Because of its confirmed carcinogenic properties (Agency for Toxic Substances and Disease Registry, 1997; Shim et al., 2002), the standard set by United State Environmental Protection
Agency (USEPA) 2002 and Occupational Safety and Health Administration (OSHA) for benzene in drinking water is 5 lg L1,which means this is the maximum airborne concentration of benzene
calculated as an 8-h time-weighted average (Rahul et al.,2012).