en تخصصي Special Systematic Review <div dir="ltr" style="text-align: justify;"><strong><em><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Introduction:</span></span></span></em></strong><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> Nickel (Ni) is one of the toxic heavy metals that exposure to it has been connected with chronic respiratory complications such as asthma, chronic bronchitis, lung cancer and heart disease. In this research, original studies that investigated occupational or environmental exposure to Nickel and&nbsp; measured nickel levels in human tissues were reviewed.</span></span></span><br> <strong><em><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Materials and Methods:</span></span></span></em></strong><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> In this study articles were reviewed systematically.&nbsp; National databases such as SID and Magiran&nbsp; as well as some international databases&nbsp; including PubMed,&nbsp; Web of Knowledge, Science Direct and Google Scholar were also searched; to extract studies conducted in Iran; until August 19, 2016.&nbsp; </span></span></span><br> <strong><em><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Results:</span></span></span></em></strong><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;"> Based on the results, industrial&nbsp; professions such as welding and plating who dealt directly with nickel were at a higher risk of contamination. In overall, residents in large polluted cities or taking dental treatments, had more nickel concentrations in their body than others.</span></span></span><br> <strong><em><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Conclusion:</span></span></span></em> </strong><span style="letter-spacing:.2pt;"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">Considering the high nickel contamination in some industrial workers, it seems necessary to do regular surveillance in these occupational groups and avoid unnecessary exposure to nickel as much as possible. Also, safer dental material should be used in orthodontics.</span></span></span></div> Nickel, Environmental Exposure, Occupational Exposure, Heavy Metals,Iran. 248 256 http://jehsd.ssu.ac.ir/browse.php?a_code=A-10-1-51&slc_lang=en&sid=1 Leila Tavakkoli No Department of Epidemiology and Biostatistics, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran. Abu-Bakr Jafarnejad No Non-communicable Diseases Research Center, Fasa University of Medical Sciences, Fasa, Iran. Narges Khanjani n_khanjani@kmu.ac.ir Yes Environmental Health Engineering Research Center, Kerman University of Medical Sciences, Kerman, Iran.