title: A Systematic Review on Exposure to Toxic and Essential Elements through Black Tea Consumption in Iran: Could It be a Major Risk for Human Health?
abstract: BACKGROUND
  Tea is the most popular nonalcoholic beverage worldwide. In recent years, some Iranian studies have shown the occurrence of toxic elements in fresh or dried tea leaves as well as in brewed tea. The present study aimed to ascertain the health risks associated with exposure to toxic and essential element through black tea consumption in Iran by systematically reviewing the accredited articles in the field.
  
  
  METHODS
  In order to obtain the relevant articles and academic databases, the search engines covering the specific disciplines were searched for the keywords, including tea, elements, heavy metals and determination. Having provided the complete list of sound articles, being conducted in Iran was considered as the inclusion criteria. Exclusion criteria were established as failure to provide information on the validity parameters and accuracy in the analytical methods. Choosing well conducted, reliable studies, analytical results for the concentration of each element in black tea were utilized in the determination of the hazard quotient (HQ) for the given element and the hazard index (HI) was then determined for all of the elements in each study.
  
  
  RESULTS
  Among the total studies, two were considered to be reliable. Aluminum was found to be the most abundant element in black tea marketed in Iran. Although the HQ for manganese was the highest among the studied elements, HQ and HI values for both toxic elements and essential elements were calculated as less than 1.
  
  
  CONCLUSIONS
  The hazard of excessive element intake through black tea consumption should be considered as negligible in Iran. However, related risk for manganese appeared to be more than toxic metals.
authors.affiliation: Department of Food Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Elahe
authors.initials: E
authors.lastname: Rezaee
authors.affiliation: Department of Food Technology, School of Nutrition and Food Science, Food Security Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Mirlohi
authors.affiliation: Department of Food Hygiene and Quality Control, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran.
authors.forename: Azizolah
authors.initials: A
authors.lastname: Fallah
authors.affiliation: Department of Food Technology, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Babashahi
keywords: Black tea; Iran; hazard index; hazard quotient; risk assessment; toxic and essential elements