Influence of free radicals on cardiovascular risk due to occupational exposure to mercury.

This study was designed to investigate the relation between occupational exposure to mercury and cardiovascular risk, as well as free radicals. The study subjects included 30 male workers exposed to mercury from a fluorescent lamp plant in Alexandria after exclusion of 12 workers with conditions that may bias the results. A matched control group of 20 male subjects were selected from a food industrial plant. The participants were subjected to interview, clinical examination, electrocardiography and R-R deep breathing variability test as a measure of cardiac autonomic function. Spot urine and venous blood samples were collected to measure mercury levels. Free radicals related markers were measured in serum namely lipid peroxide, superoxide dismutase (SOD) activity, catalase activity and glutathione S-transferase. Results showed significant longer electrocardiographic Q-Tc interval, which is corrected to heart rate, in exposed workers than in controls (p=0.002). The R-R deep breathing variability indices were significantly increased among exposed workers in comparison to controls (maximal variation (MV) ratio, p=0.024 & MV rate, p=0.019). The mercury levels in both urine and blood of exposed workers were significantly higher than controls (p<0.0001), with mean levels exceeding the permissible limits. Free radicals related markers revealed significant higher level of lipid peroxide, as well as significant lower levels of SOD activity, catalase activity and glutathione S-transferase among exposed workers than among controls (p<0.0001 for all). Independent relations were observed between Q-Tc and lipid peroxide, and between MV rate and SOD and catalase activities among exposed workers after adjustment for the confounders by multivariate regression analyses. These findings may suspect a cardiac autonomic dysfunction probably related to free radicals in mercury exposed workers. Also, it may through light on some preventive implications.

Environmental factors and health problems among workers of the national project in Toshka.

The National Project in Toshka is a recognized agricultural one, as well as a comprehensive developmental project. The present study was carried out to investigate environmental factors and health problems among workers in this National Project. Environmental levels of vibration, noise, heat stress, total suspended particulates and respirable dust were measured in the different activities of the project during May 2000. The health records of Behera Company Incorporation, the project main implementing contractor, in the period 1997-1999 were analyzed. Workers were classified according to the nature of occupational exposure into three groups namely; earth workers, concrete workers, and services and administration workers. Records of occupational accidents of the same group of workers and in the same period were analyzed as well. Results showed that all the measured environmental factors were within the permissible levels of exposure in the different project activities. Workers showed a significant lower rate of total health problems in the last studied year (1999) as compared to the previous two years (1997-1998) (p=0.001). Prevalence rates of musculoskeletal disorders, urinary tract troubles, ear-nose-throat (ENT) problems and chest problems were significantly higher in earth and concrete workers than in services and administration workers (p=0.001, 0.011, 0.036 and 0.044, respectively). Both occupational accident frequency and severity rates were very low in comparison to other major construction projects such as the High Dam. These rates showed decreasing trends throughout the studied years; however, relatively higher rates were observed among earth workers than the other groups. Miscellaneous wounds were the commonest presentation of occupational injuries among the three occupational groups. In conclusion, the current use of modern technology accounted for the low levels of enviro mental exposure factors, as well as the high safety standards. Workers showed a significant degree of acclimatization to work in this region; therefore, inhabitants and workers should be encouraged to engage this new community. The low rates of health problems among workers observed in this study reflected a satisfactory level of medical services. Preplacement and periodic medical examinations of construction workers aught to consider musculoskeletal, urinary tract, ENT and chest conditions among them.