This study is a meta-analysis of the previous epidemiological studies which investigated the quantitative estimates of the association between independent or combined exposure to noise and mixed organic solvents and hearing loss until October 2014. Overall, 15 studies with information on 7530 individuals (6% female) were included. Having assessed -by puretone audiometry -the adjusted odds ratio estimates for the association between solvents mixture exposure and the risk of developing hearing loss stood at 2.05 (95% confidence interval (CI): 1.44-2.9). Similarly, for subjects who were concurrently exposed to noise and solvents mixture, an OR of 2.95 (95% CI: 2.1-4.17) was obtained. There was some evidence of heterogeneity within each of the 2 exposure groups (p heterogeneity < 0.001). This heterogeneity was not explained by differences in strength of effect between duration of exposure, the number of solvent and exposure index in subgroups of solvents mixture exposure. Based on the available data, our analysis has provided the evidence of increased risk of developing hearing loss for workers exposed to organic solvents even at quite low concentration. Moreover, if such exposure is accompanied by noise, it will exacerbate the extent of hearing loss. Int J Occup Med Environ Health 2017;30(4):521-535

The aim of the present study was to evaluate the effects of occupational exposure to lead (Pb) and cadmium (Cd) on markers of oxidative stress in glazers in tile industries. Total antioxidant capacity (TAC), malondialdehyde (MDA), and the activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were determined in the blood of 80 subjects, including 40 glazers and 40 nonexposed subjects. Mean levels of blood Cd (8.90 ± 2.80 µg/L) and blood Pb (62.90 ± 38.10 µg/L) of glazers showed a significant increase compared with the control group. In the serum of glazers, the level of MDA was significantly higher and the level of TAC was significantly lower than the control group. We have noted a disturbance in the levels of antioxidants by a significant increase in the CAT activity and a significant decrease in the activities of SOD and GPx in the serum of glazers compared with the controls. Correlation analysis demonstrated that the serum MDA level and CAT activity were positively associated with the blood levels of Pb and Cd. Also, GPx and SOD were negatively correlated with blood Cd levels. The study clearly indicated that co-exposure to Cd and Pb can induce oxidative stress in glazers, resulting in increased lipid peroxidation and altered antioxidant enzymes.

Background: Smoking leads to changes in immune reaction and total antioxidant capacity. Smoking, through dysfunction of antioxidant system, plays an important role in the pathogenesis of inflammatory diseases. Objectives: The current study aimed at comparing salivary antioxidant capacity in smokers and non-smokers with severe chronic periodontitis. Patients and Methods:In this case-control study, among patients referred to Zahedan School of Dentistry without any systemic diseases, 64 patients with severe chronic periodontitis, including 27 smokers as the case group and 37 non-smokers as the control group, were selected. Stimulated salivary samples were collected and total antioxidant levels were evaluated through the Ferric reducing antioxidant power (FRAP) technique. All analyses were performed by SPSS (Ver.18) using Student's t-test, Mann Whitney test or analysis of variance (ANOVA) with significance level of 0.05 in all of the tests.

Background:In the printing industry, workers are occupationally exposed to an extensive variety of chemical solvents, including toluene and xylene. Biological monitoring is an essential tool for assessing occupational health risk. Objectives: The aim of the present study was to evaluate occupational exposure to toluene and xylene, as well as the biomarkers of exposure, in workers of the printing industry. Methods: The hippuric acid (HA) and o-, m-and p-methyl hippuric acids (o-, m-, p-MHAs) as the biomarkers of occupational exposure to toluene and each of the three xylene isomers, respectively, were determined in the urine samples of 84 subjects, including 44 printing workers and 40 non-exposed subjects. Results:The mean concentrations of toluene (37.64 ± 24.09 ppm) in the breathing zone of workers were higher, and the mean level of each of the three isomers of xylene (o-, m-, and p-xylene) was less than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs). In addition, the levels of urinary HA, o-MHA, and m-and p-MHA in the exposed group were 0.15 ± 0.04, 0.11 ± 0.01, and 0.19 ± 0.07 g g -1 creatinine, respectively. Printing workers showed a significant increase in the levels of urinary HA compared to the non-exposed subjects (P < 0.001). The correlation analysis demonstrated significant correlations between the intensity of the occupational exposure to toluene and xylene and the level of exposure biomarkers in the urine. Conclusions: The results indicated that although all the urinary biomarkers of exposure were below the Biological Exposure Indices (BEIs) recommended by ACGIH, the levels of the urinary metabolites of toluene and xylene were increased in printing workers. Therefore, monitoring of occupational exposure to toluene and xylene is helpful in the following-up of affected workers in the printing industry.

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