title: Soils selenium level and esophageal cancer: an ecological study in a high risk area for esophageal cancer.
abstract: METHODS
  Golestan province, located in northeast of Iran, has been known as a high risk area for esophageal cancer (EC). This study was conducted to assess the relationship between soils selenium (Se) level and development of EC in this region.
  
  
  METHODS
  In this ecological study, 135 blocks were identified in Golestan province based on geographical altitude and longitude on the map. One soil sample was collected from the center of each block. Then we investigated Se concentration in soil samples by flame atomic absorption spectrometry. Statistical analysis was performed by the Pearson correlation test and Student t-tests. P-values of less than 0.05 were considered as significant.
  
  
  RESULTS
  The mean+/-SD of soils Se level in Golestan province was 3.7+/-1.61 mg/kg. There was a positive correlation between soils Se level and EC rates in this area (P=0.03) (Pearson correlation coefficient=0.19). Soils Se concentration was significantly higher in high (4.13 mg/kg) than in the low (3.39 mg/kg) EC rate areas (P=0.01).
  
  
  CONCLUSIONS
  We found high soils Se concentration and a significant positive relationship between soils Se level and EC rate in Golestan province of Iran. So, high soils Se level may play a possible role in developing EC in this area, specifically in Turkmensahra (very high EC rates).
authors.affiliation: Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Golestan, Iran.
authors.forename: Shahryar
authors.initials: S
authors.lastname: Semnani
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Roshandel
authors.forename: Azadehsadat
authors.initials: A
authors.lastname: Zendehbad
authors.forename: Abbasali
authors.initials: A
authors.lastname: Keshtkar
authors.forename: Hadi
authors.initials: H
authors.lastname: Rahimzadeh
authors.forename: Nafiseh
authors.initials: N
authors.lastname: Abdolahi
authors.forename: Sima
authors.initials: S
authors.lastname: Besharat
authors.forename: Abdolvahab
authors.initials: A
authors.lastname: Moradi
authors.forename: Honeyehsadat
authors.initials: H
authors.lastname: Mirkarimi
authors.forename: Seyedzinab
authors.initials: S
authors.lastname: Hasheminasab
mesh_terms: D055669:Ecological and Environmental Phenomena; D004938:Esophageal Neoplasms / Q000453:epidemiology*; D005843:Geography; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D012307:Risk Factors; D012643:Selenium / Q000032:analysis*; D012987:Soil / Q000032:analysis*
chemical_list: D012987:Soil; D012643:Selenium