title: [Comparative study on soil and vegetation characteristics from high- and low risk areas of esophageal cancer in China].
abstract: OBJECTIVE
  To study the types of soil and vegetation as well as soil organic carbon densities (SOCD) from high and low risk areas of esophageal cancer (EC) in China.
  
  
  METHODS
  Database from EC mortality survey in 1990-1992 in China was established in Excel. Digital polygon maps of study areas were created in ArcGIS 9.1 and linked with the database. The types of soil and vegetation from sampling areas were extracted from digital maps of soil type, vegetation type while the map of distribution on EC mortality was using the polygon overlay analysis. SOCD at depths of 100 cm and 20 cm of these areas were calculated, and spearman correlation analysis was used to evaluate the relationship between EC mortality and SOCD.
  
  
  RESULTS
  The types of soil and vegetation and related distributions from high and low risk areas of EC in China showed obvious differences. There were both negative correlations between EC mortality and SOCD at depths of 100 cm and 20 cm. The correlation coefficients for man were -0.504 and -0.575 (P = 0.004, 0.001 respectively), and that for woman were -0.487 and -0.526 (P = 0.003, 0.001 respectively).
  
  
  CONCLUSIONS
  Mortality rate of esophageal cancer might correlate to SOCD, the types of soil and vegetation which called for further studies.
authors.affiliation: Department of Preventive Medicine, Shantou University Medical College, Shantou 515031, China.
authors.forename: Ku-sheng
authors.initials: KS
authors.lastname: Wu
authors.forename: Xia
authors.initials: X
authors.lastname: Huo
mesh_terms: D002681:China / Q000453:epidemiology; D004784:Environmental Monitoring / Q000379:methods; D062665:Epidemiological Monitoring; D004938:Esophageal Neoplasms / Q000453:epidemiology*; D040362:Geographic Information Systems; D005843:Geography; D006801:Humans; D010944:Plants; D012987:Soil / Q000032:analysis*
chemical_list: D012987:Soil