%-75%] [r = -0.263; P<0.05] revealing the presence of a high risk of chronic inflammation and lung cancer. Occupational exposure of workers in the gas stations to vehicle exhaust carries an increased risk for respiratory diseases such as repeated chest infections, chronic bronchitis and asthmatic attacks as proved by the presence of dyspnea and the decrement in pulmonary functions. Alteration of the immunological responses of the respiratory epithelium should be considered bearing a risk factor for lung cancer development later on in life. Using the urinary 1-OHP level as a biomarker for exposure and the serum IL-8 level for chronic inflammation and respiratory disease severity and progression should be further evaluated. Long-term impact on the environment needs to be properly investigated in addition to the implementation of protective measures aiming at reducing the occupational exposure to diesel-related polycyclic aromatic hydrocarbons

Effects of occupational exposure to mercury vapor on the thyroid hormones and glutathione peroxidase enzyme

Evaluation of the effect of elemental mercury [Hg[0]] vapor exposure on the plasma glutathione peroxidase enzyme [PGLPX] and its impact on the thyroid function as evidenced by changes in the level of free thyroxin [T[4]], free triiodothyronine [T[3]], free T[4] /free T[3] ratio as well as the thyroid stimulating hormone [TSH] level. The level of glutathione peroxidase enzyme was estimated using the PGLPX-enzyme immunoassay [EIA]. Serum concentrations of TSH, free T[4] and free T[3] were determined by radioimmunoassay. Assessment of the urinary mercury level was carried out using the atomic absorption spectrometry. The creatinine-corrected urinary mercury [U-Hg] was considered an index of current exposure. This study was carried out on a group of 20 workers exposed to mercury vapor for an average of 29.15 years during the process of mercury electrolysis in an explosive industry and on 12 matched control workers. The mean U-Hg in the exposed population was high [136.86 +/- 45.68 micro g. gm[-1] creatinine] versus 35.44 +/- 14.87 [micro g. gm[-1] creatinine in the control group. There was a remarkable statistically significant increase in the free T4 level among exposed subjects as compared to controls [mean 1.565 ngm dL-1 versus 0.950 ngm dL[-1]]. The free T[4] /free T[3] ratio was also higher in the exposed subjects, but no significant difference was obtained for the level of T[3] and TSH. As for the PGLPX, a highly significant decrease was obtained in the exposed population compared to the control. A significant association was found between increased U-Hg and decreased TSH as well as PGLPX fall. The drop in the level of TSH was shown to be affected by the duration of exposure as evidenced by the statistically significant negative correlation. Regarding PGLPX, there was a significant negative correlation with the level of urea, bilirubin, as well as the free T4 and the free T[4] /free T[3] ratio. The study could indicate a slight effect of occupational exposure to mercury vapor on the function of the enzyme type I iodothyronine deiodinase, as evidenced by increased free T[4] /free T[3] ratio, and on the PGLPX level, as evidenced by the marked drop in its plasma level. Selenium deficiency might be considered an intermediate step in the pathogenesis of these changes

Health profile of workers in the paint industry

In paint manufacture, there is unacceptably high chemical exposure with consequent effects on health. Raw materials used to manufacture paints constitute major chemical hazards to workers as a result of mechanical operations. This study is conducted on a group of workers in a paint industry in an attempt to assess the impact of the paints and coatings on health and on the clinical and laboratory parameters. Due to the high concentration of solvents in this industry, high incidence of renal impairment has been observed. The liver was less affected as evidenced by the serum transaminases level, though these were considered unreliable measures being unrelated to sub-clinical affection. Chest examination revealed the presence of some cases of chronic bronchitis and others with frequent asthmatic attacks. Immunological assessment revealed statistically significant elevation in the serum immunoglobulin E [IgE] among the exposed population. Contrarily, the IgG was not significantly elevated though positively correlating with the IgE level. The paint industry is, therefore, one of the most hazardous industries that need further investigations to keep the levels of toxic dust to minimum and set the precautions to protect the working population