title: Arsenic and breast cancer: a systematic review of epidemiologic studies.
abstract: BACKGROUND
  Arsenic is one of the heavy metals known to be a cause of cancer and many other serious human health problems. The International Agency for Research on Cancer (IARC), has classified arsenic as a Group 1 carcinogen. Studies were performed in different populations to investigate the association between arsenic and breast cancer and the present paper attempts to review these studies.
  
  
  METHODS
  Accessible electronic resources including, PubMed, Web of Knowledge, Science Direct and Scopus and Google Scholar were searched, with relevant phrases up to October 30, 2016. All articles were reviewed by two people separately and among them, original epidemiologic studies that investigated the association between breast cancer and exposure to arsenic were included.
  
  
  RESULTS
  Eventually seven articles were selected from 126 retrieved articles. Although three studies (one case-control and two ecological) were not able to show a significant affect, others provide some evidence of a relation between arsenic and breast cancer in specific subgroups.
  
  
  CONCLUSIONS
  Exposure to arsenic may increase the risk of breast cancer. The strength of this relation can vary due to regional and individual differences.
authors.affiliation: .
authors.forename: Narges
authors.initials: N
authors.lastname: Khanjani
authors.affiliation: .
authors.forename: Abu-Bakr
authors.initials: AB
authors.lastname: Jafarnejad
authors.affiliation: .
authors.forename: Leila
authors.initials: L
authors.lastname: Tavakkoli
mesh_terms: D001151:Arsenic / Q000633:toxicity*; D001943:Breast Neoplasms / Q000453:epidemiology*; D002273:Carcinogens; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D019216:Metals, Heavy
chemical_list: D002273:Carcinogens; D019216:Metals, Heavy; D001151:Arsenic
keywords: arsenic; breast neoplasms; environmental exposures; heavy metals