International Journal of Preventive Medicine (Int J Prev Med)2008-7802112012070410951100ENMD, MPH, Associate professor of occupational medicine, Center for Research on Occupational Diseases, Tehran University of Medical Sciences, Tehran, IranMD, RPSGT, Associate professor of occupational medicine, Center for Research on Occupational Diseases, Tehran University of Medical Sciences, Tehran, IranMD, Resident of occupational medicine, Center for Research on Occupational Diseases, Tehran University of Medical Sciences, Tehran, Iran20120704-http://ijpm.mui.ac.ir/index.php/ijpm/article/view/781http://ijpm.mui.ac.ir/index.php/ijpm/article/download/781/1176